Dipole moments of some chlorocarbonates in solution

Citation preview

MANUSCRIPT THESES Unpublished th e se s subm itted fo r the m a s te r's and d o c to r 's ‘ degrees and d e p o site d in th e Louisiana S ta te U n iv ersity L ibrary a re a v a ila b le f o r in s p e c tio n . r ig h ts of th e a u th o r.

Use of any th e s is i s lim ite d by the

B ib lio g ra p h ic a l re fe re n c e s may be noted, b u t

passages may not be copied unless th e author has given perm ission. C re d it must be given in subsequent w ritte n or published work* A l i b r a r y which borrows t h is th e s is fo r use by i t s c lie n te le i s expected to make sure t h a t the borrower is aware of the above r e s tr ic tio n s * LOUISIANA STATE UNIVERSITY LIBRARY

119-a

D IPO LE MOMENTS OF SOME GHLOROCARBONATE8 IM SOLUTIOH

A D is s e rta tio n

S u b m itte d to th e G rad u ate F a c u lty o f th e L o u is ia n a S ta te U n iv e r s ity and A g r i c u l t u r a l an d M echanical C o lle g e in p a r t i a l f u l f i l l m e n t o f th e r e q u ir e m e n ts f o r th e d e g re e o f D o cto r o f P h ilo s o p h y in The D ep artm en t o f C h em istry

by R o b e rt Emerson Wood B . S . , Rhode I s l a n d S ta te C o lle g e , 1937 M* S*, L o u is ia n a S t a t e U n i v e r s i t y , 1939 J u n e , 1942

UMI Number: DP69229

AN rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion.

U M I' D issertation Publishing

UMI DP69229 Published by ProQuest LLC (2015). Copyright in the Dissertation held by the Author. Microform Edition © ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code

P ro Q u est ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106- 1346

E9C99 42

t h e au th or w ish e s t o e g r e s s h i s s in c e r e a p p r e c ia tio n t o B r. a* B* Gboppin* d ir e c t o r o f t h i s work* f o r con­ s id e r a b le h e lp f u l a d v ic e a ad a s s i s t a n c e *

He i s Indebted

to Br* and Mrs* fra n k h . P a d g ltt* Dr. E. 3* Amis* Dr* 0 . f . E ir b y , Mr* Edgar I*. Oompere, Mr* James W* B ogers and Mr* B. 8* S a r r e tt f o r t h e i r a s s i s t a n c e and s u g g e s tio n s

throughout th e co u rse o f t h i s study*

11 y > i,% V H 0 1 " w x t,.X

34 U f r i

TABLE Of OOHWKfS I* I n t r o d u c t i o n ....................... . .............................. . , . •

X

Review o f th e L i t e r a t u r e .............................................

3

IX .

I I I * E x p e rim e n ta l Work

...........................

.

8

1* P u r i f i c a t i o n o f M a t e r i a l s ..............................

8

2 . M easurem ent o f d i e l e c t r i c

C o n s ta n ts

. . . . . . . . .

........................

IE

. • •

1?

3 . M easurem ent o f D e n s i tie s an d

R e fra c tiv e I n d i c e s IV , V.

E x p e rim e n ta l R e s u lts

............................

19

D is c u s s io n o f R e s u lts

...............................

26

Summary

.......................................

33

V II .

B i b l i o g r a p h y ........................................................................

34

V III.

V i t a ..........................................................................................

46

V I.

ill

LIBf

or

fAMMB

X. P u r if ic a t io n o f M a te r ia ls • • • • • • • • • •

11

XI. P o la r iz a t io n s o f Benzene-GHLoroe&rbonate B in a r ie s a t 2 5 ° 0 . . . ...................................................

24

I I I . D ip o le Moments o f th e C hlorooarbonates a t 25°C.....................................................................................

ir

25

LIST OF PI0URSS 1 . D i e l e c t r i c C onstant

M easuring C a ll

IS

2 . W eighing B o t t l e ......................................... ....

16

3* P o la r is a t io n t i . C o n cen tra tio n f o r th e C h lorocarb on ates in Benzene S o lu tio n a t 2 S ° C . ...........................................................................................

22

4 . D ip o le Moments vs* Humber o f Carbon Atoms i n th e Hormal G hlorooarbonate

v

Chain

.....................

2?

A M tm O f The r e l a t i o n o f th e d i e l e c t r i c p r o p e r t ie s o f ch em ical compounds t o t h e i r m o lecu la r s tr u c tu r e i s one o f the more r e c e n t f i e l d s o f t h e o r e t ic a l c h e m istr y .

The i n v e s t ig a t io n

re p o r te d h ere d e a ls w ith a stu d y o f th e d ip o le moments o f s e v e r a l o h lo ro o a rb o n a tee in benzene s o lu t io n ,

th e gen eral

method u sed mas t h e b in a r y m ixtu re method o f W illia m s. A h eterod yn e b ea t ap paratu s and a d i e l e c t r i c con­

s t a n t m easuring c e l l have been c o n str u c te d and used f o r t h i s work.

The d ip o le moments o f m e th y l, e t h y l, n -p r o p y l,

n -b u ty l and n-amyl c h lo r o ca rb o n a te s have been measured a t 25°C. i n ben zen e s o lu t io n and found to b e , r e s p e c t iv e ly , 2 .4 2 , 2 .6 6 , 2 .6 8 , 2 .6 9 and 2 .7 2 Debye u n i t s .

For i-p r o p y l

and phenyl o h lo ro o a rb o n a tee th e v a lu e s a re 2 .7 7 and 2 .3 1 Debye u n i t s , r e s p e c t i v e l y , c l e a r l y in d ic a t in g th e change in p o la r it y o c c a sio n e d by the secondary and arom atic carbon lin k a g e s . The s t r a ig h t ch a in a lip h a t ic oh lorooarb on atee have been shown t o f i t th e a ccep ted t h e o r ie s o f d ip o le moments in homologous s e r i e s .

A c o n sta n t d ip o le moment f o r th e

h ig h e r members o f th e s t r a ig h t ch a in s e r i e s i s in d ic a t e d . Phenyl ch lo ro ca rb o n a te has been shown to p o s s e s s a mesomeric moment*

T h is moment i s o f th e same order o f

vl

m ag n ltu d e a e o t h e r v a lu e s r e p o r t e d I n t h e l i t e r a t u r e f o r m ost a r o m a tic com pounds. C om parison o f th e e x p e r im e n ta lly d e te rm in e d v a lu e o f th e d ip o le moment o f m eth y l o h lo ro o a rb o n a t© w ith c a l c u l a t e d v a lu e s f o r two p o s s i b l e m o le c u la r s t r u c t u r e s i n d i c a t e s two p l a u s i b l e h y p o th e s e s f o r th e m o le c u la r form o f lo w e r a l k y l e h lo ro c a rb o n a te *

I t I s s u g g e s te d

t h a t m eth y l e h lo r o c a r b o n a te e x i s t s e i t h e r i n two r e s o n a t i n g fo rm s o r t h a t i t e x i s t s e s s e n t i a l l y I n th e form f o r w h ich a h ig h e r d ip o le moment i s c a l c u l a t e d . The a p p a r e n tly anom alous r e s u l t s o f M izushim s and Kubo a r e r e a d i l y a c c o u n te d f o r i n th e l i g h t o f p r e v io u s r e s e a r c h by C h o p p in , F re & ian l and K irb y who have shown t h a t th e th e rm a l d e c o m p o sitio n te m p e ra tu re o f e t h y l e h lo r o c a r b o n a te i s w e ll below th e te m p e ra tu re a t w hich th e s e I n v e s t i g a t o r s w ere o p e r a t in g .

vii

w m om cno®

The s p e c i a l i z e d f i e l d o f t h e o r e t i c a l c h e m is try d e a l i n g w ith t h e p erm a n en t e l e c t r i c p o l a r i z a t i o n o f m o le c u le s d a t e s from th e i n t r o d u c t i o n o f th e d ip o le moment c o n c e p t by Debye i n 1912 ( 9 ) .

Through th e l a s t t h r e e decades#

t h i s f i e l d h a s p ro v id e d v a lu a b le I n fo r m a tio n r e g a r d in g m o le c u la r s t r u c t u r e . The g e n e r a l e x p e rim e n ta l m ethod o f a p p ro a c h f o r e v a l u a t i n g d i p o l e moments h a s b een to m easure th e d i e l e c t r i c c o n s ta n t.

T h is may be done e i t h e r i n th e

g a s p h a s e o r i n a d i l u t e s o l u t i o n o f th e p o l a r con­ s t i t u e n t i n a n o n - p o la r s o l v e n t .

The m ost d i f f i c u l t

e x p e rim e n ta l p ro b lem to b e overcom e i n work o f t h i s ty p e i s to s a t i s f a c t o r i l y and p r e c i s e l y d e te rm in e th e d i e l e c t r i c c o n s ta n t o f th e s u b s ta n c e whose d ip o le moment i s d e s i r e d . The aim s o f t h i s i n v e s t i g a t i o n have been to f u r t h e r in c r e a s e th e a v a i l a b l e d a t a on d ip o le moments and* i n p a rtic u la r#

to th ro w some l i g h t on th e m o le c u la r s t r u c t u r e

o f th e c h l o r o e a r b o n a te s .

These compound® have been o f

r e c e n t i n t e r e s t i n th e f i e l d o f r e a c t i o n k i n e t i c s (4# 6 # 29)* S p e c tro s c o p ic and d i e l e c t r i c s t u d i e s o f th e e h lo r o c a r b o n a te s seemed to be a l o g i c a l s te p i n b u ild in g up more e x p e rim e n ta l f a c t s to s u b s t a n t i a t e th e k i n e t i c p o s t u l a t e s w hich may be ad v a n ce d f o r th e m echanism o f e h lo ro c a r b o n a te d e c o m p o s itio n s .

1

2 f h l s I n v e s t ig a t io n l a a p r e lim in a r y s tu d y o f th e d l e l e c t r l o p r o p e r t ie s o f the more common o h lo r o o a r b o n a te e .

A s im ila r

stu d y I n th e s p e c tr o s c o p ic f i e l d h a s been made by S m ith ( 4 ? ) •

RFFXEW OF THE LITERATURE A q u a l i t a t i v e d i s t i n c t i o n betw een e l e c t r i c a l con­ d u c t o r s and e l e c t r i c a l i n s u l a t o r s 3ms b ee n r e c o g n is e d s in c e th e tim e o f F a ra d a y .

The f i r s t a tte m p t to d e s c r ib e

th e d i e l e c t r i c c o n s ta n t a® an ato m ic o r m o le c u la r p r o p e r ty i s fo u n d i n th e c l a s s i c a l th e o r y o f C la u s iu s and M o so tti ( 5 # 38)*

M olecule® w ere t r e a t e d a s c o n d u c tin g s p h e re s

tqr t h e s e a u t h o r s .

S u b seq u en t d ev elo p m en t o f t h e ato m ic

th e o r y l e d Debye ( 9 ) i n 1912 to in tr o d u c e th e p erm an en t d ip o le moment c o n c e p t and s a t i s f a c t o r i l y e x p la in th e te m p e r a tu r e e f f e c t on d i e l e c t r i c s *

The e s s e n t i a l

a s su m p tio n o f D ebye 40 th e o r y i® t h a t th e r e s u l t a n t c e n t e r o f t h e p o s i t i v e c h a r g e s in a m o le c u le 1 ® n o t a p r i o r i s p e c i a l l y c o i n c id e n t w ith th e r e s u l t a n t c e n t e r o f t h e n e g a tiv e c h a r g e s .

T h is f i r s t c l e a r p i c t u r e o f

p e rm a n e n tly p o l a r i s e d m o le c u le s i s now r e g a r d e d a s th e b e g in n in g o f modern d ip o le th e o r y .

An im m ediate con­

seq u en ce o f th e new th e o r y was th e e x p la n a tio n o f th e anom alous d is p e n s io n o r d e c re a s e o f th e d i e l e c t r i c c o n s ta n t w ith in c r e a s e i n fre q u e n c y f i r s t o b se rv e d by Drude ( 1 1 ) .

Debye (1 0 ) gave a q u a n t i t a t i v e d e s c r i p t i o n

o f t h i s e f f e c t f o r some o r g a n ic l i q u i d s . The m ost r a p id g ro w th o f th e d ip o le th e o ry h a s ta k e n p la c e w ith in th e l a s t two d e c a d e s .

3

Some d ip o le

4 moments hav e b e e s d e te rm in e d by p a s s in g a beam o f m o le c u le s th ro u g h a n I n te n s e non-hom ogeneoua a l e e t r i e f i e l d and m e a su rin g th e d e v i a t i o n o f th e beam from i t s s tr a ig h t co u rse .

K alim an and R e ic h e ( 2 8 ) , S te m ( 5 6 ) ,

Wrede ( ? 2 ) , a n d S sterm an n (1 4 ) have s u c c e s s f u l l y u se d th e m o le c u la r beam te c h n iq u e .

Most i n v e s t i g a t o r s ,

h o w ev er, h av e u s e d d i e l e c t r i c c o n s ta n t m easurem ents f o r d e te r m in in g d ip o le mom ents. D i e l e c t r i c c o n s t a n t s have been d e te rm in e d by m e a su rin g t h e e l e c t r i c f o r c e a c t i n g th ro u g h a d i e l e c t r i c o r by d e te r m in in g th e v e l o c i t y o f e le c tr o m a g n e tic waves th ro u g h a d i e l e c t r i c .

However, th e m ost w id e ly u se d

m ethod to d a y i s b a s e d on th e m easurem ent o f e l e c t r i c a l c a p a c ity .

Smyth an d h i s cc * w o rk e rs (6 4 ) have p e r f e c t e d

an e l e c t r o n tu b e W heatstone b r id g e s u i t a b l e f o r d i e l e c t r i c c o n s ta n t m e asu rem e n ts.

W alden, U lio h , and W erner (6 6 , 66)

and S tr a n a th a n ( 68 ) h a v e , p e r h a p s , been m ost s u c c e s s f u l w ith a re s o n a n c e m ethod o f c a p a c ity m easu rem en t.

The

h e te ro d y n e b e a t m ethod h a s come i n t o g e n e r a l u s e a s th e m ost r e l i a b l e means o f m e a su rin g e l e c t r i c a l c a p a c ity o f i n s u l a t o r s o f lo w d i e l e c t r i c c o n s t a n t .

Zahn (7 3 ) i n

1924 d e v e lo p e d a h e te ro d y n e b e a t c i r c u i t f o r m e a su rin g th e d i e l e c t r i c c o n s t a n t s o f g a s e s .

R e fin e m e n ts and

v a r i a t i o n s o f t h i s m ethod a r e i n g e n e r a l u s e to d a y . Berweg ( 2 2 ) , W illia m s ( 6 9 ) , S t u a r t ( 6 9 ) , S an g er and S t e i g e r ( 4 6 ) , and num erous o t h e r s have f u r t h e r im proved in s t r u m e n ta tio n i n th e h e te ro d y n e b e a t c i r c u i t s .

5 The d ip o le moment i s g e n e r a l l y c a l c u l a t e d from c a p a c ity measurements o f a v ap o r o r a b in a r y l i q u i d m ixture*

L&nge ( S I ) , W illia m s (70)* and E r r e r a (1 5 )

d e v e lo p e d th e b in a r y m ix tu re te c h n iq u e and i t h a s s in c e become th e m ost w id e ly u s e d e x p e rim e n ta l m ethod f o r d i p o le moment d e te r m in a tio n s *

The v a p o r p h a s e method

i s m ore a c c u r a t e , b u t e x p e rim e n ta l d i f f i c u l t i e s have l i m i t e d i t s u se*

Kuho