The action of selenious acid on alxyl ethers of phenols and the mechanism of the catalysed racemisation of α-phenylethyl bromide

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1151741

(5 9 0 5 1 7 4 )

BOYD..GU-- ACTION OF SE

ProQuest Number: 10148283

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2» foxB stloB e t iMxtermedUite aeleelrm eetepemAa I s (SQpftatlOB r M « tl« u i w ith eelw alim d lo x iâ *

• •

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• • • • •

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4» Oonpwrlwan o f M lw aitet diew id# w itt wnlghur d ico id fl mai t e l l w i i m d ie s id e • • • • •

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3» H oaotions w ith ##l«nitm iio z id * f ie ld in g MleoitBR o Aoticm o f mpwan# hydrohromlo a cid on (^)«£-ohlarolN«thjrdzt>l • • • • • • •

192

(o ) Aoticm e f bronlne on (* )-g-ehüerobcm tbydzyl hPonlé#192 (d) Attempted porepaomtlon o p t le e lly a o t lt e £ -o h lorob«n«h yd ryl te e n ld e

• • • • 139

C* Concentr a t io n end r e e lsta n o e o f M to rated edlntlom a o f h p d r o i^ bromide l a oartom tetra ^ ilcn rld e .

dppam n. 1 . d etlm atlon o f th e aarfeoe area e f powdered g la e e • • • 196 2 . Rate aqnatlcm fo r a o a ta ly sed raeam leatlen reaotlem

RRfüUaCJïS

• 198

143

•* 1

•

me. ACIION 07 SisXKlilOOiS A31S OH AlKITL JsilHiOie 07 flWKOLS

PAJtg 1. IMTROmiCTlUg

1 . She U»e o f « e le n lw D ioxide In Organlo OhnBlatnr.

whereaa m lp h o r d io x id e does n o t o x id is e o rg an ic c«npounds and te llu r iu m d io x id

i s v ery poor in t h i s r e s p e c t (1}«

i t has been known f o r a long tim e t h a t selenium d io x id e $ so* le n io u s a c id and s e l e n i t e s a re reduced by a wide v a r ie ty o f o rg a n ic oounda. I t m s not# however# t i l l 19)2 t h a t K iley c a r r ie d out th e f i r s t sy ste m a tic study o f th e o x id is in g pro* p a r t i e s o f selenium d io x id e and i t s a p p lic a tio n s to s y n th e tie o rg an ic c h ^ n istry # ( 2 ) . Selenium d io x id e i s now w idely used a s an o x id is in g and dehydrogenating agent# I t s u s e fu ln e s s l i e s i n i t s e p e o ifio a c tio n # At room o r B odprate te m p eratu res i t o x id is e s m ethyl o r m ethylene groups to th e co rresp o n d in g aldehydes o r k eto n es (a c id s a re r a r e l y formed ) # i f th e s e groups a re a c tiv a te i by an adjaocm t double bond# carb o n y l o r aldehyd

group# an arom atic nucleus# o r an

a d ja c e n t n itro g e n atom in h e te ro o y o lio compounds# When th e o x id a tio n i s c a r r ie d o u t in g l a c i a l a c e tic aoid o r a c e tic an* h y d rid e th e r e a c tio n u s u a lly proceéds only as f a r as th e

•

2

a lc o h o l mtage# Organio su lp h u r owipoimds oontm lnlng th e group •tiH a r e o x id ise d to d is u lp h id ^ s

S elenluri d io x id e can

a ls o a c t a s a d(^hydrogenating agont* (3# #)# In o x id a tio n s w ith selenium d io x id e , th e su b stan ce to be o x id ise d i s e i t h e r h eated w ith selenium d io x id e a lo n e , o r i n w a te r, d i l u t e o r g l a c i a l a c e tic a o id , d io x a n , a lc o h o l, o r a n o i^ e r i n d i f f e r e n t s o lv e n t t o farm a more o r l e s s homo* geneoue s o lu tio n . O onaentrated au lp h u rio aoid has a ls o been es^loyed a s th e medium. D uring th e o x id a titm th e selenium d l* oxide i s reduce

t o selenium which i s p r e c i p ita t e d and can be

reooverf3d. skmo ty p i c a l eximiples o f th e u se o f selenium d io x id e a re : (a ) S a tu ra te d compounds. The low er a lc o h o ls a re o x id ise d to aldhyd

( 5 ) . C e rta in aatu*

ra te d a lio y o lio alecholB r e a c t a t mioderate te m p e ra tu re s , e .g . b o m e o l and ia o b o m e o l both g iv e camphorquinone (6 ). (b) U n satu rated oosKpounds. Methyl and methylcme groups a d ja c e n t to th e doublo bond i n tr s a tu ra te d a l i p h a t i c , a l io y c li c and p o ly c y c llo , a s w e ll a s i n arcH&atlo compounds, a re g e n e ra lly o x id ise d to th e oozresponding aldehydes o r k eto n es w ith b u t l i t t l e ac id foxm ation. An a d ja c e n t t r i p l e bond a ls o a c t iv a t e s (7 k

• 3 -

Beg# a lk y la te d aroi&atlo hydrocarbons y ie ld aldehydes and a c id s ( 8 )9 an th ra cen e givos anthraqtilnone ( 9 )# e th y le n e y ie ld s g ly o x a l ( 1 0 )# oyclopentene g iv e s oyclooe n te n e ^ o l and oyolcne n te n e -d io l ( 1 1 )# and l*hoptyne» 3 * o l i s o b ta in # from Imheptyne ( 1 2 ) . (c ) Oonpounds c o n ta in in g th e group «CO. Selenium d io x id e i s p a r t i c u l a r l y u s e f u l f o r o x id is in g m ethyl and m ethylene groups a d ja c e n t to th e CO « group#» y ie ld in g k eto « ald hydes and d i« and t r i k e t o n e s . 3 .g . aceto n e y ie ld s m ethyl g ly o x al ( 2 )# aoetelclehyd

g iv e s

g ly o x a l ( 2 )# a c e ty l aceto n e g iv e s 2 %j)%4 * trlk e to p e n ta n e ( 1 3 )# and camphor g iv e s oamphorquinone (14 ) . (d) As o dehydsrogenating a g e n t. Compounds c o n ta in in g two (CH^O.O^H^)^Se(OH^ (CH^0*0^fi^)^Se(0H)^ — ^

♦ HgO

(0H^0.C^H^)^8e ♦ HgO ♦ [o ]

•

12

•

In o r t ^ r to t e a t t h l a h jp o th a a ia two eiqporirem ta ware porfocmed# l a th e f i r a t 0 d lem lay l aelaalam dihydroxlde i n a n is o le e o lu tlo a m e h eated a t 1 3 0

1 5 (f f o r 15 hoar## h a t o n ly some lO i aa#

o o n re rte d in to th e se le n id e » Aa th # r é a c tio n between s e le a lo a # M id and a n is o le i s c l e a r l y cosqplex and e l M s n ta l se le n itm i s in a l l p r o h a b ility li b e r a te d ( i t was i n f a s t found in th e pro« d u e ts from 5 o a t o f 1 0 experim ents ) a seoond experim ent was perfonR sd. T his showed t h a t d iw ils y l selenium d ih y d ro x id e d is s o lv e d in 50fi a o e tic aoid o csitaln in n in suspension f r e s h ly p r e o ip ita te d selenium and a ls o selenium dioxide# when h eated f o r 3 hoars#was alm ost o m p le te ly oom rerted in t o d ia n ia y l se* Iw nide * no d la n is y l selenium d ih ydroxid ^ was re so re re d e in t h i s r e a o tio n and in th e r é a c tio n s between s e le n io u s ao id and o th e r p h e n o lic e th e rs# th e selem id es formed were a l* ways accompanied by re d sem i* so lid b y -p ro d u cts o f an i n t r a c t a b l e n a tu r e . th e n h e a tin g was co n tin u ed f o r p e rio d s lo n g e r th a n 2 0 h o u rs a somewhat h ig h e r y ie ld o f s e le n id

was o b tain ed b u t th e

p roduct was so impure t h a t th e i s o l a t i o n o f th e s e le n id e beosM v a ry la b o r io u s .

3 . m e g tr a e ta r » o f Bi—

D la n is y l aelanl& e h as p re v io u s ly basn p rap arad hgr K onakall

•

13

^

(37) 1^0 obtf^ined i t by tho aotloa of soloniua moBOobloride (bOgClg) on «nifiolet th e taain prodoot o f the reaotion being d l m i o y l selenitim dlohIorlde« Al^iulat and Keleon (38) made th e s e le n id e by red u o in g d la n is y l s a le n im d ic h lo r id e (f^HNS eelenlnm o%yohlorlde and a n is o le ) w ith slno# birt both these a u th o rs le a v e th e p o s itio n of th e selenium atom undeterm ined#

th o u ^ Alqulet a i^ heleon assumed i t to ooc^upy th e para»i>oei* t l o n r e l a t i v e to th e m ethoryl*groups # I t h as now been estab­

lish ed t h a t d ia n is y l s e le n id e Is In fo o t di-g-methoxyphenyl s e le n id e . (a ) The method o f preparation o f Kunokell and o f Al jU ist Kelson and th e f a c t t h a t th e oompotznd forms a dibromide and . a dihydroxide show t h a t i t I s a s e le n id e . (b) In o rd e r to v e r if y t h a t th e selenium aton; i s a tta c h e d t o "Wtie bensene n u cleu s and n o t to th e carbon atoms i n th e m e tt03^1-groups# th e methoagrl-grottps vvere estim ate d by %9 ls e l * e m ethod. The a n a l y tic a l r e s u l t ooxresponda to two methoxyl* groups i n th e m olecule o f d ia n ia y l s e le n id r. (o) f in a lly # di-£-m ethoxyphenyl s e le n id e was o b tain ed by th e a c tio n o f potassium polyse>Ionide on d la s c tis o d £ - a n is id in e and proved to be id u t l c s l wit!i th e d la n is y l s e le n id e p rep ared from e e le n io is aoid and a n is o le . In an a tte m p t to p rep are di-o-m ethoxypheayl a e lm id e

• 14 •

.for oom rfirntlve p\t?rpcs»r? by th e a c tio n o f p o ta sA lw poXyoolen lâ e on d ia z o tis e

1

£-*anl!^liHne, di-o-m ethoxyphenyl d is e le n id e

was obtained»

4 . The A ction o f Solenloun Aoid on O ther H ien o lic ith e r e and Some ^ d eriv ativ es o f th e S elen id ee Pormed.

S elenid v^s were a ls o o b ta in e

by th e 4iOtion o f selen io tu i

a c id on phonetole^ o** and gydix?;et)io]Qrben%ene, 1* azkl oxynai h th a lo n e * and j>-*bro5ioanif^ole» o«dimethoK.rbens;ene gave a m ixture o f se le n id e and dlaolo** n ld

vdiioh wero s e p a ra te d by f r a c t i o n a l c r y s t a l l i s a t i o n from

alcohol» D iphenetyl s e le n id e has p re v io u sly been prepared by A lq u ia t and Kelson (38) and K unokell (37)# th e two di^m ethoxynaj^thyl s e ls n ld e s have been made b e fo re by ^ io h a e lie abd K unokell (59) by th e a c tio n o f selenium o x y o h lo rid e on th e a p p ro p ria te motliyl n ap h th y l eth er# A lq u le t and Kelson f a i l e d however to p re p a re a selenium d lo h lo rld e by th e a c tio n o f selenium oxyohlorld i on gybrom oanisole # S elen io u s aoid r e a c te

w ith pydimethoxybenzene and w ith

d ip h en y l e th e r to g iv e su b sta n c e s o f h ig h m e ltin g p oint# b u t aa i t was n o t found p o s s ib le to p u r if y them th ey were n o t f u r t h e r in v e s tig a te d #

• 15 -

oinofi, in th e cuae o f an iü o l'^, th e «olftiiiona mold a tta o k g th« bong «ne n u cleu s In th e parm** >o.nitlon r e l a t i v e to th e ffiethoxyl-grotjp, i t i s p>robr\tole th a t th e se le n id e o b ta in ed farcK p h en eto le l a d l-^ -e th o s rp h e n y l s e lo n ld e i %nd th o e e ob­ ta in e d from o - and

im ethoxybenaene a re b l3 - 3:4~ and

b i e - 2 ; 4*dlmethoxyphQnyl a e le n ld ^^ r e jtc a c tiv e ly . The ao len id e from ]>-bro!scaniaole m s t be e i t h e r d l - { 5 -*bromo-2 -r.«thoxrphanyl) s e le n id e o r d l - ( g-k&Tomo-S-methoxyphanyl ) nalanldo# In ord r to c h a r a c te r is e th e fielenideo o b ta in e d , th e folIi>wing d e r iv a tiv e s v/era p rep ared : d la n is y l seloniiim cUbroirdd

by th e a c tio n o f bromine on the o e le n ld e ;

d ia n is y l selenium d lh y d ro x id e , (a) by th e a o tlc n o f hydrogen i ro x ld e cn th e s e le n id e , and (b) by th e a c tio n o f aqueous sodium kydroxldB on th e dlbrom id . In a d d itio n th e correspond­ in g d e r iv a tiv e s o f d ip h e n e ty l se le n id e were p rerared # îhû s e le n id e o b tain ed from o-dimethoxybengene y ie ld e d a dihydroxid

on tro atm o n t w ith hydrogen peroxide b u t no s o lid

d lb ro n id o could bo pro'pare , In t h i s corm eotlon i t 1 s o f l a t o r e a t to n o te t h a t th e r e are many e&sefc c f d ia r y l s e le n id es f a l l i n g to give o r y s ta l lin o dlbrom id^s on -^ id itlo n o f brom ine, e.g» no dibroîsid s oculd bo p rap are t from ^-aethoxyphenyl phenyl s e le n id e and fror^ & -tc ly l p h ^ l so lm ild e ( 4 0 )# 2?he se le n id e o b ta in ed from m-dimethoxvbensene vm# n o t

a tta c k e d by hydrogen p ero x id e and tre a tm e n t w ith bromine r e -

m

16 •

in a oomg^lex r é a c tio n In v o lv in g n u c le a r bz-omination# Die c e le n id ^ obt^^iaed from g^brom oaniuole vms n o t a tta c k e d hy hydrogen p ero x id e and bromine caused nuule^ir m ib e titn tio a to g e th e r w ith bromine a d d itio n » g iv in g a b la ^ dibranoethoxv* phenyl seloniuffl dibrom ide» No d r l v a t i v e e o f th e s e le n id e s o b t ined frw ; 1* and 2 -m«^hc%ywphthalene could be prepared by tre a tm e n t w ith

e i t h e r bromine o r hydrogen peroxide#

- 17 -

A ll m#p#8 a re tBocorreoted • MloroaiiAlyaes a re by Dra# W aller and ^ ^ raaa# , Oxford • Die varlocta e th e r s were p u r if ie d by shaking i n e th e r e a l e o l r t io n w ith aqneoue sodium hydroxide# follow ed by d A stiU a * tio n # fXW# i n th e c a s e o f 2^m ethoxynaphthalwie # by r e o r y s ta l* lis a tio n # The se lm in m d io x id e m s resab lim ed im m ediately b e fo re u se and wee o b tain ed a s lo n g o o lo u rle s e h e e d le s .

1 . SelemlooB Aolâ and A nlaolo.

n w Hon» Interaction of AAhydroae

Dioxide aafl *nlaol«.

A a d x tn re o f aolonlwn d io x id e. (50 g#) and «oü.sol« (125 G») (2*5 mol*) warn m aintained a t 1 )0 - 150* and e tix re d meohanio a l ly f o r 2Q hrs«# b u t no re^w kion took place# (mly a v e ry f a i n t y e l l w o o lo n r developed end th e selenium d io x id e rem ained unchanged# A s im i la r n e g a tiv e r e s u l t mis o b tain ed when s e le n iM d io x id e suspended i n a n is o le and dioxan was îm ated under r e f lu x f o r 20 hrs#

A o tiaa o f Selenium D ioxide on A nisole in th e BWesenoe o f Added Water#

A m ix tu re o f selenium d ioxido (50 g#)# w ater (d#2

• 18 •

ml#0 1 mol#)# and a n ia o le (1 2 5 g## 2#5 m ol#) a a s hem tei i n an o U « b a th a t 130

150^ f o r 20 hra# H eaotion soon s a t in#

th e m ixture e ffa rv a a o e â and darkened # $ha r e s u l t i n g p ro d u ct $ #%ioh c o n s is te d o f a re d m obile upper la y e r and a dark*red v is c o u s low er la y e r# was tr e a te d w ith a c u r r e n t c f steam u n t i l a n is o le ceased t o come over# The d ark » re I semi«>8 o lid non«vo* l a t ü e re s id u e was e x tra c te d w ith eth er# and th e e th e r e a l e x tr a c t was shaken w ith c h a rc o a l and d rie d w ith sodium su lp h ate# Removal o f th e s o lv e n t l e f t a p a le orange so lid # (27 5# « 20$ o llc # on 8#0g use4)# vdiich a f t e r s e v e ra l c ry s t a l l ! n a tio n s from alc(A%ol y ie ld i d ia n le y l selem ide (di*£»methoxyidienyl se len id a} # o o l w l e s s g lis te n in g l e a f l e t s # (19 g . ) , n .p . 56.5 - 5«®. (ftm w l; 0 ,5 7 .1 » H ,5.(X . O ale. f o r C#57#2| h#4#3X)# A lq u ist and Relson (}8) reco rd ra#p# 54*^« Hie atjueous r e s id u e from th e e th e r e x tr a c tio n c o n ta in e d selenium dioxide#and i n 5 ex p e rim m ts c u t o f 10 sm all amosnte o f b lack selenium (0#1 • 0#5 g#)# The s e lm iu n d io x id e was p r e c i p i t a t e i a s red selenium hy p a s s in g su li^ m r d io x id e in to th e aqueous re s id u e a f t e r a d d itio n o f concent ta ra te i h y d ro c h lo ric acid# The selenium w is co n v erted in to i t s b la ck m o d ifio a tio n on h e a tin g a t 90 • 100^#

a » I n f l uence o f Added w ater m th e r i e l d o f D ia n ia y l 3elepide# Selenium d ic x id

(22#2 g#) and a n is o le (43#2 g## 2 mol#)

- X9 •

were h e a te

w ith v a ry in g amounts o f w *ter a t 130 • 150® f o r

2 0 hre« %Q o m d e e e le n ld

o b ta in ed from th e e th e r e a l e x tr a o t

waa d r i e i to o o n s ta n t w eight In a vammm d ealo o eto r# The r e a u l t s a re s u m a rls e d in th e ta b le below#

Water added ml# m ol. 0

0

f ie ld o f d ia n ia y l a e le n ld e 8.

%

0.4

0 .7

1 .0

1 .7

0.Ü6

0.014

3 .6

1 .0

11.5

19.7

1 0 .0

2.W

3 .1

5 .3

When th e a lx tn r e vmn heated f o r lo n g e r jje rio d s o f tim e th e r e w e o b ta in e d more d ia n le y l a e le n ld e , b u t th e prodoot was l e s s pmm. Thus, selenium d io x id e (22.2 g # ), w ater (3#6 m l., 1 m o le), and a n is o le (4 3 .2 g . , 2 m ol.) h e a te t a t IJO • I 5 0 ® f o r 4 0 h r e . a ffo rd d 25 g . (3991 o f om de d ia n le y l s e l m i d e , which had t o be fre e d from o o lo n re ■ »«sl-so^ ld im p u r itie s by sp re a d in g on a porous p la te and many subsequent c z y e t a l l i s s tlo n s from a lc o h o l (8 - 1 0 tim e s ) . 16 g . ( 2 7 %) o f pure s e le n id f ware o b ta in e d .

B is n ls y l selegiim d lb ro m id e.

a s o lu tio n o f bromine

(3 g .)

I n oarbon d is u lp h id e (25 m l.) was poured I n to a s o lu tio n o f d ia n le y l s e le n ld e (1 g .) In carbon d is o lp h id e (25 m l .) . A lm s t

• 20 •

Imaa

d ia n ia y l aelanlw n dibrouilde aap aratad i n

ra d p ris m a tic rods* M#p# l i d • 120^ (dscomp. )* y ie ld alm ost q u a n t ita t iv e . (Pound: C * y /.0 | H ,3 .u ; 3^,35#j# C alo. f o r ^ 1 4 ^ 4 ^ 2 ^ 2 ^ * C*37#1| H *]).l; Br*36.6; ) . l^k q u ist and Belscm (30) g iv e m .p. 125^. llilm oomj>ound i s hl^dily s u s c e p tib le to m o istu re and a t t œ p t s t c r e c r y e t a l l l s o i t re s u lte d in i t s p a r t i a l oonveroion to th e oorrenponding seleniuin d ih y d rcz id . I t i s th e re f o r e bont prepared in d i l u t e s o lu tio n as givon above.

D ia n ia y l eelenium d ih y tiro z ld e .

(a) D ia n ia y l aelenlisn d l*

bromide (0 .7 3 &#) was t r i t u r a t e d vdLth aqueoua «mdium hydroxide (20 m l.* 3K). Ih e m a te ria l became : asty * l o s t c o lo u r and soon s e t h a rd . The r e s u l t i n g d ia n le y l se le n iim d ih y d rcx id o

sepa«

r a te d from a lc o h o l o r bensene in o o lo u rle s e needles* m .p. 1 4 tf # (Pound: C*51*6| H*4#C. C^^lo. f o r

0*51$4; H*4#%)#

A lq u ist and Nelson (38) give m .p. 134®« (b)

D ia n le y l s e le n id a (3 g . ) n as tr itm r a te d e i t h hydrog

X>erozide (35 ml.* 90A 00 v o le .* o a. 3 d )* Hhben a v ig o ro u s exotherm ic r e a c tio n s e t i n . The r e s u l t i n g d ia n le y l selenium dihydroxide (y ie ld nlm oet q u a n tita tiv e ) * a f t e r o r y s t a l l i e a t i o n from alcohol* had m .p. 14B^* alone* o r mlxe f w ith th e compound p ro p aro l in ( a ) . This compound l a n o t changed by h e a tin g a t 220^ f o r 10 aim#

- 21 -

A ttem ete# K tic tlo n between PiaoU url saU ntoB S lh rd ro x ia » and jin lo o l# .

D ia a la y l selenliam d ih y d ro x id a (0#5 6# ) and a n is o le

(r m l#) wexe h eated a t ly o • 150^ t o r 10 hre## th e red roH O tloa m ixture was tr e a te d w ith steam u r t i l no more a n is o le oame over# The n o a * v o la tile re e ld u e was o x tr a c te

w ith e t h e r , on removal

o f th e so lv e n t th e r e was ob tain ed d ia n le y l s o le n id e ( 0#05 &#), i d e n tif ie d by &#p# cmd mixed a#p# The e th e r* in s o lu b le re s id u e s o l i d i f i e d t o a o o lo u rle s e s o lid (0#4 s # ) , vdilch proved to be d ia n ia y l selenium d ih y d ro x id e , a ls o i d m t i f i e d by m#p# end mixed m#p# The e x p e r ip m t was re p e a te d u s in g Idis same q u a n tit i e s w ith th e a d d itio n o f a drop o f w ater# Only a v a ry f a i n t pink c o lo u r d v e lo p a d , no d ia n ia y l s e le n ld e was o b ta in e d , and alm ost a l l th e selenium dih y d ro x id e (C#45 &#, 30 O was recovered#

auMtlop Txatwwn Piaailgyl Selenium Dügarortdo. Selonltc and iSLeaental ^lenium#

An aqueous acetic acid solu tion o f

selenium dioxide oontainlng in suspension selenium vKis pre­ pared as follows# t>0 lenlusa dioxide (U#5 g# ) was suspezidsd in s mixture o f g la c ia l a cetic acid (1 ml#) and water (12 ml#}# nulphur dioxide w^ta passed into the mixture for 2 m in., there was a red proolpltate o f selenium but some selenium dioxide reniained# A further 0#2 g# of Roloniten dloxldo was then added# A small rortion of the mixture was heatei nearly be b o ilin g , filte r e d from selenium and the f ilt r a t e toated for sulphur dioxide by addiné:> fin aqueous solution of selenium dioxide#

-

Xhere ncis no r e

co l ur*

2y

#

th e

bsence c f s\ilplxur dioxide

in th e irix^iire #

Dianleyl eelenlnm dihydroxlde (0,5 g, ) mm g&admd to the mixture and the liqtiid was boiled im der reflwx for 5 hra# Aftar lo sr d r , the red o o lw r h d dlear reared and

oelenlem

hod settled to the bottom as a bl^ioh powder. The mlxttire was fllteitou hot fnwQ the precipitated selenltm* the selenium waa maehed with a l i t t l e hot alochol^ and the combined f ilt r a t e and Tfaahlngs were allow# I to c o o l. There separated oolcixrleaa p lates (0,22 B»)$

- 52®, raisml a fter one c r y s t a lli­

sation from alcohol to 5$ - 5Ï®* alono or mixed with dianiayl solenide, A farther 0,1 g , of dianiayl selenlde vma obtained on oonoantrating the f i l t r a t e , Ko dianiayl aele%d.%m dihydrozlde was reocvered,

.iattoation of the Wthoxvl Orovios in Dianiayl S^ilenide, miorcanalyses for methoxyl gave oon slsten tly low r e s u lts , (found: OCH.^,8,05,7,07#

requires 0CHj,21,2^), I t

was decided to oarxy out a modifie : Z eisel d termination on a maoro-scale. The apparatus used i s a modified form o f that given by Clarke (41) (See diagram next page). Carbon d io x id , from a o y lln d r vr a passed t h r o n g a sim ple n:erotiry p re s -u ro -re g u la tin g d ev ice and a wash-bottle c o n ta in in g c o n c e n tra te

s u lp h u ric acid in to a 50 m l, oonteal

Aa

2 1

CO.

• 24 •

ccntaiuin^ b nOL# of a mixture of aqxieouo hydrlodic aold and a cetic anhydrido# Prom there the gas passed throiigh the bent side-arm A, which contaiin^d î l i t t l e of the into the ICO ml# deccanpositlon flask B. Into B

mixture» been p laced

an accurately weighed amount (oa# o#> g# ) o f d ia n isy l s o le n id e together with a mixture of hydriodic acid (b#p# 126 - 127®» 25 ml#) and acetic anhydride (15 ml#)» the la tt e r in order to f a c ilit a t e decomposition# B was b e lle

gently over a Bnnaen

burner and the flow of water in the oondonsor jacket 0 was so adjusted that the vai ours passed over at K at 20 - 25®» th is was read on the thermomater I)# Prom J£ the vapours passed throuidi two 25 ml# absorption fla sk s In se ries which were maintained at 45 ~ 50® in a waterbath# Ths f ir s t fla sk contained a l i t t l e red phosphorus suspend­ ed in m tc r to absorb any froo iodine»

ücetio acid or hydrogen

iodide that had escaped condensation» and the (fécond fla sk contained an amQthoxyphenyl selenlde#

0CH^,21#2%?#

The f o i l wing Rf^thod o f pre­

paration w s adopted from Leloeator^s preparation of diphenyl selenido (42)# t'owder^id selenium (32 g . ) and powdered potassium hydroxide ( (48 g# ) were ground together and heated at 140 - 150® for 10 zain#, when a thick red liquid was f orme i vdiioh was poured on ic e (60 g .) I a red solution of potassium polysolenide resnltadi

• 26 •

]> -an isid in o h y d ro c h lo rid e (31«3 m ixture o f h y d ro c h lo rio a c id (31 ml#^

d is s o lv e d i n a and w ater (100 ml#)

d i a z o t l s e l ^vlth a s o lu tio n o f sodium n i t r i t e (13#8 g#) I n w ater (50 ml# ) below 5^# The r e s u l t i n g d ia s o - e o lu tio n was mm i n to th e loe«*eold potaaeium p o ly s e ls n id e so lu tio n # h e a t was evclved and a th i c k re " o i l sep arated # The s u p e rn a ta n t liq u id m s d roantedm^ h e a te d to b o ilin g fmd -xTurs l back on th e o il# The o d d m ixture was e x tra c te d vfith o th e r (300 ml#)# th e e th e r e a l e x t r a c t d rie d w ith sodium su lp h a te and th e s o lv e n t re ^ moved# The h r ig h t^ r e i a e » i« s o lid re s id u e w&s disfrolved in aleo h o l# a m ix tu re o f y ellow and red o ry sta ls (9 g#) separated on cooling# The m ix tu re was e x tra c te d wl*^ b o ilin g a lc o h o l (50 m l.)# p a le yellow p l a t e s (2#5 g.# bm5%) s e p a r a ta ! on oooJiing# Hepeated o r y s t a l l i e a t i o n s from a lc o h o l gave c o lo u r* l e s s l e a f l e t s o f di*£*ffiethoxyrhenyl se le n ld e # m.p# $6 - 57®» alone# o r when mixed /?ith th e d ia n is y l a e le n ld e p rep ared above#

Di*o*m ethoxm henvl d is e le n id o .

In an a tte m p t to p re p a re

d 1 *o*methoxypheny 1 s e le n id ) f o r purposes o f com%)arisen# th e above p re p a ra tio n was ro p o a to i# u sin g th e same q u a n titie s # b u t w ith o*etniaidine i n p la c e o f £ * an io id in e# Prom th e e th e r e a l s o lu tio n a rod o i l vns o b tain ed vdiloh was dian o lv ed In h o t a l* c o h o l. On cooling# th e s o lu tio n d ep o sited di*o*methoxyuhenyjl d ls e lo n ld o . (6#5 g.# 17.5 )# p a le yellow needles# m .p. 83 * 84®< (^ound: C #44.9| H#3#7.

C #45.2| H#3#8%).

- n

•

ce BeleiiloiiH Aold

i ) l A t h o x T D h enyl g^lenide#

A mixture ot'

dioxide

(20 Se)» wat^^r (3e2 nie» 1 mole )» and phenotole (515 nie» 2e2 molj]

was heated at 120 - 140® for :.’0 hroe Thm product, a fter treat* imnt vdth steam r t i l no more phonetole d ia tlllo d over» s o li*

d lfled to a red mass (20 g»» 'i5'^)§ which was repeatedly re* cxystalllsod from alcoliol (charcoale) Dl^jjpethoxyphanyl so le nldo

obtainod In oolonr le s s needles (11 g# » IT:')» mep#

61 - 02*^, (Xitotmd: C ,6ü.j; H ,5.6|

Omlc. for

i^»bO*l| H»5e7; 0C^yiç»2Bel-) The ethcxyi vmn osti* matad as tiesorlbod abovee A lcjnist and itolson (iB> g iv e ciePe t>0 * 62® e

Di*p*Qthoxynhonyl selenium dlbropAdOe

Iho sa lo n îd û (0*4 ge)

In chloroform (3 mle ) was treated with bromine (Oe5 n le ) On staïKilng» th e solution deposited di-£*Gthoxyphonyl selenlma dibrotnidrj in bright re i p lates (0.4 ge)» mepe 115^ (deoOTspe ) Alqnist >rd hoIson (3^) give n.pe 117®e

i iTr-othoxynhemrl selenium dlhydroxlde#

(a) 'fhe dibromlde

(Ue7 f:e) was tr itu r a te » with aqneoos sod^nm hydroxide (15 ml#» 3N)# The substance gradually lo s t colour» became pasty end f i n a l l y sat bird, x fter drying In air fo r 6 hra# I t formed a

rvhite i>oyvd r» m.p# oa#l4 0®# After several reoryrtalltaationa frwi alcohol i t w b obtained in colourless plat##» m#p# 172 *

- 28 «

W**. (Founa.- 0,54.4; H ,5.4. Cale, for

0 ,5 4 .1 ;

H,5.7' ). A lnrlst ar.d Kolnon (38? give m.r. 146 » 1a6®. (b) Dl-g-@ tboxyphenyl s e le n ld e (1 g .) t r i t u r a t e d w ith faydrogon p ero x id e (10 ml#* o a # 30 ) y ie ld e d a White powder* K#p#ca# 140^ a f t e r a i r - d j y i n g , ra la e d to 172 - 173® by cry* s t a l l i s a t i o n from alco h o l* e i t h e r alone o r ?dien mixed w ith hhe compound prepared in (a)# f ie ld alm ost q u a n t ita t iv e #

Ic -geltiilQna Aold and o^jmethoxyhengene#

MayJtL4rdinethoiarphoii7l aelezdd^ jmd Bjs-3 ;4-dimetho%rW%«a%l diaelenide#

A mixttcro of seleniiim dioxide (10 g# )* w ater

(1#6 ml#* 1 mol#)* and o-dimethoxyhonKene (25 g#* 2#1 mol#)

was maintained at 130 - 150® for 20 hrs# The resp itin g dark red secii-nolid wan treated nlth steam and extracted with e th e r as df scribe^l above# (ki removal of the solvent there wae ob­ tained a pink solid which proved to ba a mixture of s e le n ld e and diaelenido# These two products were separated by fr e o tio a e l c r y sta llisa tio n fiom aqueous alcohol# a s mere soluble b lc -3 :4-djmo1Ao%ybhenyl

(1#5 g##

4*7^) o ry sta llised in colourless needles* m#p# I d m. 102#5®# (Found: C ,54#l| H*5#2#

r e i u i r e s C*54#4> H*5#W).

-

29

-

Iho le a s so lu b le b l s - 3 : 4-dlB ethoxyohenyl f tls e le n ld e . (12.9 c . , 6 6 ') s e p a ra te ' frc® aloo%o; In an al] p ris m s , m .p. 169 - 170®. (Found : C,44.3{ H ,4 .0 .

re q u ira o 0 ,4 4 .5 ;

K ,4 .2 ^ ).

Bl8«3;4>dlgi«thoxyT)hen.Tl selenium d lh i'd ro z ld e was o b tain ed i s alm ost q u a n tita tiv e y ie ld when 1*e a e le n ld e (0 .4 g .) waa t r i t u r a t e d »-»ith hydrogen p ero x id e (30 m l., o a . 3 0 ) . I t se­ p a ra te d from a lc o h o l in o o lo u rle s s p l a t e s , m .p. 17o - 172®. (Found: 0 ,4 9 .7 j H ,4 .8 . CigBgQÜgSe r e q u ir e s 0 ,4 9 .6 1 H ,5«2ÿ). Areatmmnt o f th e s e le n ld e w ith bromine r e s u lte d i n th e fo rm atio n o f a brown o i l from which no o r y s t a l l l n e m a te ria l could be 1e c la te d ,

it-S ^ b h io M » Acid and m-Dimethoxvbeozene.

: 4-dim ethoxyphenyl s e le n ld e .

A m ixture o f s e le n iw i

d io x id e (30 g . ) , w ater (4 .8 m l., 1 m o l.), and ^ d lm o th o x y bensene (75 m l., 2.2 m o l.) was h eated a t 120 - 140® f o r 26 9

hro« A fte r steam c ^ ic t lll a tl o n and e th e r e x tr a c tio n a p in k flolld (25 £j#t 26%) was o b ta in ed « which ^ a f t e r re p e a te d cry» B ta lli a a ti o n s from a lc o h o l (c h a ro o a l), y ie ld d bie»2rA»dim eA» oxypheny l s e le n ld e > sm all o d o u r l e s s p l a t e s , m#p, 108 » 110®# 0 ,5 4 .6 ; H ,5 .2 .

r e q u ir e s 0 ,5 4 .4 ; H ,5 .W ).

• 30 •

n

no action on the aelenlde#

Bromine does not combine with the selenlde d ir e c tly to give an addition oompcimd# When a soln ticn of the aelenlde in oarbon disulphide la treated with bromine there i s a oc* pious ev o lu tim of hydrogen bromide but no ooloured addition oer.potind could be isolated#

5 . S alen lo n s Aold and l^ m e th o x y n a n h th ^ m iu

Dl~ (l-methoxynanhthyl ) selen ld e >

A mixtntre of selenium

d io x id e (20 g . )$ wAter (3#2 ml## 1 mol#)# and l-m «thoxy-

naphthalene (64 ml## 2#2 mol#) was heated at 140 • 150® for 20 hrs# The resu ltin g dark brown o il was t r e a t #

wildi steam

to remove u n reao ted ether and the water layer decanted from tW viscous non-volatile residue# On adding a drop of other and scratching# the o i l solidifier^ to a brown powder (20 g## 28%)# which on r e c r y sta llisa tio n froi^ alcohol yielded cli-(l-methomy** naphthyl) selenlde# yellow rods# a#p# 137 - 138®# (fouad: G#67#4| H#4#6# Calo# for GggH^^OgUe; C#67#2; H#4#6%)# Kiohaells and Xunckell (39) give m#p# 138®# Hydrogen peroxide did not react

the selenlde# bromiae

produced brown o i l s Which could not he Induced to so lid ify#

-

6

.

31

-

SBlanioos Aold aaft a-ttothoaàm aphthalwie»

P l»(g»—th o x y a n h th y l) a e lM ld e .

A m lztv ra o f aolamlum

d lo x ld o (1 0 g . ), m *tor ( 1 ,6 m l., 1 m o l.), and @-methoxy»nxqA'UialoBo (35 g , , 2 ,2 m o l,) «mo heated a t 1 |0 - 150^ f o r 12 h r s , n ie r e s u l t l a g d e r k - r e

gum «eta tr e a te d « d th ateam u n t i l no mere

2-m othoxynaphthaleno oame o v e r. On s ta n d in g , th e n o n - v o la tile resid u e s o l i d i f i e d to a hard re d t a r , Bepeated o x y a ta lU a a tlo n s f î t » aoetohe-aloW iol y ie ld e d d i - ( 2-m ethoxynapbthyl) a e le n ld e , (6 g , , 1 7 1 ), o o lo u r le ss n e e d le s, m,p, 163°* (Pound; 0 ,6 6 ,9 ; H ,4,9* O slo ,fo r H ,2 .7 |

BisH llbroaoM athoaynhaayl aaleMtim dibrom ide»

A s o lu tio n o f

th e s e le n ld e (0# ! g«) in oblorotoTm (5 m l. ) was tr e a te d w ith a drop o f brcm lno. There were fumes o f hjrdrogen bromide and la rg o red n e e d le s o f b lo rd lb rm o m e th o w rh e w l selenium dibrom W a m .p. 123 • 124® (deooB^?.) se p a ra te d on s ta n d in g , (found: ftr*6 1.2. ^

re c iu ire s Br*o2.3 ') •

The bromine d ireo tly attached to the selenium a tw a s dibromide was estimated by tritu ra tin g the biibromomethoign* phenyl selenium dibzwilde with standard sodium hydroxide so* lu tlon (0.2K)* f ilt e r in g tho oolourless hydrolysis produot and oatiiGating tho excess of sodium hydroxide by titr a tio n with standard hydrochloric aoid. (Pound: Br «s dibromide, 1 8 .4 ,1 3 .2 . Calo. B r, 2 ü .^ X .

6. io le n ic u a Aold and gpliim ethoxybenseaot b e le n io u s Aoid and Diohanyl zither.

A m ixture o f solenlvJir. d io x id e ,

and jv-dlmethoxybea*

îîene y ie ld e d a p a l a yellow $ o lid , r.%^. 275 - 300^, which was inmolubl:! in

11 th ? UMunl solvent:? »md

th o r^ fo re n o t

•

33

1a

«

fa r th e r H w eetig a ted . #l%h

o M a iM d .

ethwr • plmlk lirtracrtaUU

m m

»

34

•

TH,. yjÆHAJfliSM Of ïAb CftTALlfSta) HAOîiilSA'flOK Of Ig# aa oompAred ^vith BTg + 2H1 -----> 2HBr 4 1 ^ .

farther, the butyryl Hrpobromlte oo prepared combined with ovclohexene to give 2-broEccyolohexyl butyrate: % Q

CH

HgO

CH *

HgC CH.OOO.Pr H r .O U C te

'o
phenylethyl brom ide, oarbon d io x id e and two Io n s fA liA oomblne t o re g e n e ra te one m oleoale

-

58

-

o f a(rp)t«fl7 lp rop ioiiT l hypobronlt o ; ( 1) •

B • yü-*B r

H

OHaiMe.COO-SBr ♦ Ko-0-ÎC^ * -Û 4 CHîhBo.CüO A" 0

+ a r - è - î'^ * CO, Fh -

follow W by OBABo.OOO" + Br* — ^ CHFhKe.COOBr (% o oymbcl

-û-^

o ia n lf le a im ro ro lo n . )

I t i s pooalM.o

ao lo o Q lar b ro ain o may rww)t by a a l i i l a r n eo h sn lsn (11) to y lo ld o ^ p h eo y lo th y l to o a ld s , earbqn d lo x ld o , and Iona id tlsh roooKblno to ro g o n o ra te bronlB o; ( I I ) B r-:»r follow ed by

♦ CHfhMo-jcoo-jar -Cu^ Br“

♦

tr “

* Br-OHmKo + co + Br*

Br* — ÿ Br

F in a lly , a sm all oonoentratl< m o f brcHBliM c a tio n s m«v bo o it b o r mot up by r e a o tlo n s (1) and (1 1 ), oa may o z l a t I n o q u lllte lu m w ith CBPtiKscOOORr o r w ith B r^, and ra a o tlo n Bay th e n proeood by e q u a tio n (1 1 1 ), In oAloh ohidienylothyl baronldo mad oarbon d lo x ld o a re fonned and b ro n lao o a tlo n I s ro g o n o rato d i

(I I I )

Br* + CHntKo-jcoo-jBr

Br-CHEhKa * 00, + Br*.

In oaoh o f th o s e r= o tlo n s o ^ p h etrrlo th y l bromldo la formed by an e le o tz t^ p h lllo b ln o lo c u la r a u b s t l t u t l w (8 ^ 2 ), sh lo h In v o lv es lnv«atdLon o f c fm fig n m tlo n (Buddies and In g o ld , 4 8 ) . H eaotlon prooeeda t h r o n g th e t r a n s i t i o n complex

SB*

Ç .....COOIbr* îh

-

39

-

In which tho Br>C bond fo n ts s lm lta n e o a s ly wl%t tho rolnm stlon o f tho C»OOOBr bond, and along th e a x is o f tdM la t t o r , but s t tho op p osite faoo o f tho oarbon atosi. n io p a r tia l raow olsatlon o f tho r o s u ltln g o^phomylothyl bronldo I s thought t o bo duo to tho a o tlo n o f hrsntao and sllT o r bromide o s th o o p tic a lly pure «^phosylothyl bronldo during tho period e la p sin g botuoon i t s fu m a tlo n and tho end o f tho oxporlnant; and I t was found In a sep arate osporlaoH t ‘t iia t o p tlo a lly aetlT o oHlAtonylethyl bronldo does In f a s t tmd rgo r a e o n lsa tlo a In tho prosonoo o f bronlne and s ilv e r bronldo# I t I s shown la t e r th a t th a t tho r a o o n ls a tlw o f e^phonjrl* e th y l b ro n ld ; l a oarbon tetra o b lo rid e so lu tio n In th e prasanoo o f bronlne and s ilv e r bronldo In vo lv es th e form ation o f styrene dlbroeddo and hydrogen bronldo# Tho organic bronldo th orafora raoon lsos In tho p rosm ee o f bromine, hydrogen bromldo, s ilv e r bronld

and styren e dlbroaide# The d lso u eslo n o f t h is raoa«

m lsatlon s t a r t s w ith a b r ie f aooount o f tho Walden hsvoralen In so fa r a s I t has a bearing on racém isation p roooseos. Thin I s follow ed by a b r ie f survey o f th e raoem ieatlon o f o p tlo a lly a c tiv e organlo halogen compounds In th e preeenoe o f tho o o rrespondlng h a lo g en s, hydrogen h a lid e s and a lk a li h a lid e s , f l* n a lly th o c a ta ly t ic e f f e c t o f s ilv e r s a lt s I s oonsld-ured#

«

40

-

3 . Kao8 a lB « tlo n aaâ th e Waldan Dxvm ralw.

la th e Wald a Z nversioa aa o p tlem lly a c tiv e coppoaad OabcZ l e ea b etltu ted hy aa atom or a group Y which e a te r s th e m eleoule la a p o s itio n d iffe r e n t from th a t o r ig in a lly oeou ;led hgr 1 , lea d in g t o a produot o f Inverted co n fig u ra tio n : OaboX > / ^

lOato ♦ X.

I t follovm Arom t h is th a t when th e s u b stltn tln g group I s id e n tic a l w ith the d isp laoed group X^ raosm im tion w ill r e su lt# fo r when h a lf th e mmhsr o f m oleoulss o f CahoX have hsim os#H verted in to XCabo th ere e x is t s a raoemlc m ixture o f equal am unts o f OahoX and XOabo# and th e r e a fte r th e r a te a t uhioh OahoZ i s changed in to XOaho w ill equal th e ra te o f th e o p p o site ®baage# sin oe th ere i s no d iffe r e n o e in th e r e a o t iv it ie s o f o p tic a l Isomers# A lso , th e v e lo c ity o f racém isation i s equal to tfvioe th e v e lo c ity o f in v e r sio n , sin o e th e inverm ion o f

Sx moles o f CaboX y ie ld s

2 6 % moles

o f the raoemate#

m cernieation hy such a mechanism i s th erefo re a s p e c ia l ca se o f the Walden Inversion# There Is no d ir e c t c o r r e la tio n between sig n o f r o ta tio n and ccm figuzution# S#g# th e s a lt s o f la ev o ro ta to ry la c t i e aoid «diich n eoes a r ily have th e same o o n fig n ra tio n as

aoid

are d extrorotatory f on th e o th er h^ndi, th e d i e th y l e s te r o f

«

41

«

la e v o ro ta to z y o h lo ro sn o o in lo ao ld im itm m lf I m e v o ^ ta to r y . fttrthozm ore» th e mlgn o f r o t a t i o n o f th e m olotion o f an o p tl o a ll y a c tiv e snbfitf^nofi may ehange w ith d i f f e r e n t eo lv en ta o r a t d lf « f e r o n t tom; o ra tn re a o± both# The f a c t ; th e r e f o r e ; t h a t in a r e a c tio n tm o p ti o a jl y a c tiv e ooaRrpcnnd i s converted in t o a n o th e r o p tlo a lly a c tiv e compound o f o p p o aito aig n o ‘ r o t a t i o n does n o t n e c o s e a rily in d lo a te t h a t a balden In v e rs io n ham ocoured# The c r i t e r i o n f o r th e ooeurence o f a * aldoa In v e rs io n i s (a) A oocapoimd i s co n v erted by two o r raora r e a c tio n s in t o i t s o p ti c a l Isomer# B#g# s i l v e r oxide g iv e s (-^) «m alic

)# ^ h lo ro sn o o in lo aold w ith m oist o ld # t h i s w ith phoephoras pent»»

c h lo rid e g iv e s (« )« o h lo ro e u o o ln ic

old (49)# a Walden In v e rs io n

m ast have ocoured in cme o r o th e r o f ^ e s e two re a c tio n s # T his was th e f i r s t example o f in v e rsio n # d isco v ered by Said an i n 1896# o r (b) O p tic a lly i s o m r i o forms o f a d e r iv a tiv e a re formed from an o p tlo a lly a c tiv e compound by th e u se o f d i f f e r e n t re#» gents# o r w ith th e same re a g e n t b u t und r d i f f e r e n t oonditi)«ohlorosoooinio a o id g iv e s (+)«m alio aoid# b a t w ith a;ueoue potassium hydroxide i t a f f o r d s (« )-m alic aold (50)# a Walden In V '^ slo n must have o ccu rs j w ith one o f th e s e r e a g e n ts . Again# in th e absence o f a so lv en t# (•)«of*phenylethyl a lc o h o l r e a o t s w ith hydrogen bromide a t «80® 0# t o g iv e (« î-o ^ p h e n y le th rl bromide# whereas a t teaq> eratures above «56® ( ^ ) «ot^pheny l e th y 1 bronld® i s

(51) •

•

42

•

In th e s e examples Invt^rslon imiat have oootxred â n r ln s one o r o th e r o f th e tv*o r e a c tio n s ^ b u t w ith o u t f u r t h e r knovAedge o f th e Tele’lltlo n sh lp between s ig n o f r o t a t i o n and o o n fig o ra tlo a i t l a n o t known vdiloh r e a c tio n caueos In v e rs io n and vdiioh r e ­ te n tio n o f c o n fig u ra tio n » A ttem pts to c o r r e l a t e s ig n o f ro ­ t a t i o n and c o n fig u r a tio n have b^en made^ among olA&erS; by fjrankland (52) on th e b a s is o f a s t a t i s t i c a l su rv e y . A ohes&ioal metbbd w is used by Kenyon awî r h i l l l p a which e s ta b lis h e d th e c o n fig u r a tio n o f many ooinponnds w ith a good d eg ree o f o e rta iB ty » T his m e^od i s based on th e assum ption t h a t a ohem ioal change which does n o t r u p tu re a lin k a g e o f th e asy w aetrio oar# bon i*tom oannot ^ I t e r th e c o n f ig t^ r a tio n .s h e r e a s I f one o f th e s e l i n k ges i s brokeh in v e rs io n may o c c u r. K .g. (^)-