Handbook for the Analysis and Identification of Alternative Refrigerants [1 ed.] 9781315893235, 9781351072335, 9781351089234, 9781351097680, 9781351080781

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Handbook for the Analysis and Identification of Alternative Refrigerants [1 ed.]
 9781315893235, 9781351072335, 9781351089234, 9781351097680, 9781351080781

Table of contents :

1. Chemical Analysis Methods for Alternative Refrigerants and Related Products 2. Analytical Data for Alternative Refrigerants and Related Materials

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Handbook for the ANALYSIS

and IDENTIFICATION of ALTERNATIVE REFRIGERANTS Thomas J. Bruno

Boca Raton London New York

CRC Press is an imprint of the Taylor & Francis Group, an informa business

CRC Press Boca Raton Ann Arbor London

Tokyo

First published 1995 by CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 Reissued 2018 by CRC Press © 1995 by CRC Press, Inc. CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use. The authors and publishers have attempted to trace the copyright holders of all material reproduced in this publication and apologize to copyright holders if permission to publish in this form has not been obtained. If any copyright material has not been acknowledged please write and let us know so we may rectify in any future reprint. Except as permitted under U.S. Copyright Law, no part of this book may be reprinted, reproduced, transmitted, or utilized in any form by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying, microfilming, and recording, or in any information storage or retrieval system, without written permission from the publishers. For permission to photocopy or use material electronically from this work, please access www.copyright.com (http://www.copyright. com/) or contact the Copyright Clearance Center, Inc. (CCC), 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400. CCC is a not-for-profit organization that provides licenses and registration for a variety of users. For organizations that have been granted a photocopy license by the CCC, a separate system of payment has been arranged. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. Library of Congress Cataloging-in-Publication Data Bruno, Thomas J.   Handbook for the analysis & identification of alternative refrigerants / by Thomas J. Bruno.   p. cm.   Includes bibliographical references and index.   ISBN 0-8493-3926-X   1.  Refrigerants.  I.  Title.  II.  Title: Handbook for the analysis and identification of alternative refrigerants.  TP492.7.B7 1995   621.5’64--dc20 

94-15443

A Library of Congress record exists under LC control number: 94015443 Publisher’s Note The publisher has gone to great lengths to ensure the quality of this reprint but points out that some imperfections in the original copies may be apparent. Disclaimer The publisher has made every effort to trace copyright holders and welcomes correspondence from those they have been unable to contact. ISBN 13: 978-1-315-89323-5 (hbk) ISBN 13: 978-1-351-07233-5 (ebk) Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com

To Kelly Anne

PREFACE Many laboratories are engaged in research on the development of new fluids for use as refrigerants, propellants, blowing agents, and foaming agents. These new materials are needed to replace the fully halogenated chemicals that are believed to contribute to atmospheric ozone depletion. This research involves the synthesis and detailed characterization of potential replacement fluids. An integral part of this effort is the chemical analysis of fluids that are prepared and tested. In this volume, we review the major chemical analysis methods that have been developed and used at NIST and elsewhere, and provide a compendium of analytical information that is of value for the design of chemical analyses. The first chapter provides a description of the major analytical methods applicable for alternative refrigerants and related products. This part is divided into three main sections: qualitative identification, quantitative determinations and separations, and reaction screening. The second chapter contains the analytical database, along with a detailed description of its use. Sources of safety information, a guide to the refrigerant numbering system, a useful computer program, a glossary, a unit conversion table, and a description of a critical parameter approximation method are provided in appendices. The Editor would like to acknowledge a number of individuals whose assistance has been critical in the preparation of this volume. A great debt is owed to the board of reviewers that was assembled to critically review the manuscript. This review board consisted of Drs. Marcia L. Huber, Richard F. Kayser, Anthony Lagalante, James E. Mayrath, Mark O. McClinden and Matt Young of NIST, Dr. Michele Leparulo-Loftus of Technical Assessment Systems, Inc., and Dr. Soraya Gayourmanesh of St. Johns University. Mr. Robert Einert (a chemical engineer at NIST), and Mr. Wesley Breshears (an engineering technician at NIST), provided valuable assistance in producing spectral graphics. The Editor would like to thank his secretary, Mrs. Cyndi Rule, who patiently worked through numerous revisions. The financial support of the Gas Research Institute (Chicago, IL) and the United States Department of Energy, Office of Building and Community Systems (Washington, D.C.) for some aspects of this work is gratefully acknowledged. Finally, the Editor would like to extend special thanks to his wife, Clare, for her extraordinary patience throughout the period of hard work and late nights.

THE AUTHOR Thomas J. Bruno, Ph.D., is currently Leader of the Process Separations Group at the National Institute of Standards and Technology (NIST), Boulder, Colorado, as well as an Adjunct Professor at the Colorado School of Mines, Golden, Colorado, Visiting Professor at Instituto Superior Technico, Lisbon, Portugal, and Chairman of the Board of Trustees of the Mamie Doud Eisenhower Library. He received his B.S. in chemistry from the Polytechnic Institute of Brooklyn, and his M.S. and Ph.D. in physical chemistry from Georgetown University. He served as a National Academy of Sciences-National Research Council postdoctoral associate at NIST, and was later appointed to the staff. Dr. Bruno has done research on properties of fuel mixtures, chemically reacting fluids, and environmental pollutants. He is also involved in research on supercritical fluid extraction and chromatography of bioproducts, the development of novel analytical methods for environmental contaminants and alternative refrigerants, and novel detection devices for chromatography. In his research areas, he has published approximately 80 papers, 5 books, and holds 12 patents. He was awarded the Department of Commerce Bronze Medal in 1986 for his work on the thermophysical properties of reacting fluids.

CONTRIBUTORS Thomas J. Bruno, Ph.D. Thermophysics Division Chemical Science and Technology Laboratory National Institute of Standards and Technology Boulder, Colorado 80303

Brian N. Hansen, Ph.D. Thermophysics Division Chemical Science and Technology Laboratory National Institute of Standards and Technology Boulder, Colorado 80303

Michael Caciari Thermophysics Division Chemical Science and Technology Laboratory National Institute of Standards and Technology Boulder, Colorado 80303 and Fort Lupton High School* Fort Lupton, Colorado 80621

Robert F.X. Klein, Ph.D. Department of Chemistry Georgetown University Washington, D.C. 20057 Paris D.N. Svoronos, Ph.D. Department of Chemistry Queensborough College of City University of New York Bayside, New York 11364

T. Christopher Waidner, Ph.D. Department of Chemistry Georgetown University Washington, D.C. 20057

* Permanent address.

CONTENTS 1. Chemical Analysis Methods for Alternative Refrigerants and Related Products Introduction Chemical Analysis Needs Qualitative Identification Mass Spectrometry Mass Spectral Interpretation Mass Spectral Fragmentation Patterns Mass Spectral Data Compendium Infrared Spectrophotometry Sampling Considerations for Infrared Spectrophotometry Interpretation of Infrared Spectra Ultraviolet-Visible Spectrophotometry Nuclear Magnetic Resonance Spectrometry 'H NMR Absorptions I3 C NMR Absorptions 19 FNMR Absorptions 17 O NMR Absorptions Spin-Spin Coupling Chromatographic Retention Parameters Adsorbent Tests Quantitation and Separation Methods Analysis of Organics Analysis of Air Headspace Analysis Analysis of Water Miscellaneous Analytical Methods Reaction Screening References

1 1 1 3 6 9 10 13 15 16 16 19 19 21 22 24 25 25 26 29 32 32 35 43 45 47 47 50

2. Analytical Data for Alternative Refrigerants and Related Materials Introduction Physical Properties Safety Information Analytical Data References List of Abbreviations and Symbols

57 57 57 59 61 63 64

11 12 13 14 21 22 23 32 40 41 112

fluorotrichloromethane dichlorodifluoromethane chlorotrifluoromethane tetrafluoromethane dichlorofluoromethane chlorodifluoromethane trifluoromethane difluoromethane chloromethane fluorome thane l,2-difluoro-l,l,2,2-tetrachloroethane

65 69 73 77 81 85 89 93 97 102 106

112a 113 113a 114 114a 115 116 121 122 123 123a 124 125 131 13 la 132b 133a 134 134a 141 141b 142b 143 143a 150 152 152a 160 161 113B2a(3 113B2 114B1 114B2 123B1 123B2 123aBla 132bB2 133aBl 142B1 151B1 160B1 1110 1111 1112 1112a 1113 1114 1120 1121

1,1-difluorotetrachloroethane 1,1,2-trichlorotrifluoroethane l,l,l-trichloro-2,2,2-trifluoroethane 1,2-dichlorotetrafluoroethane 1,1-dichlorotetrafluoroethane chloropentafluoroethane hexafluoroethane 1,1,2,2-tetrachlorofluoroethane l,l-difluoro-l,2,2-trichloroethane 2,2-dichloro-l,l,l-trifluoroethane l,2-dichloro-l,l,2-trifluoroethane 2-chloro-l,l,l,2-tetrafluoroethane pentafluoroethane l,l,2-trichloro-2-fluoroethane 1,1,2-trichloro-l-fluoroethane l,2-dichloro-l,l-difluoroethane 2-chloro-l,l,l-trifluoroethane 1,1,2,2-tetrafluoroethane 1,1,1,2-tetrafluoroethane 1,2-dichloro-l-fluoroethane 1,1-dichloro-l-fluoroethane l-chloro-l,l-difluoroethane 1,1,2-trifluoroethane 1,1,1-trifluoroethane 1,2-dichloroethane 1,2-difluoroethane 1,1-difluoroethane chloroethane fluoroethane 2-chloro-l,2-dibromo-l,l,2-trifluoroethane l-chloro-l,l-dibromotrifluoroethane l-bromo-2-chlorotetrafluoroethane 1,2-dibromotetrafluoroethane 2-bromo-2-chloro- 1,1,1-trifluoroethane l,2-dibromo-l,l,2-trifluoroethane 1 -bromo-2-chloro-1,1,2-trifluoroethane 1,2-dibromo-1,1-difluoroethane 2,2,2-trifluoroethyl bromide 2-bromo-1,1-difluoroethane l-bromo-2-fluoroethane bromoethane tetrachloroethylene trichlorofluoroethylene 1,2-dichloro-1,2-difluoroethylene l,l-dichloro-2,2-difluoroethylene chlorotrifluoroethylene tetrafluoroethylene 1,1,2-trichloroethylene 1,2-dichloro-l-fluoroethylene

111 116 121 127 132 137 142 146 152 158 164 169 175 181 188 193 198 203 209 213 219 224 230 236 241 245 250 256 261 267 272 277 281 286 292 297 305 311 316 322 329 333 337 342 347 352 357 361 366

1122 1123 1130 1130 1130a 113 la 1132a 1141 1112aB2 1113B1 1122B1 1140B1 215aa 215ba 216ba 217ba 225ca 225cb 227ea 236ea 243db 253fb 262da 263fb 270aa 270fa 270da 270fb 280da 280fa 216B2 217caBl 280Bla 280B1 1243b 1250 1250 1250a 1250b 1260 1260B1 2240 E134 E150a El60 E263 E270b E280 E280a

2-chloro-l,l-difluoroethylene 1,1,2-trifluoroethylene cis-l,2-dichloroethylene trans-1,2-dichloroethylene 1,1-dichloroethylene 1-chloro-l-fluoroethylene 1,1-difluoroethylene fluoroethylene 1,1-dibromodifluoroethylene bromotrifluoroethylene (property data only) l-bromo-2,2-difluoroethylene bromoethylene l,2,2-trichloro-l,l,3,3,3-pentafluoropropane 1,2,3-trichloropentafluoropropane 1,2-dichlorohexafluoropropane 2-chloroheptafluoropropane 3,3-dichloro-1,1,1,2,2-pentafluoropropane 1,3-dichloro-1,1,2,2,3-pentafluoropropane 1,1,1,2,3,3,3-heptafluoropropane 1,1,1,2,3,3-hexafluoropropane 2,3-dichloro-l,l,l-trifluoropropane 3-chloro-l,l,l-trifluoropropane 2-chloro-l,3-difluoropropane 1,1,1-trifluoropropane 2,2-dichloropropane 1,3-dichloropropane 1,2-dichloropropane 1,1-dichloropropane 2-chloropropane 1-chloropropane l,2-dibromo-l,l,2,3,3,3-hexafluoropropane n-heptafluoropropyl bromide 1-bromopropane 2-bromopropane 3,3,3-trifluoro-l-propene cis-l,3-dichloro-l-propene trans-1,3-dichloro-1-propene 2,3-dichloro-l -propene 1,1-dichloro-l -propene (property data only) 3-chloro-l-propene 3-bromo-1-propene 3-chloro-l-propyne bis(difluoromethyl) ether a,a-dichloromethyl methyl ether chloromethyl methyl ether 2-methoxy-l,l,l-trifluoroethane 2,2-dichloroethyl methyl ether 2-chloroethyl methyl ether chloromethyl ethyl ether

371 376 381 383 388 393 398 403 408 413 414 419 424 428 433 438 443 446 450 456 461 467 472 478 484 489 494 499 504 508 513 518 523 527 532 536 538 543 548 549 553 557 561 565 570 574 578 582 587

APPENDICES Appendix 1 Appendix 2 Appendix 3 Appendix 4 Appendix 5 Appendix 6

Sources of Toxicological Information and Properties Refrigerant Numbering System A Computer Program to Aid in the Interpretation of Mass Spectra of Alternative Refrigerants Glossary and Abbreviation List Unit Conversions Joback's Method for Critical Property Estimation

INDEXES Chemical Index Subject Index

593 595 597 631 637 645 647 651

Chapter 1

CHEMICAL ANALYSIS METHODS FOR ALTERNATIVE REFRIGERANTS AND RELATED PRODUCTS Thomas J. Bruno Thermophysics Division National Institute of Standards and Technology Boulder, CO 80303

INTRODUCTION The threat of atmospheric ozone depletion has led to a great deal of research in many laboratories worldwide to find suitable substitutes for most of the fully halogenated fluids. These fluids have been used for many years as refrigerants, blowing/foaming agents, and propellants. Since the production of many of these fluids is being phased out in many industrialized nations, there is a pressing need to thoroughly characterize the more promising substitutes [1]. These substitutes may be pure fluids or mixtures (usually binary or ternary) of pure fluids. The characterization of these fluids is a multifaceted problem that involves chemical and biological science as well as applied engineering design. The problem includes thermophysical property measurements and correlation [2], materials compatibility and stability studies, and toxicity studies, to name a few. For the design of efficient and predictable refrigerant cycles, the knowledge of important thermophysical properties is foremost. We will therefore focus our discussion and operational illustrations in this area, but we must not lose sight of the many other research and engineering tasks that must be completed before substitutes are in service. All of this work has a common requirement: the effective and efficient chemical analysis of the potential replacement fluids.

CHEMICAL ANALYSIS NEEDS The thermophysical properties that will be needed for effective design calculations include both equilibrium and transport properties. Some of the relevant equilibrium properties include the P-V-T surfaces, sound speeds, critical parameters, heat capacities, refractive indices [3-18], surface tensions [15], and dipole moments [19-21]. The important transport properties include thermal conductivity and viscosity [4,11]. It is of paramount importance that the experimental measurements of these properties be performed on materials of known composition. This means that the purity of each fluid studied must be an important consideration at an early stage of the experimental measurement of each property. This is a nontrivial problem, especially with newer materials, because it is often difficult or impossible to obtain some classes of fluids at the purity levels that are normally associated with "research grade" reagents and samples. Further purification can be quite difficult and labor intensive, and often requires large and costly distillation columns, zone refiners, or preparative-scale gas chromatographs. The experimental results of most measurements cannot be properly interpreted without a detailed knowledge of the sample constituents. Under some circumstances, for example, a nominally single-component fluid may have to be treated as a mixture in the mathematical analysis of the results if the level of impurities is high. Specific impurities that may be present in a sample may even make some measurements impossible or cause spurious results that may or may not go undetected. Water and air are two examples of contaminants that can plague an experimental measurement. Low levels of water 1

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CRC Handbook for the Identification and Analysis of Alternative Refrigerants

can cause plugging of small-diameter transfer lines that must be operated at lower temperatures. In addition, some measurements are seriously disturbed by the comparatively high electrical conductivity of water, e.g., viscosity measurements based upon a torsionally vibrating quartz crystal. Air dissolved in fluids may cause vapor locking that can prevent the filling of measurement cells in experimental apparatus. The presence of oils and lubricants in valves (of supply or sample cylinders) can also present a problem, since many of the alternative refrigerant fluids are moderately good solvents, especially in the supercritical fluid state. These heavy hydrocarbon impurities can be present in the cylinder or container obtained from the supplier, or introduced inadvertently in the laboratory. Dissolved heavy hydrocarbons can be an especially vexing problem, since many oils will be moderately soluble at higher pressures (and densities), but will precipitate out of solution at atmospheric pressure. This can make the detection of a heavy hydrocarbon contaminant very difficult, since the contaminant is usually left behind in a transfer line. Another aspect of the overall characterization problem is the effect of chemical decomposition and the reaction of the fluids with the materials of construction. These materials include metal parts such as heat exchangers, nozzles, and transfer lines, in addition to elastomeric seals. This consideration naturally applies to experimental apparatus used in the measurement of thermophysical properties, as discussed above. Moreover, it is very common for chemical degradation of the fluid to occur during the course of a measurement, especially under conditions of high temperature and pressure. Chemical stability considerations also very clearly pertain to the operation of fluids in a refrigeration cycle. Many of the alternative refrigerant fluids are very aggressive toward common metals as well as the more active metals. The reactions can be especially vigorous if the metals are finely divided. The chemical incompatibilities of all the fluids listed in Chapter 2 are addressed either by reference to experimental measurements or chemical predictions. Reactivity may be enhanced at elevated temperatures or in the presence of certain impurities. The chemical decomposition of these fluids can result in the formation of highly corrosive chemicals such as HP (hydrofluoric acid) and HC1 (hydrochloric acid), and highly toxic materials such as carbonyl halides, phosgene, and carbon monoxide. Prudence dictates that the potential for inadvertently synthesizing such products be addressed under controlled conditions well in advance of the actual property characterization measurement. The possible catalytic effects of the construction materials of experimental apparatus should also be studied. In this chapter, the general analytical protocol applied to alternative refrigerant fluids that are studied at the Thermophysics Division of the National Institute of Standards and Technology will be treated. The discussion will be divided into three main parts: qualitative identification, quantitative determinations (especially those involving separation methods), and reaction screening. The qualitative identification discussion will focus on the verification of sample identity and the characterization of the major impurities that may be present. This process includes the identification of both positional and geometric isomers [22,23]. Quantitation involves the optimization of analyses to provide the required level of accuracy in the determination of the concentrations of impurities [24,25]. This discussion will include some of the novel instrumental modifications that have been developed for these analyses. The discussion of reaction screening will center around a protocol and apparatus developed in recent years for the support of high-temperature, high-pressure property measurements. The analytical protocol in place at NIST is shown in flowchart form on Figure 1. There are three major steps in the process, the detailed applicability of which will be treated in the next paragraph. The first step is the chemical analysis of the starting materials, a process that often focuses on specific types of impurities, given prior chemical or historical knowledge about the fluid. Next, the desired properties are measured. Although at NIST these measurements are usually the determination of thermophysical properties, the process outlined in Figure 1 is

Chemical Analysis Methods for Alternative Refrigerants and Related Products

3

general in that any type of measurement may be substituted here. Finally, in step 3, the analysis and characterization of the final contents of measurement apparatus are performed. The strategy begins with the arrival (or synthesis) of the fluid and always starts with a study of the hazards of the material. The material safety data sheet (MSDS), several on-line databases, and published sources of information are consulted. The major sources are summarized in Appendix 1 and safety information is summarized for each of the fluids listed in Chapter 2. One must not confine this search to the MSDS alone, since these sources of information are notoriously unreliable. On the other hand, a comprehensive study helps to provide an environment in which the materials can be handled safely. This is clearly one of the most important steps in the analytical process. If very little is known about a given fluid, a high level of hazard must be assumed, and the material should be handled accordingly (glove-box operations, protective clothing, exclusion of light, and restricted laboratory access, for example). The next step is a battery of analytical tests applied to the sample(s) before any property characterization measurements are performed. The identity of the sample is verified, and the major impurities (including organics and inorganics) are determined. Since most refrigerant fluids are hygroscopic, water analysis — either using a chromatographic method or the Karl Fisher titration — is always performed. Adsorbent tests are performed to assess the presence of heavy contaminants. When measurements under relatively severe conditions of high temperature and pressure are anticipated, reaction screening should be part of the initial analytical step. The reaction screening process includes the study of possible catalytic effects due to the construction materials of the measurement apparatus. After the property measurements (or other tests) have been made, the sample is recovered (if possible), and an additional series of tests is performed. Sample recovery is usually accomplished by condensing the fluid in stainless steel pressure vessels that are cooled in liquid nitrogen or some other suitable low temperature bath. The possibility of chemical decomposition occurring during a measurement requires that each sample of fluid be recovered and checked for organics. To assess the possibility of a fluid being inadvertently contaminated in an apparatus, water analysis and adsorbent tests may also be repeated. In addition, it is sometimes necessary to recheck for air, since a leak in an apparatus may not be detected in any other way. A summary of results obtained from the analyses is always included in the report of any measured properties.

QUALITATIVE IDENTIFICATION The most useful instrumental techniques for the qualitative identification of alternative refrigerant components are mass spectrometry (MS), infrared absorption spectrophotometry (IR), nuclear magnetic resonance spectrometry (NMR of the 'H, I3 C, and 19F nuclei), and gas chromatography. In addition, ultraviolet-visible absorption spectrophotometry (UV-vis) is very often of value in distinguishing chlorinated, brominated, and unsaturated compounds. Whenever possible, it is highly desirable to have the results from more than one of these techniques available for study, especially in the more difficult or critical cases. Some of the techniques listed above must be augmented with additional information from other measurements, since they cannot themselves provide unequivocal identification. These methods include infrared spectrophotometry, ultraviolet spectrophotometry, and gas chromatography. These techniques are most useful in providing confirmatory information, and in cases where the analyst has a reasonably complete prior knowledge about the compound history and potential impurities. A collection of the mass, infrared, nuclear magnetic resonance, and UV-vis spectra, and the chromatographic retention behavior of many materials relevant to alternative refrigerant research is provided in Chapter 2 of this volume. An example of these collected data is

Figure 1.

A flow-chart presentation of the analytical protocol developed and employed at NIST for the characterization of alternative refrigerants and related products.

4 CRC Handbook for the Identification and Analysis of Alternative Refrigerants

Chemical Analysis Methods for Alternative Refrigerants and Related Products

R-141 b (a)

(b)

(c)

5

1,1-dichloro-1-fluoroethane

Mass Spectrum

13

(d)

C NMR

Infrared Spectrum

Ultraviolet Spectrum

(e)

19

(f)

1

FNMR

H NMR

Figure 2. An example of the kinds of analytical information contained in the compilation developed for alternative refrigerants and related products. For R-141b, 1,1-dichloro-l-fluoroethane, (a) mass spectrum, (b) infrared spectrum, (c) ultraviolet spectrum, (d-f) 13C, 19F, and 'H nuclear magnetic resonance spectra.

provided in Figure 2, containing the spectra for R-141b, l,l-dichloro-l-fluoroethane. In addition to these measurements, refractive indices (a very useful parameter for analytical identification), densities (or specific gravities), and other useful physical properties are provided, along with toxicity and safety information. Measurements performed on 110 chloro-, chlorofluoro-, hydrochlorofluoro-, and bromochlorofluoro-methanes, ethanes, ethylenes,

6

CRC Handbook for the Identification and Analysis of Alternative Refrigerants

propanes, propenes, and ethers have led to the development of this analytical data library [22,24J, as well as the recognition of some of the general analytical (spectral and chromatographic) characteristics of these molecules that are useful in the analysis of unknowns. These characteristics will be discussed in this chapter; the reader may turn to Chapter 2 to observe actual data. A listing of the materials included in this study is provided in Table 1. A discussion of the refrigerant code numbering system used in this table is provided in Appendix 2. In each case, the highest purity material commercially available was obtained for study. MASS SPECTROMETRY Mass spectrometry is perhaps the most useful and cost-effective (in terms of information content per unit cost) technique applicable to the analysis of alternative refrigerants and related products. A discussion of the elementary concepts of mass spectral instrumentation and experimental technique is beyond the scope of this review, and the reader is referred to several excellent sources for additional details [26-40]. Mass spectrometry is a technique having high sensitivity and specificity, and it can be coupled with other analytical methods such as gas and liquid chromatography and infrared spectrophotometry (so-called hyphenated techniques) [39,40]. Before we discuss the interpretation of the mass spectra of alternative refrigerants and their products, it will be of value to provide some basic definitions to prevent confusion with nomenclature. A mass spectrum is presented as a histogram of ion abundance (or intensity) on the "y" axis against the ratio of ion mass to charge (represented as m/e) on the "x" axis. Since most ions observed are of unit positive charge, we may consider the plot simply as the ion abundance versus the ion mass. Each peak on the spectrum represents a fragment of the original molecule. The largest peak on the spectrum, having the highest intensity (corresponding to the highest ion abundance) is called the base peak. Regardless of the intensity units employed for the "y" axis, all other peak intensities are expressed as a percent of the intensity of the base peak. The parent ion peak is produced by the fragment resulting from the loss of one electron from the molecule, and provides the relative molecular mass of the compound. It is usually represented as M, M+, or sometimes P+, and is the result of the least destructive collision of the original molecule with the ionization source. The ionization source may be a beam of electrons produced by a filament or an ion beam produced by a reagent gas. The parent ion peak is often called the molecular ion. In this chapter, we will designate the parent ion peak as M, and the parent ion as M+. The parent ion peak may also be the base peak, but this is not always the case. The major ion fragments (including the parent ion) occur within a spectral envelope called the isotopic cluster, a group of peaks that results from the natural atomic mass distribution of isotopes. A general halogen species will be represented as "X", and an alkyl species or an organic moiety will be represented as "R". When we refer to an immediate neighbor to a particular atom or functional group on a molecule, we will call this the a position or atom. Similarly, the next nearest atomic neighbor on a molecule will be the (3 position, and so on with y, 8, etc, referring to the positions that follow. It is often convenient to measure the mass spectrum of some alternative refrigerant fluids in a suitable solvent. Samples which are gaseous at room temperature can often be dissolved in carbon tetrachloride, toluene, or some other solvent, especially at temperatures near 0°C. In addition, some chlorofluorobromomethanes, -ethanes, -ethylenes, and haloethers are very sensitive to both air and moisture. Dissolving the sample in an anhydrous solvent provides a margin of safety and stability in the study of some of these compounds, and allows the use of many standard gas chromatography-mass spectrometry procedures. The important peaks in the mass spectra of most of the commonly used solvents are summarized in Table 2 [34]. This table may be used to distinguish the spectrum of the refrigerant from that of the solvent. As usual, a solvent blank should be measured to guard against the misinterpretation of impurity peaks present in the spectrum of the solvent itself.

Chemical Analysis Methods for Alternative Refrigerants and Related Products TABLE 1 List of Compounds Studied in the Development of Spectral Library and in the Study of Spectral Trends Codes* Methane Compounds

Ethane Compounds

Ethylene Compounds

11 12 13 14 21 22 23 32 40 41 112 1 12a 113 1 13a 114 1 14a 115 116 121 1 22 1 23 1 23a 1 24 1 25 131 1 31 a 1 32b 133a 134 134a 141 141b 142b 143 143a 150 152 152a 160 161 1 1 3B2a(3 1 1 3B2 1 1 4B 1 1 14B2 1 23B 1 1 23B2 1 23aB 1 a 1 32bB2 133aBl 142B1 1 51 B 1 1 60B 1 1110 1111 1112

Compounds fluorotrichloromethane dichlorodifluoromethane chlorotrifluoromethane tetrafluoromethane dichlorofluoromethane chlorodifluoromethane trifluoromethane difluoromethane chloromethane fluoromethane l,2-difluoro-l,l,2,2-tetrachloroethane 1 ,1-difluorotetrachloroethane 1,1 ,2-trichlorotrifluoroethane l,l,l-trichloro-2,2,2-trifluoroethane 1 ,2-dichlorotetrafluoroethane 1,1-dichlorotetrafluoroethane chloropentafluoroethane hexafluoroethane 1,1 ,2,2-tetrachlorofluoroethane 1,1 -difluoro- 1 ,2,2-trichloroethane 2,2-dichloro- 1,1,1 -trifluoroethane 1 ,2-dichloro- 1 , 1 ,2-trifluoroethane 2-chloro- 1,1,1 ,2-tetrafluoroethane pentafluoroethane 1,1 ,2-trichloro-2-fluoroethane 1,1 ,2-trichloro- 1 -fluoroethane 1 ,2-dichloro- 1 , 1 -difluoroethane 2,2,2-trifluoroethylchloride 1,1,2,2-tetrafluoroethane 1,1,1,2-tetrafluoroethane 1 ,2-dichlorofluoroethane 1,1-dichloro-l -fluoroethane 1-chloro- 1,1 -difluoroethane 1,1 ,2-trifluoroethane 1,1,1 -trifluoroethane 1,2-dichloroethane 1 ,2-difluoroethane 1,1 -difluoroethane chloroethane fluoroethane 2-chloro- 1 ,2-dibromo- 1 , 1 ,2-trifluoroethane 1 -chloro- 1 , 1 -dibromotrifluoroethane 1 -bromo-2-chlorotetrafluoroethane 1,2-dibromotetrafluoroethane 2-bromo-2-chloro- 1,1,1 -trifluoroethane 1 ,2-dibromo- 1 , 1 ,2-trifluoroethane 1 -bromo-2-chloro- 1 , 1 ,2-trifluoroethane 1 ,2-dibromo- 1 , 1 -difluoroethane 2,2,2-trifluoroethyl bromide 2-bromo- 1,1 -difluoroethane 1 -bromo-2-fluoroethane bromoethane tetrachloroethylene trichlorofluoroethylene 1 ,2-dichloro- 1 ,2-difluoroethylene

7

8

CRC Handbook for the Identification and Analysis of Alternative Refrigerants TABLE 1 (continued) List of Compounds Studied in the Development of Spectral Library and in the Study of Spectral Trends Codes*

Propane Compounds

Propene Compounds

Propyne Compounds Ether Compounds

1 1 1 2a 1113 1114 1 120 1121 1 1 22 1123 1130 1130a 113 la 1132a 1141 1 1 1 2aB2 1 1 1 3B 1 1 1 22B 1 1140B1 215aa 2 15ba 2 1 6ba 217ba 225ca 225cb 227ea 236ea 243db 262da 263fb 270aa 270fa 270da 270fb 280da 280fa 2 16B2 217caBl 280B 1 a 280B 1 1243b 1250 1250a 1250b 1260 1260B1 2240 El 34 E150a El 60 E263 E270b E280 E280a

Compounds 1,1 -dichloro-2,2-difluoroethylene chlorotrifluoroethylene tetrafluoroethy lene trichloroethylene 1 ,2-dichloro- 1 -fluoroethylene 2-chloro- 1 , 1 -difluoroethylene trifluoroethylene 1 ,2-dichloroethylene (cis- and trans-) 1,1-dichloroethylene 1-chloro-l -fluoroethylene 1,1 -difluoroethylene fluoroethylene 1 , 1 -dibromodifluoroethy lene bromotrifluoroethylene 1 -bromo-2,2-difluoroethy lene bromoethylene l,2,2-trichloro-l,l,3,3,3-pentafluoropropane 1 ,2,3-trichloropentafluoropropane 1 ,2-dichlorohexafluoropropane 2-chloroheptafluoropropane 3,3-dichloro- 1,1,1 ,2,2-pentafluoropropane 1 ,3-dichloro- 1 , 1 ,2,2,3-pentafluoropropane 1,1,1 ,2,3,3,3-heptafluoropropane 1,1,1 ,2,3,3-hexafluoropropane 2,3-dichloro- 1,1,1 -trifluoropropane 2-chloro- 1 ,3-difluoropropane 1,1,1 -trifluoropropane 2,2-dichloropropane 1,3-dichloropropane 1 ,2-dichloropropane 1 , 1 -dichloropropane 2-chloropropane 1-chloropropane 1 ,2-dibromo- 1 , 1 ,2,3,3,3-hexafluoropropane n-heptafluoropropyl bromide 1 -bromopropane 2-bromopropane 3,3,3-trifluoro-l-propene 1,3-dichloro-l-propene (cis- and trans-) 2,3-dichloro- 1-propene 1,1-dichloro- 1-propene 3-chloro- 1-propene 3-bromo-l-propene 3-chloro- 1-propyne bis(difluoromethyl) ether a,a-dichloromethyl methyl ether chloromethyl methyl ether 2-methoxy- 1,1,1 -trifluoroethane 2,2-dichloroethyl methyl ether 2-chloroethyl methyl ether chloromethyl ethyl ether

Codes are based on ANSI/ASHRAE 34-1992, Number Designation and Safety Classification of Refrigerants, American Society of Heating, Refrigerating and Air Conditioning Engineers, Atlanta, GA (USA), 1992.

Chemical Analysis Methods for Alternative Refrigerants and Related Products

9

TABLE 2 Important Peaks in the Mass Spectra of Common Solvents Solvents Water Methanol Acetonitrile Ethanol Dimethyl ether Acetone Acetic acid Ethylene glycol Furan Tetrahydrofuran n-Pentane Dimethylformamide (DMF) Diethylether Methyl acetate Carbon disulfide Benzene Pyridine Dichloromethane Cyclohexane n-Hexane p-Dioxane Tetramethylsilane (TMS) 1,2-Dimethoxy ethane Toluene Chloroform Chloroform-d, Carbon tetrachloride Tetrachloroethene

Formula

M

Important Peaks (m/e)

H,O CH,OH CH,CN CH,CH,OH CH,OCH, CH,COCH3 CH,CO2H HOCH,CH2OH C4H4O C4H8O C 5 H 12 HCON(CH,)2 (C2H5)2O CH,CO2CH, CS2 QH,, C5H5N CH,C1, C 6 H 12 C,,HI4 C4H8O2 (CH,)4Si (CH,OCH2)2 C6H,CH, CHC1, CDC1, CC14 CC12* CC12

18(100%) 32 41(100%) 46 46(100%) 58 60 62 68(100%) 72 72 73(100%) 74 74 76(100%) 78(100%) 79(100%) 84 84 86 88(100%) 88 90 92 118 119 152 (not seen) 164 (not seen)

17 31(100%),29,15 40,39,38,28,15 45,31(100%),27,15 45,29,15 43(100%),42,39,27,15 45,43,18,15 43,33,31(100%),29,18,15 42,39,38,37,29,18 71,43,42(100%),41,40,39,27, 18,157,18,15 57,43(100%),42,41,39,29,28,27,15 58,44,42,30,29,28,18,15 59,45,41,31(100%),29,27,15 59,43(100%),42,32,29,28,15 64,44,32 77,52,51,50,39,28 80,78,53,52,51,50,39,26 86,51,49(100%),48,47,35,28 69,56,55,43,42,41,39,27 85,71,69,57(100%),43,42,41,39,29,28,27 87,58,57,45,43,31,30,29,28 74,73,55,45,43,29 60,58,45(100%),31,29 91(100%),65,51,39,28 120,83,81(100%),47,35,28 121,84,82(100%),48,47,35,28 121,1 19,1 17(100%),84,82,58.5,47,35,28 168,166(100%),165,164,131, 128,129,95,94, 82,69,59,47,31,24

M = parent ion Taken from T.J. Bruno, P.D.N. Svoronos, CRC Handbook of Basic Tables for Chemical Analysis, CRC Press, Boca Raton, 1989.

Mass Spectral Interpretation The interpretation of a mass spectrum usually begins with the parent or molecular ion, if it is present in the spectrum. The occurrence of the parent ion peak on the spectrum is greatly dependent on the stability of this ion. In the case of HCFCs and HFCs, the parent ion is often present, but it may be weak in the case of many fluorides. The major exception is unsaturated aliphatic fluorides, in which one often observes the parent ion peak at a moderate intensity level. In the case of fully halogenated CFCs and haloethers, the appearance of a parent ion peak is much less likely. The common problem of low parent ion abundance in aliphatic halides having six or more carbons (for straight chains) and three or more carbons (for branched species) is usually not very serious in alternative refrigerant analysis, but must be borne in mind if polymerizations occur. The isotopic cluster of the parent ion of halocarbons is often rich with information, due to the natural isotopic abundances of each of the relevant isotopes. Table 3 shows the more important isotopes encountered in alternative refrigerant analysis, along with the percent abundance [34]. Chlorine and bromine are commonly called M + 2 elements (where M is the parent or molecular ion peak), because a relatively abundant heavier isotope is naturally present. This results in a peak multiplicity that is of significant help in spectrum interpretation.

10

CRC Handbook for the Identification and Analysis of Alternative Refrigerants TABLE 3 Natural Abundance of Relevant Isotopes Element

Total no. of isotopes

Hydrogen

3

Carbon

7

Fluorine Chlorine

6 11

Oxygen

8

Bromine

17

More prominent isotopes (mass, percent abundance) 'H(l. 00783, 99.985) H(2.01410, 0.015) 12 C(12.00000, 98.9) "C(l 3.00335, 1.1) "F( 18.99840, 100.0) "Cl(34.96885, 75.5) "Cl(36.96590, 24.5) I6 O( 15.99491, 99.8) IS O( 17.9992, 0.2) 7 "Br(78.9183, 50.5) RI Br(80.91642, 49.5) 2

Taken from T.J. Bruno, P.D.N. Svoronos, CRC Handbook of Basic Tables for Chemical Analysis, CRC Press, Boca Raton, 1989.

Table 4 presents calculated values of the relative abundances of the parent ion isotopic cluster for various combinations of chlorine and bromine (including species containing no bromine or no chlorine). The accuracy of the predictions is typically between 3 and 5 percent; the agreement of experimental data with the values in Table 4 greatly depends upon the instrument used to record the spectra. Aliphatic fluorides will produce characteristically small isotopic peaks with respect to the parent ion, a fact that can be of assistance in the identification process. Mass Spectral Fragmentation Patterns The fragmentation patterns observed from chlorofluorobromo methanes, -ethanes, -ethylenes, and -propanes are, in general, relatively simple. The halogen atoms usually have a relatively small influence on the mass spectral reactions. Complex rearrangement reactions are rarely seen, and the fragmentation is usually straightforward. The kind of fragmentation that will occur under electron impact conditions depends upon the relative bond strengths of the moieties that are summarized in Table 5 [34,41]. Some important bond strengths for polyatomic species are listed in Table 6 [37]. These data can be used to judge the relative importance of possible fragmentation mechanisms. The bonds between carbon and the heavier halogens (chlorine and bromine) are relatively weak, and fragmentation will be favored at these sites. The carbon-fluorine bond is considerably stronger than the others and, therefore, fragments of these bonds will be much less intense, if they are observed at all. These fragments will produce especially weak peaks if the molecule has one or more fluorines and one or more heavier halogens present on the carbon framework or backbone. The energy absorbed in the electron impact or chemical ionization process will be dissipated in the breaking of the weaker bonds rather than the C-F bond. In most cases of this simple cleavage, the hydrocarbon fragment will generally take the positive charge, and the halogen fragment will become the neutral radical species. The only common exception to this halocarbon fragmentation mechanism occurs with iodine-containing compounds. In these cases, the iodine usually retains the charge. The simple rearrangements producing HC1 and HF fragments can also occur, and these will be observed at M-36 and M-20. In the case of aliphatic bromides, the formation of HBr is not as likely as the loss of Br from the molecule. The occurrence of the reaction producing the HF species is more likely than those producing either HC1 or HBr, due to the more favorable

Chemical Analysis Methods for Alternative Refrigerants and Related Products

11

TABLE 4 Relative Intensities of Isotope Peaks for Combinations of Bromine and Chlorine C10

Cl,

CI2

Cl,

CI4

C15

C16

M+2 M+4 M+6 M+8 M+2 M+4 M+6 M+8 M + 10 M+2 M+4 M+6 M+8 M + 10 M + 12 M+2 M+4 M+6 M+8 M + 10 M + 12 M+2 M +4 M +6 M +8 M + 10 M + 12 M + 14 M+2 M+4 M+6 M+8 M + 10 M + 12 M + 14 M+2 M+4 M+6 M+8 M+10 M + 12

Br0

Br, 98.0

Br 2 196.0 96.1

Br, 294.0 288.2 94.1

32.5

130.6 31.9

228.0 159.0 31.2

326.1 383.1 187.4 30.7

65.0 10.6

163.0 74.4 10.4

261.1 234.2 83.3 10.2

359.3 490.2 312.8 91.7 9.8

97.5 31.7 3.4

195.3 127.0 34.4 3.3

294.0 99.7 159.4 37.1 3.2

130.0 63.3 13.7 1.2

228.3 190.9 75.8 14.4 1.1

326.6 414.9 263.1 88.8 15.4 1.3

393.3 609.8 473.8 193.9 39.6 3.0 4.2 735.3 670.0 347.1 102.2 16.2 0.7

162.6 105.7 34.3 5.5 0.3

260.7 265.3 137.9 39.3 5.8 0.3

358.9 520.8 397.9 174.5 44.3 5.7 0.5

Br4 390.8 547.7 375.3 92.0 424.6 704.2 564.1 214.8 30.3 456.3 840.3 791.6 397.5 99.2 10.1

195.3 158.6 68.8 16.6 2.1 0.1

M = Parent or molecular ion peak. Taken from T.J. Bruno, P.D.N. Svoronos, CRC Handbook of Basic Tables for Chemical Analysis, CRC Press, Boca Raton, 1989.

negative heat of formation of HF. The bond energy of the C-O ether linkage is very similar to that of the C-C bond, and one will often observe cleavage at the oxygen. There are only two main sources of CnH9nX+ ions that are observed in the mass spectra of alkyl halides. The first is cc-cleavage to form the R,C=X+ ion. This process results from the following trend, based on electron donating ability: F > Cl > Br > I, and produces unusually abundant (M - H)+ ions. The second is a displacement reaction that leads to unusually abundant C n H 2n X + ions

12

CRC Handbook for the Identification and Analysis of Alternative Refrigerants TABLE 5 Chemical Bond Energies of Relevance to Alternative Refrigerants Bond

Bond Energy kcal/g-bond

C-H C-C C=C C=C C-F C-C1 C-Br C-O

98.7 82.6 145.8 199.6 116 81 68 85.5

TABLE 6 Relevant Bond Strengths for Polyatomic Species Bond

Energy, kcal/mol

H-CH, H-CH,CH, CH,-CH, CH3-CH2CH, H - C=CH,

104 98 88 85 103

H CHy-C=CH,

92

H CH2=CH2 HC^CH H-CsCH H-CF, F-CH, Cl-CH,

163 230 125' 104 108 83.5

Bond

Energy, kcal/mol

Br-CH, F-CH2CH, C1-CH,CH, Br-CH,CH, Cl - C=CH,

70 106 81.5 69 84

H F-CF, Cl-CF, Br-CF, F-CC1, C1-CC1, Br-CCl, CH3-CF, CF3-CF3 CF2=CF,

129 85 70 106 73 54 100 97 76.3

' Approximation. Note; The table provides bond strengths for the bond indicated by the bold-faced symbols. These values are for a gas phase at 25°C and 1 atm pressure.

in compounds having more than four carbons. This mechanism is, therefore, of somewhat less importance for alternative refrigerant research. Fully halogenated compounds greatly resemble hydrocarbons in their mass spectral behavior, especially compounds having three or more carbons. Like aliphatic hydrocarbons, there is a high tendency to undergo rearrangement reactions. The smallest perhalogenated fragments are usually the most stable. The mass spectra of ethers, including halogenated ethers, will often show only very small parent ion peaks, and sometimes none at all. However, it is often possible to render the peak visible (along with the M + 1 peak) by introducing a larger sample into the mass spectrometer. This M + 1 peak is the result of H- transfer during an ion-molecule collision. lonization of an aliphatic ether usually begins with the loss of a nonbonding electron from the oxygen, followed by donation of the unpaired electron to the C-O bond. This is then followed by the transfer of an electron from another bond of this a-carbon (that is, (3- to the oxygen), which then cleaves to yield the alkyl radical (-R-) and the resonance stabilized oxonium ion. This is the familiar CH,=O+-R ion. The greater the double-bond character of this ion, the lower will

Chemical Analysis Methods for Alternative Refrigerants and Related Products

13

be the activation energy of this reaction and, therefore, the more intense will be the corresponding peak. Another important ether fragmentation mechanism is the cleavage of the C-O bond, which leaves the charge on the alkyl fragment. This produces the RO- and R + species, which one should look for on the spectrum. This is important because it can be used to determine the position of the oxygen in the case of unknown ethers. Other common fragments that should be considered are those resulting from the loss of CH2O and CHO. Mass Spectral Data Compendium By measuring the mass spectrum of each of the materials listed in Table 1, a compilation of the common fragments lost from typical alternative refrigerants and related products has been developed [22, 24]. The ion abundances have been normalized, and the expected peak intensity for each fragment has been calculated. These fragments, which are summarized in Table 7, are very useful in the analysis of an unknown spectrum. For the sake of completeness, this table includes a number of ions taken from the literature, in addition to those measured and provided in Part 2 of this volume [33]. These particular fragments are indicated with a dagger, "f". The mass/charge values provided are for low-resolution conditions. Users having access to high-resolution mass spectrometers can make adjustments in these values with the aid of Table 3. Fragments containing one or more bromine atoms are tabulated with the slightly more abundant 79Br isotope only. The reader should expect to find the corresponding signal due to 81Br in addition to that from the 79Br. The expected intensity of each fragment peak is rated from "strong" to "weak." When a range of intensity is expected, an asterisk (*) often denotes the most commonly observed intensity. In addition to the fragments listed in Table 7, there are several published correlations that can be very helpful [33]. The actual instrumental conditions used to measure an individual mass spectrum have a significant influence on the absolute ion abundances that will be measured. For this reason, a more quantitative prediction is not warranted in a compilation of this kind. In addition to instrumental factors, one must also consider the influence of the "departing species" that leads to the formation of a fragment. As an example, we can consider the fragment at a mass/charge = 63, identified in Table 7 as possibly CH2CH2C1, having an intensity ranging from medium to strong. The intensity will be stronger if the fragment results from the loss of a bromine atom, but much less intense if a fluorine atom must be lost to form the fragment. The mass/charge values listed in the table are those determined from the most abundant isotopes of the atoms constituting the fragment. Other relevant isotopic peaks will also be present in the mass spectrum and are an aid in identification using Tables 3 and 4 [34]. Thus, for the ion listed above at mass/charge = 63, one could expect to find an additional peak at 65, having an intensity approximately one third of that at 63. The user should always look for the presence of confirmatory peaks on a mass spectrum, especially when two or more fragments are known to give peaks at a given mass/charge value. As an example, at a mass/charge value of 117, two possible fragments are (1) CF2CFC1H and (2) CF_,CHC1. If, in addition, a strong peak is found at mass/charge = 69 (indicative of the CF, fragment), one can be more confident that the peak at 117 is due to fragment 2. This particular ion fragment serves a further purpose in that it corresponds to the main mass spectral peak observed for carbon tetrachloride. Therefore, it is important to verify the source of the fragment if the spectrum was recorded from a sample in solution. One should also look for the appearance of the "departing species" (the moiety that must be lost to form a particular fragment) elsewhere in the mass spectrum when deciding on the assignment of a particular peak. For example, if a -CF3 moiety must be lost to account for a peak, another peak at mass/charge = 69 should be present. Another factor that should be borne in mind when interpreting a mass spectrum is that not all mass spectral peaks have equal information content. In general, the relative information value of a peak increases with both the relative ion mass and the ion abundance. The most

14

CRC Handbook far (he Identification and Analysis of Alternative Refrigerants TABLE 7 Common Refrigerant Molecule Fragments

Mass/Charge

Fragment

Intensity

Mass/Charge

Fragment

19 27 29 31

F HC=CH, CHO CH,O CF1 CH2F Cl HC1 CH 2 =CHCH 2 CH,=CHCH, FC=CH, HC=CHF CHjOCH, C,H2Ff HC=CHF CH,CFf FCH2CH2 CH3CHF COF CHC1 CH2C1 CF, CHF2 CHjCHoOCHj HC^CCl HC=CHC1 C1C=CH2 CH2CHC1* CH,CH2C1 F 2 C=CH CH,CHC1 HFC=CF COCr FHC=CHF F 2 C=CH 2 CH2CHF2 CH,CF2 CH,FCHF FCC1 CFC1H CF, CHC1=CHCH2 CH2=CHCHC1 CH2=CC1CH, C,H5CI C,H6C1 CH2C1CH2CH, C1C=CF CH2FCH=CHF CH2CH2=CF2 79 Br FC=CHC1 HC=CFC1 C1C=CHF C1CH2OCH,

medium medium medium weak-strong variable medium strong medium*-strong strong strong strong strong strong variable variable variable strong strong strong weak medium weak*-medium strong strong medium strong strong variable medium-strong medium medium medium variable weak*-medium weak*-medium medium medium-strong medium medium weak-strong medium-strong* strong variable variable variable variable medium weak*-medium strong weak-medium medium-strong medium medium medium weak

80 81

HBr CH,CC1F CH,C1CFH C1CHCH2F F,C=CF 8l Br CH,OCHF2H F,C=CHF CC12 CF2HCF CH,CF, CHF2CHF CHC1, CF,CH2F CC1F2 CH,Br C1C=CC1 CH=CC12 C1C=CHC1 CH,=CCF, CH2C1CHC1 C1FC=CF CHC12CH2 CH,CC12 F,C=CHC1 FHC=CFC1 CH2C1CF2 CF2HCHC1 CH2FCFC1 CHFC1CHF CF,C1CH2 F2C=CF2 CC12F CF2HCF2 CF,CHF CH,C1CH2CHC1 CH,CC1,CH, CHC12CH,CH2 C1C=CCIF C1,C=CF CH2FCHC1CHF CF3CH2OCH2 CH2C1CFC1 CHC12CFH CH2FCC12 CC1,FCH, CHFCICHC1 CC1, CF,C1CHF CF2CFCIH CF,CHC1 CF2HCFC1 CHF,OCF2 CF.OCHF CF,CF,

33 35 36 41 42 45

47

48 49 50 51 59 60 61 62 63

64 65

66 67 69 75

76 77 78

79

82

83

85 93 94 95

97

98 99

100 101

111

113

115

117

119

Intensity weak*-medium strong medium-strong medium-strong medium medium strong weak-medium weak*-medium strong strong strong strong strong strong weak weak*-medium medium*-strong medium*-strong medium weak weak-medium weak-medium weak-medium weak-medium weak-medium weak-strong weak-strong weak-strong weak-strong weak-strong weak-medium strong weak weak-medium weak weak weak weak*-medium weak weak weak weak weak weak weak weak medium-strong medium medium strong medium weak weak medium

Chemical Analysis Methods for Alternative Refrigerants and Related Products

15

TABLE 7 (continued) Common Refrigerant Molecule Fragments Mass/Charge

Fragment

123

HBrC=CF FBrC=CH HFC=CBr CHFCH,Br CH2CHFBr CHBrCH,F CBrFCH, CF,Br C12C=CC1 CF3(C1)C=CH CF,(H)C=CC1 CF,H(C1)C=CF CF,C1(H)C=CF HCC12CHC1 CC13CH, CH2C1CC1, CF,CHC1, CF,C1CC1H CCI,CHF, CHFCFCU CF,CFHCFH CC1FCF, CF,CF,C1 BrC=CF, FC=CFBr

125

129

131

133

135 141 1

*

Intensity weak weak weak weak weak weak weak weak—medium medium strong weak—medium weak—medium weak—medium weak weak weak medium medium medium medium weak-medium strong medium weak weak

Mass/Charge

Fragment

143

CF,CH2Br CFBrCH2F CClFBr CCUFCF, CFC1CF,C1 CC1,CF, CFjCFHCF, CF,CFBrH CHFCBrF, CFBrCHF, CF,CICC1, CC13CF, CF,CF2CF2 CF,CBrClH BrF2CCF2 CF,CFBr CF,CC1FCF, CBrClCF, CF2CFBrCl CFClCF,Br CFBrCF,Cl CF,C1CC1FCF2 CClBr, CF,CFBrCF,

145 151

161

167 169 177 179 185 195

201 205 229

.

Intensity weak-medium weak-medium medium medium medium medium weak-medium strong strong strong weak—medium weak—medium strong weak-medium strong strong medium strong strong medium medium medium weak strong

Indicates a fragment taken from Reference 33. Indicates the more commonly observed intensity.

information-rich peaks, therefore, are those that are (1) at a relatively high ion mass and, (2) relatively abundant. It is more important and useful to have a thorough assignment of the heavier peaks on a mass spectrum rather than concentrating inordinately on the lighter fragments. A computer program that assists the user in the interpretation of the mass spectrum of an unknown has been developed, and it is designed to be especially useful for chlorofluorobromoethanes and -ethylenes. A listing of this program is provided in Appendix 3. The program provides possible combinations of atoms which can form a given mass/charge value for a fragment. A search of common refrigerant fragments and an analysis of the molecular ion cluster are also included. The program is written in Turbo Pascal (5.0), and requires at least 256k bytes of memory to run on a personal computer. INFRARED SPECTROPHOTOMETRY Infrared spectrophotometry (IR) probes the interaction of a molecule with electromagnetic radiation that lies between the visible and microwave regions. This region of electromagnetic radiation is further subdivided. The mid-IR region (most useful for organic compounds) ranges from 4000 to 666 cirr1, or 2.5 to 15 j^m. The near-IR region (commonly abbreviated as NIR) ranges from 14,290 to 4000 cm-', or 0.7 to 2.5 ^m. The far-IR region ranges from 700 to 200 cm-', or 14.3 to 50 jam. A molecule responds to IR radiation when an absorption results in a change in the permanent dipole moment of a group on the molecule, and IR spectrophotometry is the study and interpretation of the absorption signals resulting from these changes or transitions [42-46].

16

CRC Handbook for the Identification and Analysis of Alternative Refrigerants

Sampling Considerations for Infrared Spectrophotometry We did not discuss the basic instrumental aspects of mass spectrometry, since many of the standard techniques can be used for the analysis of alternative refrigerants and their common products. It is important, however, in the case of IR to briefly treat one aspect of the measurement that can be a source of difficulty. Many of the fluids of interest are of intermediate volatility. They have a relatively high vapor pressure at ambient temperature but are not always conveniently handled as gases. For this reason, sample handling during the measurement of an infrared spectrum can pose problems. Fluids that are gaseous at room temperature can be measured in a gas cell of the type shown in Figure 3a, while those that are liquid can be measured in one such as in Figure 3b. For fluids of intermediate volatility, the cell shown in Figure 3c is helpful [47,48]. This cell chills the sample with cold air that is produced from a vortex tube [49-511, and allows the spectrum to be recorded while the sample is in the liquid state. The cold air not only chills the periphery of the salt plates, but also sweeps the primary (or entry) plate with cold air. This helps to prevent evaporation of the sample in the cell and the resultant bubbles that will cause spiking in the peaks of the spectrum. All three types of cells were used to generate the spectra presented in Chapter 2. Interpretation of Infrared Spectra Infrared spectrophotometry can often be very useful in the qualitative identification of refrigerants and refrigerant impurities [23,24]. It is also possible, of course, to use the BeerLambert law with infrared absorption or transmission measurements to obtain quantitative data having an accuracy of between 3 and 5 percent [42-46]. In this section, the discussion will focus on several useful spectral regions that provide information on the structure (and therefore the identity) of the refrigerant fluid or product. The first spectral section to note in the mid-infrared region is the C-H stretching (symmetric and asymmetric) band that occurs between 2850 and 3050 cnrr1. If absorptions occur in this region, they are usually very intense due to the large change in dipole moment that results during the C-H vibration. The presence of these bands in a spectrum is, of course, clear evidence of a refrigerant that is not fully halogenated. Conversely, the absence of bands centered around 3000 cirr1 is evidence of a fully halogenated refrigerant. If the carbon of the C-H band also carries a chlorine atom, the absorption is often shifted to a higher energy, usually centered at 3050 cnr1 and sometimes extending as far as 3100 cirr1. This effect sometimes occurs when the carbon carries a fluorine or bromine atom as well, but the assignment of the band in these cases is less reliable. A single hydrogen on a carbon that bears a fluorine absorbs at very close to 3000 cnr1, with an increase of 8 and 62 cnr1 for the incremental addition of one and two fluorine atoms. In this respect, the C-H region of the infrared spectra of refrigerants can sometimes resemble those of aromatic hydrocarbons. When a C-H band is observed, the multiplicity of the envelope is also worthy of note. When the band is due to a carbon that carries a single hydrogen, the absorption will be a single peak which is usually sharp. When the band is from a carbon having two hydrogens, it almost always occurs as a sharp doublet. When, in addition, the carbon also carries a chlorine or bromine, one of the peaks of the doublet will usually be shifted to a higher energy (above 3000 cm"1). For alkenes, the C-H vibrations will usually occur between 3200 and 3000 cm-'. The double-bond region of the infrared spectrum occurs between 1800 and 1500 cm"1. In this range, a medium to strong absorption centered at 1650 cm"1 is evidence of an ethylene(or propylene-) based compound, rather than an ethane- (or propane-) based compound. The intensity and shape of this band provides an indication of the degree of symmetry of the molecule. Since the change in dipole moment of the >C=C< stretching motion depends largely on the substituents, a relatively strong, broad absorption indicates that the distribution of atoms is highly asymmetric about the double bond. On the other hand, a weaker, thinner peak indicates a more nearly symmetric distribution on the molecule. Naturally, a molecule

Chemical Analysis Methods for Alternative Refrigerants and Related Products

17

a

b

c Figure 3. A schematic diagram illustrating three types of sample cells for obtaining an infrared spectrum: (a) a cell for gaseous samples, (b) a cell for liquids, and (c) a chilled cell for compounds of intermediate vapor pressures.

with mirror plane symmetry with respect to the double bond will have no change in dipole moment due to the >C=C< symmetric vibration. These vibrations will be inactive in the infrared (the transitions being forbidden by quantum mechanical considerations) and will produce no absorptions or absorptions which are very weak. The >C=C< stretching frequency is unusually high when the carbon(s) also carry two or more fluorines. As an example, the double bond of the >C=CF2 group absorbs at 1755 to 1735 cm-', and that of -CF=CF2

18

CRC Handbook for the Identification and Analysis of Alternative Refrigerants TABLE 8 Infrared Absorptions of Carbon-Halogen Bonds 1

General formula

>C-X stretch

>CX, stretch

-CX, stretch

>C-X stretch

X=F

1120-1010

1350-1200 (asym) 1230-1100 (sym)

1230-1100

X=C1

830-500

1350-1200 (asym) 1200-1080 (sym) 845-795 (asym)

1510-1480 (overtone) X=Br

-620 (sym)

667-290

Taken from T.J. Bruno, P.D.N. Svoronos, CRC Handbook of Basic Tables for Chemical Analysis, CRC Press, Boca Raton, 1989.

absorbs at 1800 to 1780 crrr1. Note that the considerations of centrosymmetry apply here as well, however. Thus, the absorption due to >C=C< stretching for trans-1,2-difluoroethylene will hardly be detected. The characteristic absorptions from carbon-halogen bonds are summarized in Table 8 [34], The C-C1 absorptions are found in the range of 830 to 500 cnr'. When more than one chlorine atom is bonded to the carbon, the observed band is more intense and is located at the higher frequency end of these stated limits. Brominated compounds absorb in the 667 to 290 cnr1 range, while fluorinated compounds absorb strongly in the 1120 to 1010 cnr1 range. These absorptions occur in what is commonly referred to as the fingerprint region, since many absorptions which are found between 1500 and 600 cnr1 are characteristic of strongly correlated whole-molecule vibrations. Since most single bonds absorb at similar frequencies, the vibrations tend to couple and thus reflect the characteristics of the entire molecule. These numerous vibrations almost always complicate this spectral region, and make the carbonhalogen peaks difficult to interpret. Furthermore, the absorptions due to C-Br stretching often lie outside the range of many mid-infrared spectrophotometers. The C-F vibrations produce a useful overtone envelope between 1900 and 2600 cnr1. The number of peaks and the complexity of the envelope increase as the number of fluorine atoms on the molecule increases. The infrared spectra of ethers is the result of the asymmetric stretching vibration of the C-O-C system. The vibrational characteristics are similar to those of the skeletal .. .-C-C-C—... system, and the absorption is found in the same spectral region. The much larger change in dipole moment associated with the ether linkage asymmetric stretching vibration makes this band far more intense than that produced by the carbon chain. Thus, for aliphatic ethers, the most characteristic absorption is in the 1150 to 1085 cnr1 region, but is most often centered near 1125 cnr1. Note that this interferes with the absorptions of many C-X vibrations. The IR absorptions of ethers are summarized in Table 9, and the presence of halogen atoms on the carbons a to the ether linkage appears to have little effect on the absorption wavelength. The special case of vinyl ethers is worthy of mention. The asymmetric C-O-C stretch of alkyl vinyl ethers (the general CH,=CH-O-C4— family) produces a strong absorption at 1225 to 1200 cm^1. The ether linkage will also alter the absorption of the >C=C< stretching vibration of the vinyl group. This absorption becomes far more intense and appears as a doublet. One band is found near 1640 cnr1, and a slightly stronger one is found at 1620 cnr1. The intensities of these bands are temperature dependent.

Chemical Analysis Methods for Alternative Refrigerants and Related Products

19

TABLE 9 Infrared Absorptions of Ethers Ethers

Wave numbers (cm-1) >C-O-C< stretch asymmetrical

R'-Q-R2 Aliphatic (R',R'=alkyl)

Vinyl R'=vinyl R 2 =aryl

1 150-1085(s) Branching off on the carbons adjacent to oxygen creates splitting 1225-1200(s) (high due to resonance)

>C-O-C< stretch symmetrical

Very hard to trace

1075-1020(s)

1660-1610(m) (>C=CC=C - H) (wagging)

Taken from T.J. Bruno, P.D.N. Svoronos, CRC Handbook of Basic Tables for Chemical Analysis. CRC Press, Boca Raton, 1989.

The region between 3700 and 3200 cnr1 contains absorptions due to water contamination. Very high levels of water (0.5 percent by mass or higher) will produce the familiar broad band of medium intensity, while lower levels (down to the detectable limit of about 0.1 percent) produce a thinner, less intense peak shifted to slightly higher energy (and wave number). ULTRAVIOLET-VISIBLE SPECTROPHOTOMETRY Ultraviolet-visible (UV-vis) spectrophotometry probes the interaction of electromagnetic radiation (in the wavelength range of 190 to 850 nm) with matter, producing changes in the electronic energy levels of molecules [52,53]. Chemical moieties that absorb in this region are called chromophores. Most aspects of the instrumentation and technique are straightforward and will not be discussed here. As in the case of IR spectrophotometry, the only possible exception is in sample handling. A high-pressure cell is often required to obtain UV-vis spectra of the more volatile fluids. Such a cell is presented in Figure 4 [54]. This cell, with its associated instrumentation, permits control of sample pressure and temperature. This device was used to generate the UV-vis spectra presented in Chapter 2. UV-vis spectrophotometry is admittedly of limited utility in the analysis of alternative refrigerant fluids and products, but several features of the spectra are helpful and worthwhile. The UV-vis spectra of saturated haloalkanes are unremarkable, having absorptions in the higher energy range of the UV region (approximately 190 nm) corresponding to the n-a* transition. This is the transition of an electron from a nonbonding orbital to an antibonding sigma orbital. The presence of chlorine or bromine on the molecule shifts these absorptions to the 220 to 240 nm range. These heavier halogen species act as auxochromes or auxiliary chromophores. The presence of a double bond results in an absorption frequency at 200 to 220 nm. The incremental addition of fluorine to the unsaturated system has little effect on the absorption. The incremental addition of chlorine or bromine has a very large effect, resulting in a shift of the absorption to the range between 230 and 280 nm. NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY Nuclear magnetic resonance spectrometry (NMR) was once the private preserve of the organic chemist interested in structural determination. In this context, structural determination refers to the arrangements of atoms and bonds on a molecule rather than, for example, the macroscopic crystal structure of a solid. The development of high resolution NMR spectroscopy

20

CRC Handbook for the Identification and Analysis of Alternative Refrigerants

and very sensitive pulse techniques during the period of 1960-1980 has made the method very valuable to the analytical chemist. As an analytical technique to apply to the study of alternative refrigerants and products, it is one of the most expensive and complex, however. We include it here because it can often answer questions not easily approached by the other techniques. For many of the compounds treated in Chapter 2, NMR spectra are provided to assist in identification. NMR spectroscopy is a complex topic that cannot be treated adequately in a short discussion. There are many excellent texts that provide a clear and detailed discussion [55-66], so we will limit ourselves to a brief overview. The nuclei of certain elements possess both a spin angular momentum and an associated magnetic moment. These are the elements that have a spin quantum number, I, greater than 0. For our purposes, the most important of these nuclei are the proton, 'H, 13C, and I9F, all of which have spin quantum numbers of 1/2. In the cases of 'H and 19F, the natural abundances of the isotopes are high (99.985 and 100 percents, respectively), so instrumental sensitivity is high. In the case of I3C, the natural abundance is only 1.108 percent, so the instrumental sensitivity is much lower. Nuclei that have spin quantum numbers in excess of 1/2 also possess a quadrupole moment which causes severe broadening of the NMR absorptions. This aspect will be important later in the discussion of 17 O NMR. When these nuclei (I > 0) are placed in an external magnetic field, they can adopt one of a number of quantum-mechanically allowed orientations. Each of these orientations corresponds to a particular energy level, similar to the vibrational energy levels probed by IR spectrophotometry and the electronic energy levels probed by UV-vis spectrophotometry. NMR spectroscopy consists of observing the transitions between these levels, an occurrence that may be induced by the absorption of radio frequency (if) radiation perpendicular to the applied magnetic field. The exact frequency of the rf field that is required to cause the transition corresponds to the (quantized) difference in energy between the spin states. When the nucleus absorbs the rf field of appropriate energy (and therefore frequency), and the transition occurs, a condition of resonance is said to exist between the nucleus and the applied rf field. The frequency at which a particular nucleus comes to the resonance condition is dependent upon three basic factors. The first factor is the applied magnetic field strength. As the field strength increases, the energy difference between the spin states increases as well. The second factor is a characteristic of the nucleus itself, called the gyromagnetic ratio (sometimes called the magnetogyric ratio). This is the ratio of the magnetic moment to the angular momentum and is different for each nucleus. The third factor is the molecular environment of the nucleus. This last parameter is what makes NMR spectroscopy so important for the identification of molecules and the assignment of structure. Were it not for the effect of molecular environment, all NMR resonances would occur at the same frequency in a given magnetic field. It is the different chemical (and therefore magnetic) environments, caused by differences in nuclear shielding by the electrons, that provide the frequency dispersion that is recorded as an NMR spectrum. The departure or change in resonance frequency caused by the molecular environment is called the chemical shift. It is usually expressed in terms of a displacement of parts per million (ppm) in frequency from a carefully chosen standard. For 'H and I3C, the standard is usually tetramethylsilane (TMS, (CH3)4Si), while for 19F, the standard is usually trichlorofluoromethane (TFM, CC13F). The use of this unit of measure makes the chemical shift independent of both the applied field strength and the rf field frequency. The strict definition of chemical shift, CS, is, therefore:

Chemical Analysis Methods for Alternative Refrigerants and Related Products

21

Figure 4A. A schematic diagram of a high-pressure cell used to obtain ultraviolet-visible spectra of fluids, showing (a) pressure transducer, (b) O-ring seal, (c) spacer cartridge, (d) high-pressure inlet/outlet fitting, (e) window holder, (f) PTFE gasket, (g) quartz window, (g) magnetic stirrer bar, (h) NbFeB permanent magnet, and (i) stirrer motor.

where vs is the frequency of absorption of the sample and vr is that of the reference compound. It should be noted that the usual symbol for the chemical shift is 8. We have chosen to use CS to avoid confusion with the reference to the fourth nearest atomic neighbor on a molecule, the 5-species or group. J

H NMR Absorptions The absorptions in 'H NMR typically cover a range of only 10 ppm from TMS, while those of I3C and I9F are 250 and 800 ppm, respectively. This greater CS range, along with a high magnetic sensitivity to subtle structural changes, provides a high degree of resolution (between chemical species) and a highly valuable spectral information content. The expected proton chemical shifts of compounds of interest in alternative refrigerant analysis can be predicted with the Shoolery (for substituted methanes) and Strehlow (for carbon chains above methane) correlations. These additivity rules are summarized in Table 10. For substituted methanes, we use the group contributions and equation suggested by Shoolery [57]:

where CS is the predicted chemical shift. As an example, the proton resonances in methyl chloride and dichloromethane are predicted to be 2.76 and 5.29 ppm. No contribution factors

22

CRC Handbook for the Identification and Analysis of Alternative Refrigerants

Figure 4B. The same cell depicted in Figure 4A, but rotated 90°, showing (a) high-pressure inlet/outlet fitting, (b) heater, (c) window holder, (d) quartz window, and (e) platinum resistance thermometer.

have been determined for fluorine substituents on methane, at least partly due to the rather low solubility of these materials in common solvents and the difficulty that this causes in terms of dilute samples. For larger structures, the correlation equation of Strehlow [57] is of value:

The carbon skeleton is numbered starting with the a-carbon to the proton of interest. The S; values for the p-carbons are provided in Table 10, along with the group contributions for substituents. For the interpretation of 'H NMR spectra of ethers, the information in Table 11 provides additional guidance [67]. Note that the data shown are not for halogenated ethers. As a rough guide, one must add to the values in Table 11 an increment of 2 ppm for the addition of the first fluorine to the molecule and 1.5 ppm for the addition of a second. In the case of chlorine, one adds 1.8 ppm for the first, and 1.4 for the second. "C NMR Absorptions Since the development of sensitive pulse NMR spectrometers, high-speed computers, and fast-Fourier transform techniques, the study of I3C NMR spectra as an analytical tool has been possible. The larger effective CS range provides far greater resolution than 'H NMR. Because of the spin quantum number of 1/2 for 13C, the absorptions are sharp, as in the case of 'H. 13C

Chemical Analysis Methods for Alternative Refrigerants and Related Products

23

TABLE 10 'H Chemical Shifts for Alternative Refrigerant Product Analysis The chemical shift of a particular 'H can be approximated by a group contribution method. Substituted Methanes (Shoolery's correlation): 08 = 0.23 + ^8,

substituent -Cl -Br -I -OR -CF,

Sf

2.53 2.33 1.82 2.36 1.14

Higher Skeletal Increments (Strehlow's correlation): 08 = 0.933 + ^8; structure/substituent

Si; B-carbon 0.248 0.244

0.147

-F (position 2) -F (position 3) -Cl (position 1) -Cl (position 2) -Cl (position 3) -Br (position 1) -Br (position 2) -Br (position 3)

0.089 0.131 2.170 0.254 0.177 1.995 0.363 0.023

NMR provides direct information about the carbon skeleton of the molecule. It is especially useful on fully halogenated compounds, where the 'H NMR spectrum will provide only indirect negative evidence about the identity of the compound. The same consideration applies for compounds with multiple chemically and magnetically equivalent hydrogens that absorb at the same or nearly the same frequency. Since molecules generally have more hydrogen atoms than carbon atoms, the I3C NMR spectra are generally simpler than the 'H spectra of the same compound. In addition, the spectra are not complicated by homonuclear ( I3 C- 13 C) spin-spin coupling to the same extent that 'H and 19F are. This is because of the lower isotopic abundance of "C; it is simply not as statistically likely that two adjoining carbon atoms on a molecule be of atomic number 13. Note that this is actually a double-edged sword, because much useful information is to be found in spin-spin coupling patterns (discussed later in this chapter), and these are absent in 13C NMR spectra. The correlation of I3C chemical shifts provides assistance in compound identification and structural elucidation. As with the proton chemical shifts, those for 13C are presented in terms of a group contribution approach. Following the correlation of Brown for alkanes and substituted alkanes: CS = 2.3 + 2S,

24

CRC Handbook for the Identification and Analysis of Alternative Refrigerants TABLE 11 Proton NMR Absorptions for Ethers, Relative to Tetramethylsilane Functionality CH,-O-R RCH2-O-R R:CH-O-R CH,C-O-R RCH2C-0-R R,CH-C-O-R R = alkyl group

Chemical Shift, ppm 3.2 3.4 3.6 1.2 1.5 1.8

For fluorinated ethers: add 2 ppm for the first fluorine, 1.5 ppm for the second. For chlorinated ethers: add 1.8 ppm for the first chlorine, 1.4 ppm for the second. Taken from T.J. Bruno, P.D.N. Svoronos, CRC Handbook of Basic Tables for Chemical Analysis, CRC Press, Boca Raton, 1989.

The group contribution factors for substituents located in the a, [3, y, and 8 positions to the I3C nucleus of interest are provided in Table 12 for species of interest to alternative refrigerant analysis. I9

F NMR Absorptions I9 F NMR spectroscopy developed concurrently with 'H NMR because of the similarities of the two nuclei. The magnetic moment of I9 F is only slightly smaller than that of 'H, for example, and as a result the instrumental sensitivity of 19F NMR is very high. The major difference is the very large CS range that compounds exhibit in 19F NMR, typically 800 ppm (and even extends to 1000 ppm if one includes inorganic fluorides). The reason for this rather large range is that there is a strong paramagnetic component to nuclear shielding that is absent in the case of 'H. This paramagnetic component to the absorption frequency is a complicating factor in the prediction of the chemical shift. Indeed, the state of understanding of "F NMR chemical shifts is very incomplete. The usual standard in modern 19F NMR is TFM, but much of the older literature contains studies in which external standards or other internal standards were used. This standard compound (and the resulting CS scale) is due to the work of Filipovich and Tiers [57], and chemical shifts are often represented as when extrapolated to infinite dilution of solute, or * at higher concentrations. An approximate conversion of the chemical shifts measured with some other standards is provided in Table 13. CS values of nuclei that are shielded less than the fluorine in CC13F carry "+" signs, while those that are more shielded carry "-" signs. In addition, I9 F NMR spectra are strongly affected by the solvent that is used and by solution concentrations, far more so than either 'H or "C NMR spectra. For these reasons, correlations based on I9F NMR chemical shifts are not generally available. The spectra are extremely valuable as a fingerprint, however, because of the unique ability of 19F to spin couple to both 'H and 13C. Despite the difficulties in prescribing general correlations, some clear tendencies have been identified. For saturated compounds, a fluorine on a tertiary carbon absorbs at a high field, and the absorption decreases with fluorine substitution on the carbon. Thus, we have CH3F, -276 ppm, CH,-CH2F2, -215 ppm, and CF,-CF2-CF2-CF3, -84 ppm relative to TFM, where the absorption of the bold-faced fluorine is provided.

Chemical Analysis Methods for Alternative Refrigerants and Related Products

I3

25

TABLE 12 C NMR Chemical Shifts

The chemical shift (in ppm) for a particular "C nucleus on a molecule, "C;, can be predicted from:

is the sum of group contributions that are a, p, y. or 8 to 13C,. The group contributions provided here are in ppm relative to tetramethylsilane (TMS). Alkanes, Substituted Alkanes t;

Substituent

a

P

Y

5

>C >C=C< (sp2) OC- (sp) -F -Cl -Br -OR

9.1 19.5 4.4 70.1 31.0 18.9 49.0

9.4 6.9 5.6 7.8 10.0 11.0 10.1

-2.5 -2.1 -3.4 -6.8 -5.1 -3.8 -6.2

0.3 0.4 -0.6 0.0 -5.0 -0.7 0.0

Taken from TJ. Bruno, P.D.N. Svoronos, CRC Handbook of Basic Tables for Chemical Analysis, CRC Press, Boca Raton, 1989. 17

O NMR Absorptions An additional NMR nucleus worthy of mention in the study of fluorinated ethers is I7 O. The CS range for 17O NMR spectra is between 700 and 800 ppm for organic compounds. Although little work has been done on fluorinated ethers with this technique, one can expect an I7O CS change of up to 100 ppm for the substitution of each fluorine atom for a proton (hydrogen atom) on the a-carbon to the ether linkage. There are some major obstacles with 17O NMR, however. It has a very low (0.037 percent) natural abundance and, therefore, will have a low instrumental sensitivity. In addition, it possesses a quadrupole that will significantly broaden the observed absorptions. Spin-Spin Coupling In addition to the effect of the chemical shift on the absorption, the magnetic moment of each nucleus in different chemical environments on the molecule will influence the absorption of the other nuclei through the intervening bonds. Usually, the effect decreases rapidly with an increase in the number of intervening bonds. In effect, the spins of each type of nucleus will couple, producing a characteristic splitting of absorption lines on a spectrum. The magnitude of the splitting is called the coupling constant, J, and is expressed in hertz. Unlike the absorption frequency, these values are independent of the applied field strength. The major consequence of this field-independence is that spin-spin coupling patterns can, in some cases, be correlated and predicted. This allows them to be used for both identification and structural analysis. In this chapter, we will provide very general guidelines to employ spin-spin coupling to elucidate the NMR spectra of alternative refrigerant products. The detailed analysis of spin systems is a very complex undertaking, however, and the theory and interpretation is best left to several excellent treatises. Spin-spin coupling correlations will, nonetheless, be very useful

26

CRC Handbook for the Identification and Analysis of Alternative Refrigerants TABLE 13 Conversion Factors for Various 19 F NMR Standards CSCFC1,= CS C ( H 5 C F j -63 ppm = = = =

CSCFj - 64 ppm CSCFjCOOH - 77 ppm CSC F - 163 ppm CSF' + 430 ppm

to us, since all three of the nuclei of interest undergo spin-spin coupling. This is especially important for 'H and 19F because of their high abundance. The effect can be observed on the 'H spectrum of R-141b shown in Figure 2. Although there is only one kind of proton present (those on the -CH3 group that are chemically and magnetically equivalent), we do not see a singlet peak. The peak of the methyl protons is split because of the 'H-'9F spin-spin coupling. A summary of spin-spin coupling constants of value to the interpretation of NMR spectra of alternative refrigerant products is provided in Table 14 [34]. These are the JFH, JFCF, and JCF coupling constants. One should be aware that the solvent used can have some effect on the actual J that is measured, but it is usually within the range given in the table. A more extensive tabulation can be found in the book by Emsley [65]. CHROMATOGRAPHIC RETENTION PARAMETERS Gas chromatography is a dynamic separation method that consists of two media: a mobile phase called the carrier gas, and a nonmobile, stationary phase [68-84]. It is most often used as a quantitative analysis method applied to volatile and volatizable compounds. For this application, one depends upon the reproducible response of a detection device to individual separated compounds. It can also be successfully applied as a qualitative identification method by making use of various retention parameters. In this respect, it is often a very cost-effective method for identification owing to the simplicity and economics of gas chromatography. The retention time or volume (that is, the retention time multiplied by the corrected carrier gas flow rate) of a particular solute on a particular stationary phase, measured under controlled conditions, is often a very useful indication of the identity of a compound. When the retention is measured at two or more temperatures or on more than one stationary phase (of significantly different polarity), identification is often possible with a high level of confidence by comparison with known, standard data measured on the same stationary phase(s). [Admittedly, retention parameter measurement on two separate columns is tedious and time consuming.] To apply gas chromatography in this way, it is necessary to carefully duplicate instrumental conditions that were used to generate the reference data, or preferably to correct for them, thus making the measurements instrument-independent. The most important instrumental conditions that must be considered are column temperature, carrier-gas flow rate, column head pressure and pressure drop, sample size effects, and the quantity and chemical nature of the stationary phase. Some notes of caution are in order before we consider the application of gas chromatography as a qualitative identification method. It is important to understand that the results obtained from retention data are necessarily indirect. The equality of retention times of two materials (measured under the same conditions of column temperature carrier-gas flow rate and stationary phase) does not constitute positive proof that the two materials are the same. One can make the absolute statement to the contrary, however. That is, if the retention times of two materials are different under the same conditions, and the instrument is functioning properly, one can be certain that the two materials are indeed different. One must also understand that a chromatographic peak may contain detector-response contributions from more than one material, even if the peak shape is considered favorable (that is, no fronting or

Chemical Analysis Methods for Alternative Refrigerants and Related Products

27

TABLE 14 Fluorine Coupling Constants Useful for the Interpretation of NMR Spectra of Alternative Refrigerants I9

Fluorinated Family Two—bond Alkanes

Examples

J FH

45-80

Alkyl chlorides Alkyl bromides Alkenes

49-65 45-50 45-80

Ethers

40-75

F-H Coupling Constants

CH,F (45); CH2F2 (50); CF,H (79); C,H,F (47); CH,CHF2 (57); CH,FCH,F (48); CH2FCHF, |JCHiF=46; J rHFi =54]; CF,CH2F (45); CF,HCF2CF, (52) CFHC1, (53); CF,HC1 (63); FCHC1CHC1, (49); FCH2CH,C1 (46) FCHBrCH, (50.5); FCH,CH,Br (46); FCHBrCFHBr (49) CHF=CHF (m-71.7; wa/w-75.1); CH2CHF (85); CF 2 =CHF (70.5); FCH 2 CH=CH, (47.5) CF,HOCH, (74); FCH,CF,OCH, (46); CF,HOCH(CH,)2 (75); CF2HCF2OF (56) "F-I9F Coupling Constants Examples

J KCK Two-bond Saturated (sp1)

Unsaturated (sp 2 )

Three-bond Saturated (sp-1)

Unsaturated (sp 2 )

140-250

100

0-16

>30

CF,CF2a "CFHCH, (J. lb = 270); CF/-bBrCHFSO2F (J ab = 188); CF,O-CF2a bCFHSO2F (J.lb = 147); CH,O-CF 2 ab CFHCl (J. lb = 142); CH,S-CF 2 » b CFHCl (J ah = 222) CF,=CH 2 (31,36); CF 2 =CHF (87); CF,=CBrCl (30); CF2=CHC1 (41); CF 2 =CFBr (75); CF,=NCF, (82); CF2=CFCN (27); CF2=CFCOF (7); CF2=CFOCH,CF3 (102); CF 2 =CBrCH 2 N(CF,) 2 (30); CF2=CFCOCF,CF, (12); CF2=CHC,,H5 (33); CF 2 =CH(CH 2 ) 5 CH, (50) CF,CH,F (16); CF,CF, (3.5); CF,CHF2 (3); CH 2 FCH 2 F (10-12); CFv'HCFhHCF2H (J ah =13); CF2HCF2"CH2Fb (J ab =14); CF3aCF,bCFcHCH, (J ab halocarbons in ambient air by cold trap injection and wide bore glass capillary gas Chromatography, Anal. Chem., 323, 334-339, 1986. 105. Nikitin, Y.S., Viryasov, M.B., Gas Chromatography of low molecular weight halocarbons on macroporous silica modified by a thin liquid phase film, Chromatographia, 21(12), 681-686, 1986. 106. Noij, T., Fabian, P., Borchers, R., Cramers, C., Rijks, J., Trace analysis of halogenated hydrocarbons in gaseous samples by capillary gas Chromatography. Part II. Quantitative aspects and ECD calibration, Chromatographia, 26, 149-156, 1988.

Chemical Analysis Methods for Alternative Refrigerants and Related Products

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107. Noij, T., Rijks, J.A., Cramers, C.A., Problems caused by the activity of AUO,-PLOT columns in the capillary gas chromatographic analysis of volatile organic compounds, Chromatographia, 26, 139-141, 1988. 108. Harsch, D.E., Cronn, D.R., Low-pressure sample-transfer technique for analysis of stratospheric air samples, ,/. Chromatogr. Sri., 16, 363-367, 1978. 109. Simmonds, P.O., Kerns, E., Direct aqueous injection gas chromatography for the analysis of trace organics in water,/. Chromatogr., 186, 785-794, 1979. 110. Goldan, P.D., Fehsenfeld, F.C., Kuster, W.C., Phillips, M.P., Sievers, R.E., Vinyl chloride detection at subparts-per-billion levels with a chemically sensitized electron capture detector, Anal. Chem., 52. 1751-1754. 1980. 111. Makide, Y., Yokohata, A., Tominaga, T., Ultratrace analysis of CCI 2 F 2 , CC1,F, CC1,FCC1F2, CH,CC1,, CCI4, CHC1* CC1,, and CC12* CC1, in the atmosphere, J. Trace and Micmpmbe Techniques, 1(3), 265-292, 198283. 112. Nicholson, B.C., Bursill, D.B., Couche, D.J., Rapid method for the analysis of trihalomethanes in water, ./. Chromatogr.. 325, 221-230, 1985. 113. Bachmann, K., Pol/er, J., Determination of tropospheric phosgene and other halocarbons by capillary gas chromatography,/. Chromatogr.. 481, 373-379, 1989. 114. Bruno, T.J., Vortex cooling for subambient temperature gas chromatography, Anal. Chem., 58, 1596, 1986. 115. Grob, K., Grob, G., Capillary columns with very thick columns. /. High Res. Chromatogr. & Chromatogr. Comm.. 6. 133, 1983. 116. Bruno, T.J., Apparatus and method for the evaporative concentration of liquid samples. United States Patent No. 5.217.904, June 8, 1993. 117. Bruno, T.J., Simple, inexpensive apparatus for sample concentration, /. Chem. Educ., 69(10). 837, 1992. 118. Bruno, T.J., Chromatographic cryofocusing and cryotrapping using the vortex tube, /. Chromatogr. Sri.. 32. 112-115, 1994. 119. Kumar, R., Effect of freon-12 exposure on the sieving property of 4A zeolite, Can. J. Chem. Eng., 60, 577, 1982. 120. Bruno. T.J., A simple gas sampling and injection apparatus../. Chromatogr. Sri., 23, 325, 1985. 121. loffe, B.V., Vitenberg, A.G., Head-Space Analysis and Related Methods in Gas Chromatography, WileyInterscience, New York, 1982. 122. Sam, C.T., Chua, T.H., Chlorofluorocarbon (CFC) determination in styrofoam ware by headspace gas chromatography and GC-mass spectrometry. Bull. Sing. N.I. Chem., 17, 65-7, 1989. 123. Freiria-Gandara, M.J., Alvarez-Devesa, A., Lorenzo-Ferreira, R.A., Bermejo-Martinez, F., Identification and determination of halogenated hydrocarbons in waters of Galicia (N.W. Spain) by headspace gas-chrornatogn\phy. Anal. Letters, 23(10), 1939-1958, 1990. 124. Kolb. B.. Application of gas chromatographic head-space analysis for the characterization of non-ideal solutions by scanning the total concentration range, /. Chromatogr., 112, 287-295, 1975. 125. Steichen, R.J., Modified solution approach for the gas chromatographic determination of residual monomers by head-space analysis, Anal. Chem., 48(9), 1398-1402, 1976. 126. Piet, G.J., Slingerland, P., deGrunt, F.E., v.d. Huevel, M.P.M., Zoeteman, B.C.J., Determination of very volatile halogenated organic compounds in water by means of direct head-space analysis, Anal. Letters, A l l ( 5 ) . 437-448, 1978. 127. Dietz. Jr., E.A.. Singley, K.F.. Determination of chlorinated hydrocarbons in water by headspace gas chromatography. Anal. Chem.. 51(11), 1809-1814, 1979. 128. Kolb, B., Auer, M., Pospisil. P.. Methods for the quantitative analysis of volatile halocarbons from aqueous samples by equilibrium headspace gas chromatography with capillary columns,/. Chromatogr. (Chromsymp. 183), 341-348, 1983. 129. Laub. R.J., Pecsok, R.L., Physicochemical Applications of Gas Chromatography. Wiley-lnterscience, New York. 1978. 130. Conder, J.R.. Young. C.L.. Physicochemical Measurement by Gas Chromatography. Wiley-lnterscience, Chichester. 1979. 131. Hager, M., Baker, G., Proc. Mont. Acad. Sri., 22, 3, 1962. 132. Harris, D.C., Quantitative Chemical Analysis, 2nd. ed., W.H. Freeman Co., New York, 1987. 133. Hydraual Manual — Eugcn Scholz Reagents for Karl Fischer Titration. Riedel-deHaen, Seel/.e, 1988. 134. Baustian. J.J.. Pate. M.B., Bergles, A.E., Measuring the Concentration of a Flowing Oil-Refrigerant Mixture with a Vibrating U-Tube Densimeter, ASHRAE Trans.. No. 3179 (RP-356). p. 571. 1979. 135. Baustian, J.J., Pate. M.B., Bergles. A.E., Measuring the Concentration of a Flowing Oil-Refrigerant Mixture with an Acoustic Velocity Sensor, ASHRAE Trans.. No. 3181 (RP-356), p. 602, 1981. 136. Baustian, J.J., Pate, M.B., Bergles, A.E.. Measuring the Concentration of a Flowing Oil-Refrigerant Mixture with Bypass Viscometer, ASHRAE Trans.. No. 3180 (RP-356), p. 588. 1980. 137. Kutsuna. K., Yoshimitsu, I., Mizutani, T.. Sudo, E., Araga. T.. SAE Tech. Pap. Ser. No. 910222 (presented at the International Congress and Exposition, Detroit, MI, 1991).

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CRC Handbook for the Identification and Analysis of Alternative Refrigerants

138. Walraevens, R., Trouillet, P., Devos, A., Basic elimination of HC1 from chlorinated ethanes, Int. J. Chem. Kinetics. 6. 777-786, 1974. 139. Bruno, T.J.. Hume, G.L., A high temperature, high pressure reaction-screening apparatus, Nat. Bur. Stand. (U.S.). J. Res.. 90(3), 255-257, 1985. 140. ASME Boiler and Pressure Vessel Code, Sect. VIII: Unfired Pressure Vessels (American Society of Mechanical Engineers), New York, 1965. 141. Bruno, T.J., Straty, G.C., Thermophysical property measurement on chemically reacting systems — A case study, Nat. Bur. Stand. (U.S.) J. Res.. 91(3), 135-138, 1986. 142. Tschuikow-Roux, E., Thermal decomposition of fluoroform in a single-pulse shock tube. II. Pressure dependence of the rate, /. Chem. Phys., 42(10), 3639-3642, 1965. 143. Tschuikow-Roux, E., Matte, J.E., Thermal decomposition of fluoroform in a single-pulse shock tube. I, ./. Chem. Phys., 42(6), 2049-2056, 1965. 144. Tschuikow-Roux, E., The C-C bond dissociation energy in C2Fi, /. Phys. Chem., 69, 1075, 1965. 145. Tschuikow-Roux, E., Kinetics of the thermal decomposition of C2F6 in the presence of H, at 1300°-1600° K, /. Chem. Phys.. 43(7), 2251-2256, 1965. 146. Simmie, J.M., Tschuikow-Roux, E., Thermal decomposition of vinylidene fluoride behind reflected shock waves, Chem. Comm., 773, 1970. 147. Simmie, J.M., Quiring, W.J., Tschuikow-Roux, E., Kinetics of the dehydrofluorination of vinyl fluoride in a single-pulse shock tube, J. Phys. Chem., 74, 992, 1970. 148. Tschuikow-Roux, E., Quiring, W.J., Simmie, J.M., Kinetics of the thermal decomposition of 1,1 -difluoroethane in shock waves. A consecutive first-order reaction, J. Phys. Chem., 74, 2449, 1970. 149. Simmie, J.M., Tschuikow-Roux, E., Kinetics of the shock-initiated decomposition of 1,1-difluoroethylene, J. Phys. Chem.. 74, 4075, 1970. 150. Tschuikow-Roux, E., Simmie, J.M., Quiring, W.J., A re-examination of the single-pulse shock tube technique: determination of reflected shock temperature, Astronautica Ada, 15, 511-521, 1970. 151. Tschuikow-Roux, E., Quiring, W.J., Kinetics of the thermally induced dehydrofluorination of 1,1,1trifluoroethane in shock waves, J. Phvs. Chem.. 75, 295, 1971. 152. Millward, G.E., Hartig, R., Tschuikow-Roux, E., Hydrogen fluoride elimination from shock-heated 1,1,2,2tetrafluoroethane, Chem. Comm., 465, 1971. 153. Millward, G.E., Hartig, R., Tschuikow-Roux, E., Kinetics of the shock wave thermolysis of 1,1,2,2tetrafluoroethane,,/. Phys. Chem., 75, 3195, 1971. 154. Millward, G.E., Tschuikow-Roux, E., A kinetic analysis of the shock wave decomposition of 1,1,1,2tetrafluoroethane,./. Phys. Chem., 76, 292, 1972. 155. Millward, G.E., Tschuikow-Roux, E., The competitive dehydrohalogenation of 1,1,1 -trifluoro-2-chloroethane in reflected shock waves, Int. J. of Chem. Kinetics, IV, 559-571, 1972. 156. Sekhar. M.V.C., Millward, G.E., Tschuikow-Roux, E., Kinetics of the thermal decomposition of CF,CHC12 in a single-pulse shock tube, Int. J. of Chem. Kinetics, V, 363-373, 1973. 157. Sekhar, M.V.C., Tschuikow-Roux, E., Competitive a,oc- and a,(3-dehydrohalogenations from CH,CDF2 behind shock waves,/. Chem. Soc. Chem. Comm.. 137, 1974. 158. Sekhar, M.V.C., Tschuikow-Roux, E., Kinetics of the shock-induced competitive dehydrofluorinations of 1,1,2-trifluoroethane,,/. Phys. Chem., 78, 472, 1974. 159. Evans, P.J., Ichimura. T., Tschuikow-Roux, E., A comparison of two single-pulse shock-tube techniques: the thermal decomposition of ethyl chloride and n-propyl chloride. Int. J. of Chem. Kinetics. 10(8), 855-869,1978. 160. Okada, K., Tschuikow-Roux, E., Evans, P.J., Single-pulse shock-tube study of the thermal decomposition of ethyl fluoride and n-propyl chloride,,/. Phys. Chem.. 84, 467, 1980. 161. Kirk, A.W., Tschuikow-Roux, E., Vacuum ultraviolet photolysis of fluoroethylenes. I. vinyl fluoride at 1470 A,/. Chem. Phys.. 54(5), 1924-1930, 1970. 162. Chan, S.C., Inel, Y., Tschuikow-Roux, E., Primary processes in the vacuum ultraviolet photolysis of ethyl fluoride at 147 nm, Canadian J. Chem., 50(10), 1443-1447, 1972. 163. Ichimura, T., Kirk, A.W., Kramer, G., Tschuikow-Roux, E., Photolysis of ethyl chloride (Freon 160) at 147 nm,./. Photochcm., 6, 77-90, 1976/77. 164. Ichimura, T., Kirk, A.W., Tschuikow-Roux, E., Photolysis of 1,1,1-difluorochloroethane (Freon 142) at 147 nm, Int. J. Chem. Kinetics. IX, 697-703, 1977. 165. Salomon, D., Kirk, A.W., Tschuikow-Roux, E., Primary processes in the photochemical decomposition of 1,1,1-trichloroethane at 174 nm,./. Photochcm.. 1. 345-353, 1977. 166. Ichimura, T.. Kirk, A.W.. Tschuikow-Roux. E.. Vacuum ultraviolet (147 nm) photolysis of 1,2fluorochloroethane. Int. J. Chem. Kinetics, IX, 743-749, 1977. 167. Ichimura. T.. Kirk, A.W., Tschuikow-Roux, E.,The 123.6-nm photolysis of 1,2-fluorochloroethane and 1,1,1difluorochloroethane,./. Phys. Chem.. 81, 2040, 1977. 168. Salomon, D., Kirk, A.W., Tschuikow-Roux, E., Primary processes in the 147-nm photolysis of 1.1dichloroethane. Int../. Client. Kinetics. 9(4). 619-628, 1977.

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169. Ichimura, T., Kirk, A.W., Tschuikow-Roux, E., Primary processes in the 147- and 123.6-nm photolyses of l,l,l-trifluoro-2-chloroethane,/. Phys. Chem., 81, 1153, 1977. 170. Yano, T., Tschuikow-Roux, E., Photodecomposition of 1,1 -difluoro-1,2-dichloroethane at 147 nm,./. Phys. Chem., 83, 2572, 1979. 171. Salomon, D., Kirk, A.W., Tschuikow-Roux, E., Primary processes in the 147-nm photolysis of 1,2dichloroethane, /. Phys. Chem., 83, 2569, 1979. 172. Yano, T., Tschuikow-Roux, E., A reexamination of the photodissociation of CH2C1CH,C1 at 147 nm. Test for chlorine atom reactions, /. Phys. Chem.. 84, 3372, 1980. 173. Yano, T., Jung, K.H., Tschuikow-Roux, E., Photodissociation of 1,1,1 -trifluorodichloroethane at 147 nm. Evidence for chlorine atom reactions, /. Phys. Chem., 84, 2146, 1980. 174. Yano, T., Tschuikow-Roux, E., Vacuum-ultraviolet (147 nm) photodecomposition of 1,1,2-trichloro-2,2difluoroethane,./. Chem. Phys., 72(5), 3401-3409, 1980. 175. Yano, T., Tschuikow-Roux, E., Competitive photochlorination of the fluoroethanes CH,CHF2, CH2FCH2F, and CHF,CHF2, J. Photochem., 32, 25-37, 1986. 176. Tschuikow-Roux, E., Nied/.ielski, J., Faraji, F., Competitive photochlorination and kinetic isotope effects for hydrogen/deuterium abstraction from the methyl group in C2H6, C,D6, CH,CHC1,, CD,CHC13, and CD,CC13, Canadian./. Chem., 63(5), 1093-1099, 1985. 177. Yano, T., Ozaki, S., Ogura, S., Tschuikow-Roux, E., Infrared laser multiphoton dissociation of CF,C1CH,C1, J.Phys. Chem., 89, 1108, 1985. 178. Tschuikow-Roux, E., Yano, T., Niedzielski, J., Reactions of ground state chlorine atoms with fluorinated methanes and ethanes, /. Chem. Phys.. 82(1), 65-74, 1985. 179. Niedzielski, J., Tschuikow-Roux, E., Secondary kinetic isotope effects: deuterium abstraction by chlorine atoms from the CD3 group in CD,CH,CL, CD,CHDC1, and CD,CD,C1, Chem. Phys. Letters, 105(5), 527-530, 1984. 180. Tschuikow-Roux, E., Yano, T., Niedzielski J., Photochlorination of chloroethane and chloroethane-d5,./. Phys. Chem., 88, 1408, 1984. 181. Niedzielski, J., Tschuikow-Roux, E., Yano, T., Hydrogen/deuterium abstraction by chlorine atoms from gaseous ethyl chlorides. Secondary kinetic isotope effects in the system CH3CH,C1, CH,CHDC1, CH,CD,C1, J. Chem. Kinetics, 16, 621-631, 1984. 182. Tschuikow-Roux, E., Niedzielski, J., Secondary kinetic isotope effects in hydrogen and deuterium abstraction by chlorine atoms from the chloromethyl group in gaseous ethyl chlorides: effects of isotopic substitution in the adjacent methyl group, /. Photochem.. 27, 141-150, 1984. 183. Niedzielski, J., Yano. T., Jung, K.H., Tschuikow-Roux, E., Kinetic isotope effects in the photochlorination of gaseous ethyl chloride-2-d,, J. Photochem., 27, 151-161, 1984. 184. Niedzielski, J., Yano, T., Tschuikow-Roux, E., Primary kinetic isotope effect in the gas phase photochlorination of ethyl chloride-1-d,, Canadian J. Chem., 62(5), 899-906, 1984. 185. Tschuikow-Roux, E., Faraji, F., Niedzielski, J., Rate constants and kinetic isotope effects for hydrogen/ deuterium abstraction by chlorine atoms from the chloromethyl group in CH2C1CH,C1, CD2C1CD,C1, CH2CICHC12, and CH,C1CDC12, //;/. /. Chem. Kinetics, 18(5), 513-527, 1986.

Chapter 2

ANALYTICAL DATA FOR ALTERNATIVE REFRIGERANTS AND RELATED MATERIALS Thomas J. Bruno, Brian N. Hansen, Michael Caciari Thermophysics Division National Institute of Standards and Technology Boulder, CO 80303 Paris D. N. Svoronos Department of Chemistry Queensborough College of City University of New York Bayside, N.Y. 11364 Robert F.X. Klein, T. Christopher Waidner Department of Chemistry Georgetown University Washington, B.C. 20057

INTRODUCTION The accurate identification and quantitation of alternative refrigerant fluids and related materials are dependent on a reliable and complete base of analytical information that has been measured on compounds of well-known purity and physical characteristics. In this chapter, we provide a compilation of physical property data, spectra, and chromatographic information that is helpful in the analysis of alternative refrigerants, potential reaction products, and related materials. The data are arranged in short sections for each compound. Each section begins with some basic physical property and safety information, and the analytical information follows on subsequent pages. The physical property and safety information on the introductory pages are separated by a line of asterisks. The physical property data page begins with the chemical name and code number for each compound. A list of some common synonyms are then provided. The reader might note that these synonyms may sometimes be older generic or commercial names that are no longer considered proper chemical nomenclature, or even obviously incorrect names that have often appeared in various sources. They are provided because some of the older literature and product literature may occasionally contain these names, but we strongly recommend the use of the applicable IUPAC nomenclature. The chemical structure, Chemical Abstracts Service registry number (if available), and the relative molecular mass are then provided.

PHYSICAL PROPERTIES Wherever possible, the physical property data listed here have been obtained from reliable literature sources of known standing in the scientific community [1-9]. In addition to these sources, research papers in the open literature that deal with these fluids were also searched and consulted, and are referenced in Chapter 1. Each of the listed sources was consulted and cross-checked for each datum. This process led to the inevitable rooting out of some questionable data. These discrepancies among reported property values were researched until resolved, a process that very occasionally involved remeasurement. In this respect, this work serves as a screening tool for the physical property data. In some cases, where little or no data were 57

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available, the values of physical properties were measured specifically for this compendium or were estimated theoretically. For example, all of the chromatographic retention parameters and many of the refractive indices were measured for this chapter. Moreover, many of the critical properties and some of the vapor densities were calculated from appropriate predictive models. More details on these instances are provided in the discussion of each property that is presented. The physical properties listed for these compounds include the normal boiling temperatures, melting point temperatures, critical parameters, densities (or specific gravities), acentricities and dipole moments. The normal boiling point temperature is the temperature at which a compound boils under 0.101 325 MPa (760 mm of mercury or 760 Torr, 1.013 25 bar, or 14.696 lbs/in2) pressure. It is an important indicator of the volatility of a material. In very rare circumstances, the normal boiling point of an individual compound was unavailable and had to be estimated by group contribution methods [4]. These predicted boiling point values are marked with an asterisk (*). The critical properties or parameters of a fluid include the critical temperature, Tc, the critical pressure, Pc, the critical density, pc (or its reciprocal, the critical volume, V c ). The critical temperature is the temperature above which a fluid cannot be liquefied, despite the magnitude of the applied pressure. At this point, the liquid and gaseous phases of the fluid become indistinguishable. The critical pressure and the critical density are the values of the fluid pressure and density, respectively, at the critical temperature. The intersection of these quantities on the P-V-T diagram of the fluid is called the critical point. The tabulated critical properties were taken from literature sources of measurements, where possible. In some instances, experimental values were not available, and the critical constants were estimated by Joback's modification of the Lyderson group contribution method [4|. These predicted values are marked with an asterisk (*). In a few instances, predicted critical constants were found in the literature and were used in the tabulations presented here. These values are marked with a double asterisk (**). The critical constants are important for several reasons: they are important design parameters for many refrigerant applications, and they are important when considering the use of many of these fluids as solvents in the supercritical fluid region. Densities and specific gravities were obtained from literature sources [1-9]. The temperatures corresponding to these values are included in parentheses. Occasionally, a liquid density is reported at a temperature above the boiling point of fluid, or under two-phase conditions where a gas and a liquid can exist. In these cases, this is the coexisting liquid density and is indicated as such by the script letter "1". All other values of the density or specific gravity are at atmospheric pressure. These values are important in the design of analytical schemes and separations, and can sometimes be useful for qualitative identification. The refractive index, nD, of a substance is the ratio of the velocity of light in a vacuum relative to the velocity of light in the substance. It is dependent upon temperature, the wavelength of the light used for the measurement, and the chemical nature of the material itself. Because of this strong material dependence and the high accuracy of measurements performed with even simple instruments (one part in 10,000), the refractive index of a substance has always been a good qualitative identification parameter. The refractive indices reported in these tables were taken from the literature where possible, or measured with an Abbe-type refractometer for some of the newer fluids for which no data were available [10]. The temperature for each refractive index value is indicated in parentheses. Often these measurements were made at relatively low temperatures because of the volatility of the fluids. The acentricity, co, of the fluid molecule (also called the acentric factor or Pitzer acentricity) is an indication of the microscopic complexity of a molecule. It is an important factor used in most useful equations of state. It is defined as:

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59

where Pv r is the vapor pressure in reduced form (that is, divided by the critical pressure), and Tr is the reduced temperature, defined as the thermodynamic temperature divided by the critical temperature (in kelvins) of the fluid. The acentricities of the materials were either obtained from literature sources [4] or calculated from vapor pressure data. The dipole moment of a polar molecule is the fractional charge (in electrostatic units, esu) multiplied by the distance in centimeters that separates the charges along the long axis of a molecule. It is therefore an indication of the polarity of the molecule. It is useful in designing solvent systems and in the selection of chromatographic stationary phases for analyses. Another use for the dipole moment stems from the usefulness of many alternative refrigerants as supercritical fluid solvents. In this respect, the dipole moments provide guidance in choosing an effective solvent from among those listed in this volume. In these tables, the dipole moment is provided in the familiar Debye units, defined as 10~ls multiplied by the charge (in esu) multiplied by the separation distance in centimeters. The last entry of physical properties is an indication of the common solvents (including water) in which the compound is soluble. Where possible, approximate solubility limits are provided. These data are taken from the literature where possible [1-3,6,9,11], but in some cases were determined in the course of this work. This information is essential in designing effective chemical analyses.

SAFETY INFORMATION Throughout this volume, the safe handling of alternative refrigerants and their products has been strongly emphasized. For this reason, the sources of safety information are provided in an appendix rather than simply listed with the references at the end of the chapter. It is of the utmost importance that the strictest safety guidelines be followed in performing the chemical analysis of these materials. We have, therefore, provided information on some of the hazards associated with some of these fluids. It must be understood that concepts such as toxicity and reactivity are very difficult to accurately quantitate since they usually represent very complex interactions. Safety information must be interpreted with caution, and the information presented here should be regarded as general guidelines. The vapor density of a gas or vapor is a kind of specific gravity with respect to air as a standard (defined to have a vapor density = 1) at a specified temperature and pressure. The temperature and pressure are chosen to be close to ambient conditions. The vapor density is sometimes approximated by the ratio of the relative molecular mass of a fluid to that of air, which is taken as 29. The values that were calculated by this method rather than measured are indicated by an asterisk in these tables. The vapor density is an important guideline in determining the course of action to follow immediately after the release of a quantity of the vapor or gas. It indicates the relative tendency of the material's vapor plume (resulting, for example, from an accidental spill) to drop to floor level in still (nonturbulent) air. The PEL is the permissible exposure limit. It is the legal workplace limit for exposure to a chemical (determined by OSHA, the Occupational Health and Safety Administration, Department of Labor, in the United States) that can never be lawfully exceeded. It can be expressed as a time-weighted limit or a ceiling exposure limit. The TLV, or threshold limit value, is a term used by the ACGIH (American Conference of Government Industrial Hygienists in the United States). It is the airborne concentration of a material to which nearly everyone may be exposed day after day without any known adverse effects. We have presented time-weighted average numbers here (TWA), expressed in terms of a normal 8-hour workday or 40-hour work week. Persons who are very young, very old, or who have certain illnesses may, of course, require the observance of more stringent limits.

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The flash point is the temperature at which a flammable fluid will form a mixture with air that is sufficiently flammable to ignite at the surface of the liquid. The usual measurement methods employ the Tagliabue open cup (OC, sometimes written as the Tag open cup or TOC), the Cleveland open cup (COC), or the closed cup (CC). Where possible, the flash point measurement method is given in parentheses along with the value. The upper and lower explosion limits of a material (abbreviated UEL and LEL) define the concentration regions between which a fluid can form a mixture with air that will detonate upon exposure to a flame or spark under ambient temperature and pressure. Detonation is distinguished from deflagration in that a shock wave (or pressure wave) emanates from the source of the reaction upon detonation, and is therefore very destructive. In an enclosed space this is especially hazardous, because the shock wave can be reflected back into the source of the explosion. This reflection produces a compression wave that can cause a secondary explosion that is more intense than the initiation explosion. At the extremes of the UEL and LEL ranges, the flame front may often be very weak, and the effects of fluid impurities and surfaces are more pronounced. The toxicology of a given substance is a very complex topic because it encompasses the many parameters that affect how a chemical substance interacts with a variety of living organisms. In these tables, we have included information gathered from material safety data sheets, as well as all of the sources listed in Appendix I. The literature on the toxicological properties of these materials can often be uncertain. Occasionally, for example, toxic effects are reported to occur at a "high" concentration of a given fluid. The quantitative aspect of "how high is high" is often left unresolved in the literature. In addition, inconsistencies between toxicological information sources is a serious and general problem. Moreover, some of the information may on first glance appear conflicting. As an example, we can consider the toxicological information presented for R-161, fluoroethane, reported in this volume as: "can cause pulmonary edema; narcotic at high concentration; simple asphyxiant". The term "simple asphyxiant" may appear inconsistent with the other information. A simple asphyxiant, as distinct from a chemical asphyxiant, is hazardous because of its ability to displace oxygen from air, causing the normal 21 percent concentration to fall to 18 percent or lower. A "chemical asphyxiant", on the other hand, chemically reduces the body's ability to carry or utilize oxygen. Examples of chemical asphyxiants are carbon monoxide (which binds to hemoglobin and prevents oxygen uptake) and the cyanide ion (which interferes with the body's ability to use oxygen). It is certainly possible that R-161 can be present in a high enough concentration to potentially cause narcosis in some persons, yet not decrease the oxygen level below 18 percent. In this respect, the statements are actually not in conflict with one another. Another factor that one must consider is the widely varying reactions that chemical substances can cause in different individuals. A vapor that causes narcosis in some persons may have little effect on others. It is not uncommon, in fact, for some fraction of the adult population to react in a way completely different from the majority upon exposure to some chemicals. Some chemicals that act as anesthetics in most people can, at the same concentration, make others very wakeful and nervous. In compiling the information on toxicology and health hazards, we have adopted a philosophy of encouraging a high level of laboratory caution, even at the risk of presenting information that has not yet been subjected to a full critical evaluation. Our purpose in presenting a summary from all current sources is to provide the analyst with as complete a slate as possible of potential problems. The chemical incompatibilities and reactivities include information from material safety data sheets, the sources listed in Appendix I, and reports in the literature that deal with topics other than safety, but in which a reference to a particular hazard or hazardous event has been mentioned. Many of the references cited in Chapter 1 of this volume contain such information. In many cases, special circumstances are required to cause the incompatibility to be manifested.

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This often includes the requirement that one of the incompatible species be a finely divided metal or that the temperature of the material be high. This admittedly leaves many questions unanswered, such as how fine is "fine", and how hot is "hot". These questions are largely unresolved in the literature, especially with respect to the newer compounds. Moreover, a small fraction of the information on chemical incompatibilities is anecdotal rather than the result of sound scientific investigation. On balance, however, we feel it is safer to provide an indication of what might be possible, even if such reactions may be unlikely under many circumstances.

ANALYTICAL DATA The analytical information presented in this chapter includes measurements of mass spectra, infrared spectra, ultraviolet spectra, nuclear magnetic resonance spectra (on 'H, I3 C and 19F nuclei, wherever possible), and chromatographic retention parameters [11-17]. Measurements were performed on materials of the highest available purity; however, some samples did contain impurities at appreciable levels. In some cases of gaseous samples, the impurities have a higher solubility in common solvents than the compound of interest. In a few of these cases, certain spectra were deleted because of the interference of impurities, especially NMR spectra that had to be measured in solution. No purification was done on the samples, since it is desirable to have measurements on materials that would typically be used in an industrial setting, especially if the spectral features of the impurities can be identified. An example of this would be the associated or polymerized compounds that are present as impurities in the ethene-based fluids. These obvious structural features are noted on the appropriate spectra. Naturally, since gas chromatography is a separation technique, the retention parameter measurements are unaffected by the presence of impurities in the sample. The mass spectra were recorded with a mass-selective detector interfaced to a capillary column installed in a gas chromatograph. In this way, the effects of impurities on the mass spectra are avoided by prior separation. The column employed for the separation was a 30 m fused quartz capillary coated with a 1 u,m layer of polymethyl siloxane to provide separation based on boiling point. The mass spectrometer was operated in electron-impact mode, and the relative molecular mass range from 15 to 330 was scanned continuously. Mass filtration was provided by a quadrupole sector. Calibration and tuning of the mass spectrometer was done with perfluorotributyl amine as the reference compound. The more volatile fluids were injected with a gas-tight syringe directly into a split/splitless injector (set for a 10/1 split), while the less volatile gases and liquids were injected as dilute solutions in carbon tetrachloride. The mass spectra are presented as normalized histograms of total ion current or intensity versus ion fragment mass/charge ratio. They are also tabulated as mass/charge ratio versus ion current (in arbitrary units) for each fragment. It must be understood that these values are guidelines only, and other instruments will clearly give different ion currents. The main value of this tabulation is for ratio calculations between ion fragments. For clarity, ubiquitous impurity peaks such as those for water (m/e = 18), carbon dioxide (m/e = 44), oxygen (m/e = 32), and nitrogen (m/e = 28) have not been included in the mass spectra that are presented. It should also be pointed out that in most cases, peaks at m/e ratios of between 30 and 35 are usually omitted from the histogram but are included in the tabulation. We recall from part 1 that the lighter fragments have a much lower information content than the heavier fragments. For this reason, we have chosen to "sanitize" the histograms. The infrared spectra were obtained with a ratio-recording, energy-dispersive spectrophotometer operating in the mid-IR region of the spectrum. Sodium chloride optics were used on all sample cells. Neat samples were measured either with a liquid cell (0.025 mm path length), a gas cell (10cm path length), or a chilled liquid cell (0.025 mm path length). Solution spectra were measured in carbon tetrachloride in a standard liquid cell or a chilled liquid cell (each having a 0.025 mm path length), or in the absence of solvent. The choice between these two

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alternatives was made on the basis of convenience, sample scarcity, and safety in sample handling. The sample cells are described in more detail in Chapter 1. The spectral reference in each case was air. The physical state of the sample is indicated with the spectrum. The ultraviolet-visible spectra were obtained on a single-beam, diode array spectrophotometer having a deuterium lamp and a tungsten lamp for the UV and visible regions, respectively. For fluids that are liquids under ambient conditions, a standard 1 cm path-length quartz cuvette was used as the sample holder. For the gases and higher-vapor-pressure liquids, a high-pressure cell (described in more detail in Chapter 1) was used. In addition to the spectra, the maximum absorbance (Abs,max.), the wavelength of the maximum absorption (A.,max.), and the wavelength of the absorption cut off (X,cut off) are provided. In cases where there are no discernable maxima (that is, the material presents an essentially transparent path to the UV-vis beam, or maxima cannot be distinguished from noise), these data are omitted. Nuclear magnetic resonance spectra were obtained at room temperature in standard 5 mm quartz NMR tubes on a spectrometer operating at 300.13 MHz. Samples prepared for 'H and 19F NMR spectra were dissolved in CDC13 (chloroform-d). Liquid compounds were prepared in concentrations of approximately 2 percent (mass/mass). Gaseous compounds were prepared by cooling 2 mL CDC1, (in the NMR tube) in an ice bath for 5 minutes. The gas was bubbled into the CDC1, for 2 minutes, and the tube was sealed. The exact concentrations of these solutions were, of course, unknown. In some cases, insufficient sample was soluble in the solvent to allow the spectrum to be recorded, or the solubilities of impurities were higher than that of the sample. These spectra are omitted. The absence of these spectra in this compilation is not considered a serious disadvantage, since having the spectrum here would be of marginal value if heroic measures are required to reproduce it for study in other laboratories. The chemical shifts for the 'H and 19F NMR are reported in parts per million with tetramethylsilane (TMS) and trichlorofluoromethane (TFM) used as an internal standards, respectively. In some cases, where the spectra are complex, an expanded scale spectrum is presented of the peak multiplets, and sometimes the absorptions are reported as frequencies (Hz). The reader should note the presence of some very common impurities on the 'H spectra. These are the peaks for water (a singlet at approximately 1.5 ppm) and residual chloroform (a singlet resulting from incomplete deuteration at approximately 7.26 ppm). The exact position of the absorption for water is strongly dependent upon water concentration in the sample and possible hydrogen bonding. The absorption for residual chloroform is relatively constant, provided no complexing or hydrogen-bonding species are present. In the presence of such complexant species, the absorption can shift downfield (to a few parts per million higher). I3 C NMR spectra were acquired with proton decoupling. Most of the spectra were obtained from the same samples prepared for 'H NMR spectra. For the less-soluble gaseous samples, the spectra were obtained with either chloroform-d or acetone-d6 used as the solvent. Solutions of gaseous compounds were prepared by first cooling 5 mL of the solvent (in a 10 mm quartz NMR tube) in an ice bath for 5 minutes. The gaseous compound was then bubbled into the solvent for 2 minutes, and the tube was sealed. Chemical shifts are reported in ppm with TMS used as an internal standard. As with 'H and I9 F spectra, expanded scale spectra are often presented of the more important complex peak multiplets. The reader should note the presence of very common impurity peaks on many of the I3C spectra. The main impurity is residual chloroform (from incomplete deuteration). These absorptions produce a characteristic and almost ubiquitous triplet at approximately 77 to 79 ppm. Known impurity peaks on any of the NMR spectra are indicated by an asterisk. The chromatographic retention measurements were performed with a packed column containing a 5 percent coating of a low-molecular-weight polymer of hexafluoropropylene epoxide on a graphitized carbon black. This material was described more fully in Chapter 1. Measurements of the net retention volume, V^1 (corrected to a column temperature of 0°C), of

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many of the more volatile materials were performed at four temperatures and were plotted as In(V^) against 1/T (where T is the thermodynamic temperature). The reader should note that this corrected net retention volume is the instrument-independent specific retention volume, Vg, with the mass of stationary phase, Ws, set equal to unity. Each measurement was performed five times to provide reliable mean values and statistics. These temperaturedependent data were then fitted with the best linear model (simple linear, logarithmic, power, or exponential) [15,16], Included with each fluid are the coefficients, the Pearson correlation coefficient of the fit, and the temperature range over which the fit was taken. Most of the data are represented very well (within the total combined experimental error of all measured parameters) with the simple linear model: log 10 (V°) = m/T + b

(2)

where m is the slope and b is the intercept. In a few instances, the power model was slightly better at accounting for all of the structure in the data and provides a more accurate representation of the measurements. The form of this model is: lo g | 0 2 (v) = n[log(l/T)] + c

(3)

where n is the slope and c is the intercept. To recover the V° value from this model, one must take the antilogarithm (that is, 10X) twice. In general, it is not good practice to extrapolate beyond the temperature range of the measurements that was in the correlation. We have found with these compounds, however, that in the absence of other measured data, we may extrapolate (with caution) to a temperature 50°C higher than the range stated. Under these circumstances, the prediction must be regarded as a coarse approximation. Such a procedure would not be valid if a phase change were known to occur; thus, extrapolation to lower values of temperature is discouraged.

REFERENCES 1. Lide, D.R., Ed., CRC Handbook of Chemistry and Physics, 75th ed., CRC Press, Boca Raton. FL, 1994. 2. Braker, W., Mossman, A.L., Matheson Gas Data Book, 5th ed., Matheson Gas Products, East Rutherford, NJ, 1971. 3. Perrin, D.D., Armarego, W.L.F., Perrin, D.R., Purification of Laboratory Chemicals, 2nd ed., Pergamon Press, Oxford, 1980. 4. Reid, R.C., Prausnitz, J.M., Poling, B.E., The Properties of Gases and Liquids, 4th ed., McGraw Hill, New York, 1987. 5. Thermophysical Properties of Refrigerants, ASHRAE (American Society of Heating, Refrigerating, and Air Conditioning Engineers), 237 pp, 1976. 6. Sedivec, V., Flek, J., Handbook of Analysis of Organic Solvents, John Wiley & Sons (Halsted Press), New York, 1975. 7. Vargaftik, N.B., Tables on the Thermophysical Properties of Liquids and Gases, 2nd ed., Hemisphere Publishing Co., Washington, DC, 1975. 8. Summers, D.B., The Chemistry Handbook, Willard Grant Press, Boston, 1970. 9. Bruno, T.J., Svoronos, P.D.N., CRC Handbook of Basic Tables for Chemical Analysis, CRC Press, Boca Raton, 1989. 10. Bruno, T.J., Hansen, B.N., Wood, M., Refractive indices of some alternative refrigerant fluids and products, ./. Res. Nat. Inst. Stand. Techno/.. (U.S.), 99(3), 263-266, 1994. 11. Bruno, T.J., Spectroscopic library for alternative refrigerant analysis, NIST Special Publication 794 (National Institute of Standards and Technology), 192pp., 1990. 12. Bruno, T.J., Strategy of chemical analysis of alternative refrigerants, NIST Technical Note 1340 (National Institute of Standards and Technology), 104pp., 1990.

64

CRC Handbook for the Identification and Analysis of Alternative Refrigerants 13. Bruno, T.J., Analytical protocol for alternative refrigerant analysis, Part 1: Spectroscopic Methods, ASHRAE Trans., 98(2), 204, 1992. 14. Bruno, T. J., Analytical protocol for alternative refrigerant analysis, Part 2: Separation Methods, ASHRAE Trans., 98(2), 210, 1992. 15. Bruno, T.J., Caciari, M, Retention of halocarbons on a hexafluoropropylene-epoxide modified graphitized carbon black: Part I —methane based compounds, /. Chromatogr. A, 672, 149-158, 1994. 16. Bruno, T.J., Caciari, M., Retention of halocarbons on a hexafluoropropylene-epoxide modified graphitized carbon black: Part II —ethane based compounds, /. Chromatogr. A, in press. 17. Bruno, T.J., Caciari, M., Retention of halocarbons on a hexafluoropyrolene-epoxide modified graphitized carbon black: Part III — ethene based compounds, /. Chromatogr. A, in press.

LIST OF ABBREVIATIONS AND SYMBOLS Note: See also Appendix 4. C.A.S. Chemical Abstract Service. CC Closed cup (for flash point determination). D Debye units. g Grams. 1 Liquid state. L Liters. LEL Lower Explosive Limit. NA Not available. NE Not established. OC Tagliabue open cup, sometimes listed as the Tag open cup (for flash point determination). PEL Permissible Exposure Level (OSHA). ppm Parts per million. (Note: 100 percent = 1,000,000 ppm) TLV Threshold Limit Value (ACGIH, see Appendix 4). UEL Upper Explosive Limit, vol/vol A ratio calculated on a volume/volume basis, mass/mass A ratio calculated on a mass/mass basis. * Indicates calculated (estimated) values of parameters, or known spectral effects caused by impurities.

65

Analytical Data for Alternative Refrigerants and Related Materials

11

fluorotrichloromethane

synonyms: trichlorofluoromethane; trichloromonofluoromethane; fluorochloroform; Freon 11. structure:

C.A.S. Registry Number: 75-69-4 Relative Molecular Mass: 137.368

F Cl — C — Cl I Cl

Normal Boiling Point: 23.77°C Melting Point: -110.5°C

Density/Specific Gravity: 1.487 g/mL (20°C)

Critical Temperature:

Refractive Index: 1.3849 (20°C)

190.8°C

1.464g/mL(30°C)

Critical Pressure: 4.32 MPa

Acentricity: 0.189

Critical Density: 0.554 g/mL

Dipole Moment: 0.45 D

Solubilities: Soluble in alcohols, ethers, carbon tetrachloride (and many other organic solvents); water solubility: 0.11 percent (wt/wt) at 20°C. **********#*****#********************************************************

Vapor Density: 4.74

PEL: NE

TLV: NE

FlashPoint: does not flash

UEL: NA

LEL: NA

Toxicology: Relatively low toxicity; high concentrations cause narcosis and anesthesia. Reactivities and Chemical Incompatibilities: Incompatible with Al, Ba, Na, Li (reacts violently, especially if metals are finely divided); may attack Mg and its alloys; thermal decomposition can produce HP, HC1, CO, CO2, phosgene.

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CRC Handbook for the Identification and Analysis of Alternative Refrigerants

Mass Spectrum:

fluorotrichloromethane

m/e

Abund.

m/e

31.00

2373632

35.00 4090880

37.00 1209344

47.00 1624576

49.00

490944

66.00 1259520

68.00

405056

82.00

311488

84.00

198656

101.00 5864448

103.00 3563520

105.00

556096

117.00

89328

119.00

Abund.

78432

m/e

Abund.

m/e

Abund.

Infrared Spectrum - Gas Phase

Analytical Data for Alternative Refrigerants and Related Materials

67

68

CRC Handbook for the Identification and Analysis of Alternative Refrigerants

uv-visible

Abs, max: 2.96

\, max: 232 nm

X, cut off: 365 nm

Analytical Data for Alternative Refrigerants and Related Materials

12

69

dichlorodifluoromethane

synonyms: difluorodichloromethane; Freon 12. structure:

C.A.S. Registry Number: 75-71-8 Relative Molecular Mass: 120.93

F I Cl — C — Cl F

Normal Boiling Point: -29.79°C Melting Point: -158°C

Density/Specific Gravity: 1.292 g/mL, C, 30°C 1.75 g/mL, J, -115°C

Critical Temperature: 111.8°C

Refractive Index: 1.285, C, 26.5°C

Critical Pressure: 4.14 MPa

Acentricity: 0.204

Critical Density: 0.558 g/mL

Dipole Moment: 0.51 D

Solubilities: Soluble in alcohols, ethers, benzene, carbon tetrachloride; water solubility: 0.028 percent (wt/wt) at 25°C. ************************************************************^

Vapor Density: 4.2

PEL: 1000 ppm

TLV: 1000 ppm

Flash Point: nonflammable gas

UEL: NA

LEL: NA

Toxicology: very low toxicity; can cause conjunctivitis, narcosis, and epinephrine sensitization of the heart in high concentrations; simple asphyxiant. Reactivities and Chemical Incompatibilities: can react violently with Al, Mg, Na, K, Zn, especially if finely divided; thermal decomposition can produce F2, F", C12, phosgene.

70

CRC Handbook for the Identification and Analysis of Alternative Refrigerants

Mass Spectrum:

dichlorodifluoromethane

m/e

Abund.

m/e

Abund.

m/e

Abund.

19.00

1781248

49.00 2118656

70.00

290304

101.00 6191104

31.00

6535680

50.00 6535680

85.00 6535680

103.00 3487232

35.00

6535680

66.00 4904960

87.00 6535680

105.00

569792

37.00

5992960

68.00 1543168

88.00

120.00

45472

47.00

5880320

259776

m/e

Abund.

Infrared Spectrum - Gas Phase

Analytical Data for Alternative Refrigerants and Related Materials

71

72

CRC Handbook for the Identification and Analysis of Alternative Refrigerants

uv-visible Abs, max: 0.62

X, max: 206 nm

X, cut off: 245 nm

73

Analytical Data for Alternative Refrigerants and Related Materials

13

chlorotrifluoromethane

synonyms: Freon-13; monochlorotrifluoromethane; trifluorochloromethane; trifluoromonochloromethane. structure:

C.A.S. Registry Number: 75-72-9 Relative Molecular Mass: 104.47

Cl

F

C

F

I F Normal Boiling Point: -81.4°C Melting Point: -18TC

Density/Specific Gravity: 4.394 g/L (25°C)

Critical Temperature: 28.8°C

Refractive Index: NA

Critical Pressure: 3.87 MPa

Acentricity: 0.163

Critical Density: 0.578 g/mL

Dipole Moment: 0.5 D

Solubilities: Somewhat soluble in carbon tetrachloride; water solubility: 0.009 percent (wt/wt). ***************************************************************

Vapor Density: 3.61

PEL: NE

Flash Point: does not flash

UEL: NA

TLV: NE LEL: NA

Toxicology: May cause temporary respiratory irritation and, in high concentrations, narcosis; simple asphyxiant. Reactivities and Chemical Incompatibilities: Highly stable; thermal decomposition can produce HF, HC1, CO, CO2, phosgene.

74

CRC Handbook for the Identification and Analysis of Alternative Refrigerants

Mass Spectrum:

chlorotrifluoromethane

m/e

Abund.

m/e

Abund.

35.00 37.00

m/e

Abund.

m/e

Abund.

131584

47.00

12910

69.00

771712

87.00

84160

42720

50.00

168832

85.00

231808

104.00

1621

Infrared Spectrum - Gas Phase

Analytical Data for Alternative Refrigerants and Related Materials

75

76

CRC Handbook for the Identification and Analysis of Alternative Refrigerants

uv-visible

Abs, max: 0.1 5

X, max: 198 nm

X, cut off: 220 nm

Gas chromatographic retention: m b r -20

= 1176.28 = -2.26 = 0.99981 to 40°C

77

Analytical Data for Alternative Refrigerants and Related Materials

14

tetrafluoromethane

synonyms: carbon tetrafluoride; perfluoromethane. structure:

C.A.S. Registry Number: 75-73-0 Relative Molecular Mass: 88.005 F

F

C

F

F

Normal Boiling Point: -128.0°C Melting Point: -184°C

Density/Specific Gravity: 3.034 g/mL (0°C) 1.96 g/mL(-184°C)

Critical Temperature: -45.5°C

Refractive Index: 0.122 mL/g (27°C)$

Critical Pressure: 3.74 MPa

Acentricity: 0.177

Critical Density: 0.64 g/mL

Dipole Moment: 0.0 D

Solubilities: Soluble in benzene, chloroform, somewhat soluble in carbon tetrachloride; water solubility: 0.0015 percent at 25°C. *************************************************************************

Vapor Density: 3.03

PEL: NE

TLV: NE

Flash Point: does not flash

UEL: NA

LEL: NA

Toxicology: Relatively low toxicity; showing no notable physiological effects at low concentrations; simple asphyxiant; breathing high concentrations can cause lightheadedness, giddiness, shortness of breath and possibly narcosis. Reactivities and Chemical Incompatibilities: Incompatible with aluminum, especially if finely divided; thermal decomposition can produce F".

$ This value is the specific refractivity, K, (or the Gladstone-Dale constant) defined as (n-1) = Kp, where n is the refractive index and p is the fluid density.

78

CRC Handbook for the Identification and Analysis of Alternative Refrigerants

Mass Spectrum:

m/e

Abund.

m/e

Abund.

m/e

19.00 31.00

Abund.

45968

32.00

20288

50.00

48264

28192

34.00

4234

69.00

429952

m/e 70.00

Abund. 5355

Infrared Spectrum - Gas Phase

Analytical Data for Alternative Refrigerants and Related Materials

79

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CRC Handbook for the Identification and Analysis of Alternative Refrigerants

uv-visible

Abs, max: 0.0186

X, max: 192 nm

X, cut off: 225 nm

Gas chromatographic retention: m b r -20

= = = to

860.50 -2.14 0.99919 40°C

81

Analytical Data for Alternative Refrigerants and Related Materials

21

dichlorofluoromethane

synonyms: dichloromonofluoromethane; fluorodichloromethane; monofluorodichloromethane. structure:

Cl

F I C

C.A.S. Registry Number: 75-43-4 t Relative Molecular Mass: 102.924 Cl

H

Normal Boiling Point: 8.9°C Melting Point: -135.2°C

Density/Specific Gravity: 1.354 g/mL (30°C) 1.405 g/mL(9°C)

Critical Temperature: 178.5°C

Refractive Index: 1.3724 (9°C)

Critical Pressure: 5.18 MPa

Acentricity: 0.210

Critical Density: 0.522 g/mL

Dipole Moment: 1.3 D

Solubilities: Soluble in alcohols, ethers, acetone, benzene, carbon tetrachloride, chloroform; water solubility: 0.16 percent (wt/wt) at 30°C; 0.055 percent (wt/wt) at 0°C. ****##**#*#******##***#*######*****************************^

Vapor Density: 3.82

PEL: 1000 ppm

TLV: 10 ppm

Flash Point: NA

UEL: NA

LEL: NA

Autoignition Temperature: 550°C Toxicology: Relatively low toxicity by inhalation, but may cause tremor and convulsions at higher concentrations or upon long term exposure; simple asphyxiant. Reactivities and Chemical Incompatibilities: Relatively unreactive at lower temperatures; at high temperatures, metals can catalyze breakdown; the reactivity toward metals under high temperature conditions is: silver > brass > bronze > aluminum > 1340 steel > copper > nickel > 18-8 stainless steels > inconel (which is the least reactive); some reactions may be faster in the presence of water. Incompatible with strong oxidants, magnesium, potassium, sodium, zinc; thermal decomposition can produce HC1, HF, CO, CO2, and phosgene. $ New registry number: 39289-28-6.

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CRC Handbook for the Identification and Analysis of Alternative Refrigerants

Mass Spectrum:

dichlorofluoromethane

m/e

Abund.

m/e

Abund.

m/e

31.00

1820672

37.00

32.00

1530880

35.00 36.00

Abund.

m/e

Abund.

705728

69.00 4157952

101.00

147840

47.00 1906176

84.00

153984

102.00

284864

2194432

48.00 1011712

85.00

438144

104.00

185152

234368

67.00 6517760

86.00

25912

Infrared Spectrum - Gas Phase

Analytical Data for Alternative Refrigerants and Related Materials

83

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CRC Handbook for the Identification and Analysis of Alternative Refrigerants

uv-visible

Abs, max: 0.52

X, max: 202 nm

\, cut off: 235 nm

Gas chromatographic retention: m b r 40

= 1518.77 = -2.36 = 0.99998 to 100°C

85

Analytical Data for Alternative Refrigerants and Related Materials

22

chlorodifluoromethane

synonyms: difluoromonochloromethane; monochlorodifluoromethane. structure:

C.A.S. Registry Number: 75-45-6 Relative Molecular Mass: 86.469

F H

C

Cl

F

Normal Boiling Point: -40.75°C Melting Point: -160°C

Density/Specific Gravity: 1.194 g/mL (25°C)

Critical Temperature: 96.15°C

Refractive Index: NA

Critical Pressure: 4.97 MPa

Acentricity: 0.221

Critical Density: 0.521 g/mL

Dipole Moment: 1.44 D

Solubilities: Soluble in ethers, acetone and chloroform; water solubility: 0.15 percent (wt/wt) at 30°C; 0.060 percent (wt/wt) at 0°C; will hydrolyze under alkaline conditions. ******************************************************************************

Vapor Density: 3.87

PEL: NE

Flash Point: does not flash

UEL: NA

TLV: 1000 ppm LEL: NA

Autoignition Temperature: 632°C Toxicology: Low toxicity; has no odor at concentrations below 20 percent (wt/wt); simple asphyxiant. Reactivities and Chemical Incompatibilities: Relatively stable; pyrolysis results in the formation of polytetrafluoroethylene (PTFE); will hydrolyze in water under alkaline conditions; incompatible with alkali and alkaline earth metals.

86

CRC Handbook for the Identification and Analysis of Alternative Refrigerants

Mass Spectrum:

chlorodifluoromethane

m/e

Abund.

m/e

Abund.

m/e

Abund.

m/e

Abund.

31.00

843840

38.00

16720

52.00

33824

69.00

148672

32.00

419584

50.00 281024

67.00

463808

86.00

19320

35.00

425280

51.00 3601920

Infrared Spectrum - Gas Phase

Analytical Data for Alternative Refrigerants and Related Materials

87

88

CRC Handbook for the Identification and Analysis of Alternative Refrigerants

uv-visible

Abs, max: 0.10

X, max: 194 nm

X, cut off: 220 nm

Gas chromatographic retention: m b r -20

= = = to

1256.10 -2.29 0.99986 40°C

89

Analytical Data for Alternative Refrigerants and Related Materials

23

trifluoromethane

synonyms: fluoroform; methane trifluoride. structure:

C.A.S. Registry Number: 75-46-7 Relative Molecular Mass: 70.01

F H

C

F

F

Normal Boiling Point: -82.15°C Melting Point: -163°C

Density/Specific Gravity: 1.52 g/mL (-100°C)

Critical Temperature: 25.83°C

Refractive Index: NA

Critical Pressure: 4.82 MPa

Acentricity: 0.260

Critical Density: 0.526 g/mL

Dipole Moment: 1.65 D

Solubilities: Soluble in alcohols, acetone, and benzene; water solubility: 0.10 percent (wt/wt) at 25°C.

Vapor Density: 2.4*

PEL: NE

TLV: NE

Flash Point: does not flash

UEL: NA

LEL: NA

Toxicology: Mildly irritating to respiratory system; narcotic at high concentrations; very low toxicity. Reactivities and Chemical Incompatibilities: Thermal decomposition can produce HF; very stable toward most materials, exceptions are N2O3 (above 175°C) and NOF (at or above 100°C).

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CRC Handbook for the Identification and Analysis of Alternative Refrigerants

Mass Spectrum:

t.ri f 111 nr nm pt.h a n

m/e

Ahund.

31.00

24816

32.00

23888

m/e

Abund.

50.00

5930

m/e 51.00

Abund. 47104

m/e 69.00

Abund. 9690

Infrared Spectrum - Gas Phase

Analytical Data for Alternative Refrigerants and Related Materials

91

92

CRC Handbook for the Identification and Analysis of A Iternative Refrigerants

uv-visible

Abs, max: 0.063, -0.005

\, max: 202 nm, 275 nm

X, cut off: 300 nm

Gas chromatographic retention: m b r -20

= = = to

948.39 -2.16 0.99995 40°C

93

Analytical Data for Alternative Refrigerants and Related Materials

32

difluoromethane

synonyms: methane difluoride; carbon fluoride hydride. structure:

H

F I C I F

C.A.S. Registry Number: 75-10-5 Relative Molecular Mass: 52.024 H

Normal Boiling Point: -51.75°C Melting Point: -136.8°C

Density/Specific Gravity: 0.909 g/mL (20°C)

Critical Temperature: 78.41°C

Refractive Index: 1.190, 8, (20°C)

Critical Pressure: 5.83 MPa

Acentricity: 0.271

Critical Density: 0.430 g/mL

Dipole Moment: 1.978 D

Solubilities: Soluble in alcohols, somewhat soluble in carbon tetrachloride; low water solubility.

Vapor Density: 1.8*

PEL: NE

TLV: NE

Flash Point: NA

UEL: 14.6%

LEL: NA

Toxicology: Detailed toxicology is not available; may cause irritation of mucous membranes; may cause nausea, twitching, narcosis. Reactivities and Chemical Incompatibilities: Thermal decomposition may produce HE.

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CRC Handbook for the Identification and Analysis of Alternative Refrigerants

Mass Spectrum:

difluoromethane

m/e

Abund.

m/e

Abund.

m/e

Abund.

19.00

15413

31.00

107992

33.00

359552

28.00

20176

32.00

45968

51.00

92288

m/e 52.00

Abund. 10069

Infrared Spectrum - Gas Phase

Analytical Data for Alternative Refrigerants and Related Materials

95

96

CR C Handbook for the Identification and Analysis of Alternative Refrigerants

uv-visible

Abs, max: 0.063

X, max: 200 nm

X, cut off: 240 nm

Gas chromatographic retention: n c r -20

= = = to

2.83 7.04 0.99932 40°C

97

Analytical Data for Alternative Refrigerants and Related Materials

40

chloromethane

synonyms: methyl chloride. structure: H

C.A.S. Registry Number: 74-87-3 Relative Molecular Mass: 50.49

H — C — Cl

I H Normal Boiling Point: -24.2°C Melting Point: -97.1°C

Density/Specific Gravity: 0.9159 (20/4°C)

Critical Temperature: 143.15°C

Refractive Index: 1.3389 (20°C)

Critical Pressure: 6.7 MPa

Acentricity: 0.153

Critical Density: 0.364 g/mL

Dipole Moment: 1.87 D

Solubilities: Soluble in alcohols, ethers, benzene, acetone, chloroform. ************************************************************************** Vapor Density: 1.78

PEL: 100 ppm

TLV: NE

Flash Point: 0) and (choicetemp) or

(max_coeff[1]temp) or (max_coeff[2]=l) and (ch