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Reaction of polyisoprenes with bromine
R e a c t i o n of polyisoprtmes with 1)romiue
1073
(2) Ester plasticizcrs are hydrolysed completely by water formed in the l)roeess of thermal oxidation during the breakdown of hydrogen peroxides. (3) An increase in the rate of polyester hych'olysis during thermal oxidation, compared with hydrolysis without oxygen in steam, is due to the fact t h a t in the first ea.~e the process is not limited by the solubility of water in the polyester as a cons(,quenee of its formation in situ in the polymer. 'l'ransIated by E. SI~MERE REFERENCES
1. R. S. BARSHTEIN, I. I. LEVANTOVSKAYA, V. G. GORBUNOVA, M. P. YAZVIKOVA
a).l B. M. KOVARSKAYA,Plast. massy, No. 8, 47, 1967 2. K. A. ANDRIANOV, D. A. KARDASHEV, Praktieheskie raboty po iskusstvem~yn, smolam i plast,massam (Practical Studies of SyJ~thetie Resins and Plastics). p. 127, (los. nauehno-tekhnich, izd. khim. lit., 1946 3. M. B. NEIMAN, B. M. KOVARSKAYA, M. P. YAZV1KOVA, A. I. SIDNEV and M. S.
AKUTIN, Vysokomol. soyed. 3: 602, 1961 (Not translated in Polymer Sci. U.S.S.R.)
REACTION
OF POLYISOPRENES
WITH
BROMINE*
J. A. TUTORSKI[, L. V. SOKOLOVA' a l l d ]2~. A. I)O(~ADKIN M. V. L o m o n o s o v I n s t i t u t e of F i n e Chemical Technology, Moscow
(Received 25 December 1969)
NtTvlVmOUS studies deal with bromination of m~saturated polymers since this reaction is used for analytical purposes [1-9] and for the preparation of elastomers of bromobutyl rubber type [10]. There have been several studies of the bromination mechanism of cis-l,4-polyisoprene, [4, 11], trans-l,4-polyisoprene [12, 13] and cis-l,4-polybutadiene [14]. The addition mechanism of bromine to polyisoprene and the structure of the products of bromination now require careful examination. The effect of solvent and polar additives both on the reaction mechanism of one monomer unit (double bond) and on the macromolecular conformation in solution varying during the reaction should be taken into account. The purpose of this study is to explain the mechanism of bromination of polyisoprcnes by a detailed examination of the structure of bromination produets of polyisoprene at various stages of the reaction. EXPERIMENTAL Solvetg~s aild polyisoprene solutions were pl:~pared by the same m e t h o d as previously described [5]. 11% spectra were o b s e r v e d il~ a U R - 1 0 spectrograph. Specimens were p r e p a r e d by pouriug dilut~e solutions of bromides [it chloroform or bel~zeno on a K B r plate, followed "~ Vysokomol. soyed. A13: No. 4, 952-957,
1971.
1074
I.A.
T ~ r ~ o a s I ~ et al.
b y e v a p o r a t i o n o f s o l v e n t . S o m e s p e c i m e n s were p r e p a r e d b y c o m p r e s s i n g K B r pellets. I-Iigh r e s o l u t i o n N M R s p e c t r a were o b t a i n e d in a r a d i o s p e e t r o m e t e r d e v e l o p e d b y t h e Ce1~tral L a b o r a t o r y of A u t o m a t i o n (CLA) (60 Me/s). CHCI3 or CCI~ were u s e d as s o l v e n t a n d h e x a m e t h y l d i s i l o x a n e as fi~ternal s t a n d a r d . T h e b r o m i n e c o n t e n t of t h e p r o d u c t s o f b r o m i n a t i o n was d e t e r m i n e d b y m e t h o d s p r e v i o u s l y d e s c r i b e d [16]. D u r i n g b r o m i n a t i o n of ~ a t u r a l r u b b e r in CHCla, C6I-I 6 a n d CC14 b a n d s a p p e a r in t h e I R s p e c t r a a t 525 a n d 585 c m -~ repres,~x~tfilg s t r e t c h i n g v i b r a t i o n s of t h e C - - B r bo)~d (Fig. 1, s p e c t r u m 1, 2). T h e i n t e ) l s i t y of t h e s e b a n d s b~cre, ases w i t h increase iz~ r e a c t i o n t i m e . T h e I R s p e c t r a of b r o m i n a t e d g u t t a - p e r c h a cot~tam a stro~tg bated a t 545 e m ~ i n s t e a d of a b a ~ d a t 525 e m - t (Fig. 1, s p e c t r u m 3). It~ a d d i t i o n , a bm~d of a v e r a g e i n t e n s i t y a p p e a r s iu t h e s p e c t r a o f b r o m i n a t e d trans-l,4-polyisoprene a t 905 925 c m - t a n d b a n d s in t h e s p e c t r a of cis-l,4-polyisoprene b r o m i d e s a t 905-925 a n d 965 c m ~. T h e mte~tsity of t h e first of t h e s e barlds first increases a n d t h e ~ decreases, a n d as t h e c o m b i n e d b r o m i n e c o n t e n t itmreases t h i s b a n d is d i s p l a c e d to t h e s h o r t e r ~vaw~ region. T h e b a n d i n t e n s i t y a t 910 c m - t ir~creases u n t i l a 5 6 - 6 3 ~ b r o m i n e eontel~t is r e a c h e d in t h e p r o d u c t s a n d t h e ~ b e g i n s to decrease. To assign t h e b a n d a t 910 e m --~ iu IP~ s p e c t r a of p r o d u c t s of b r o m i n a t i o n o f p o l y i s o p r e n e s , t h e p r o d u c t s of b r o m i n a t i o n were ozonized. O z o n i z a t i o n r e s u l t e d in t h e c o m p l e t e d i s a p p e a r a n c e o f t h e b a n d a t 910 e m -~ a n d t h e a p p e a r m m e o f a s t r o ~ g b a n d -~t 1705 a n d 1110 c m -~ s u g g e s t i n g t h e f o r m a t i o ~ of g r o u p s contafifing o x y g e ~ (Fig. 1, s p e c t r u m 4). T h u s t h e b a n d a t 910 e m - t iI~ f a c t is d u e to tile pre, sence of d o u b l e b o n d s . T h e w e a k b a n d a t 1810 c m - t p r e s e n t in t h e s p e c t r a of b r o m i d e s e o n t a i t f i n g a fairly inte)~se b a n d a t 910 c m -~, is p r o b a b l y its o v e r t o n e . I t s h o u l d be ~ o t e d t h a t t h e i n t e n s i t y o f t h e bmtd a t 910 cnl ~ is h i g h e r d u r i n g b r o m i n a t i o n o f n a t u r a l r u b b e r i~ C,I{~ or CCI~ a n d lower in CHCla. D u r i n g b r o m i n a t i o n o f g u t t a - p e r c h a t h e i n t e n s i t y o f this b a n d v a r i e s in t h e s a m e way, b u t is a l w a y s m a r k e d l y h i g h e r t h m l in t h e s p e c t r a of b r o m i d e s of n a t u r a l r u b b e r . T h i s is fit s a t i s f a c t o r y a g r e e m e n t w i t h r e s u l t s of dctermi~fi~g c o m b b m d b r o m i n e in b r o m i d e s o f g u t t a - p e r c h a arid w i t h r e s u l t s eor~cerniug m e t h o x y brominatio)x of p o l y i s o p r e n e s [ 15]. H o w e v e r , e v e n t h e s p e c t r a o f p r o d u c t s of i n t e n s i v e b r o m i n a t i o n o f n a t u r a l r u b b e r w i t h a bromidic c o n t e n t ~ < 7 0 ~ h a v e a w e a k b a n d a t 910 c m -~ a n d a 1)a)td i~ t h e region of 1600 1700 e m -~. I ~ o t h e r words, t h e e n d p r o d u c t s o f b r o m i n a t i o n of n a t u r a l r u b b e r c o n t a i n a s m a l l n u m b e r of d o u b l e b o n d s . A c c o r d i n g to r e s u l t s in t h e l i t e r a t m ' e eoncemting t h e positi()n o f t h e b a n d e o r r e s p m M i n g to CH2 = C - - R ' X groups, where X is a halide, t'he b a n d a t 910 e m -~ s h o u l d be r e g a r d e d R as t h e r e s u l t of t h e f o r m a t i o n of e x o m e t h y l e ~ e g r o u p s b y b r o m i r t a t i o n of p o l y i s o p r e n e s [17, 19]. H i g h r e s o l u t i o ~ N1VIR s p e c t r a of b r o m i d e s of n a t u r a l r u b b e r a n d g u t t a - p e r c h a c o n t a i n a signal o f a b o u t 5.3 a n d 5.7 p . p . m , of v i n y l p r o t o n s arid 3'8 p . p . m , of m e t h i n e CHs p r o t o n s o f - - C H ~ - - C - - C J - I B r - - g r o u p s (Fig. 2). T h e effect of m e t h a n o l [15], p r e s e n t in t h e r e a c t i o n m e d i m n d u r i n g b r o m m a t i o n o f p o l y i s o p r e n e s o n t h e b a u d i n t e n s i t y a t 910 c m -1 indic a t e s t h a t e x o m e t h y l e n e g r o u p s are f o r m e d t h r o u g h b r o m o n i m n ions a c c e p t e d b y m e t h anol. T h e f o r m a t i o n o f e x o m e t h y l e n e g r o u p s is a c c o m p a n i e d b y t h e l i b e r a t i o n o f h y d r o g e n b r o m i d e . T h e process o f s u b s t i t u t i o n c a n b e s u p p r e s s e d to a large e x t e n t b y u s i n g p o l a r s o l v e n t s . Therefore, to determi~m q u a t ~ t i t a t i v e l y t h e d o u b l e b o n d s i~ p o l y i s o p r e n e , alcohol s h o u l d b e a d d e d to t h e c h l o r o f o r m s o l u t i o n .
The NMR and Ig spectra indicate that during brominatio~t gutta-percha ri~ig formation takes place. Thus, high resolution NMR
of natural rubber and spectra cow, rain signals
o f a b o u t 1-0 p . p . m . ( - - C H s in t h e ring), 1.2 p . p . m . ( - - ( ) H ~ - - i n t h e ring), 5.3 p . p . m . ( -=CFI in t h e ring) (Fig. 2) ['20]. T h e p r e s e n c e of b a n d s a t 8 6 0 - 8 7 0 m~d 3070 e m -~ is p r o b a b l y d u e
R e a c t i o n o f polyisopre~tes w i t h b r o m i u e
H t y p e [21]. T h e ba,nd at.
te t h e %rmatiol~ ill t h e r i n g s o f d o u b l e b o n d s of Cl-I3
\ /
lO75
/ C: C
"\
3070 c m ~ m a y , h o w e v e r , also be d u e to t h e p r e s e n c e of exom(~thylen(~ g r o u p s fit p r o d u c t s of bromiTmtion. D o u b l e b o n d s iu t h e rix~g are f o r m e d "~s a cot~sequenec of t h e stabiliza~io~ of a p s e u d o c y e l i e iol~ b y d e p r o t o n i z a t i o m T h u s , r i n g t i ) r m a t i o ~ of 1)olyisoprene d u r i n g b r o n m t a t i o l t is a secmtd source for t h e s e p m ' a t i o n of h y d r o g c u t)r(mfid(,. T h e pvese~ce of cyclic s t r u c t u r e s i,t b r o m i d e s of p o l y i s o p r e n e s is also i n d i r e c t l y p r o v c d by th(, fact t h a t t h e I R s p e c t r a of b r o m i d e fihns m a d e fi'om c h l o r o f o r m solutio~ts c o n t a i u s t r o n g ba~tds a t 765 an(l 1207 e m -1 d u e to solve~lt reterttioz~ [22]. B a n d izttensity increas(~s d u r i n g b r o i n i n a t i o n to "~ eertab~ l i m i t a n d t h e n r e m a i n s u n c h a n g e d . Ott h e a t i n g t h e fihns t h e i n t e ~ s i t y of th(.se b a n d s dcercascs m a r k e d l y (Fig. 3). Hox~ev('r, t h e s e ball(Is d~) n o t d i s a p p e a r c(mapletely. H e a t i n g fihns a t 60 ° is a c c o m p a n i e d b y n o t i c e a b l e c h a n g e s i~t l h c s t r u c t u r e of bromi(h,s of n a t u r M r u b b e r . A b a n d a p p e a r s i~t t h e s p e c t r m n a t 1405 cm- ~ a n d its mte~tsity iucroas(,s w i t h h e a t i r t g t i m e (in-plane d e f o r m a t i o n v i b r a t i o n s :CH), d u e to t h e t b r m a t i o n of - C H C H - - t y p e cis-double bottds as a r e s u l t of d e h y d r o b r o m i n a t i o n . T h e films b e c o m e d a r k e r (m h e a t i n g arid o n l y p a r t i a l l y dissolve in c h l o r o f o r m . Acc,)rding to N M R spectra., su bst itut i(,tt a n d r i n g formatior~ r e a c t i o n s t a k e place s i m u l t a n e o u s l y w i t h t h e a d d i t i o n of m o l e c u l a r b r o m i n e a t t h e d o u b l e b o n d (Fig. 2). T h e I1¢ s p e c t r a of p r o d u c t s of b r o m i n a t i o n of t h e cis- a n d trans-forms of p o l y i s o p r e n e differ coz*siderably, p a r t i c u l a r l y in t h e r a n g e of 400 to 700 e m ~. T h e s p e c t r u m of t h e cis-form
2
/
/
¢. t
3000t800
i
L
L
i
L
I
L
L
fSO0 1200
$
d
I
L
I
800 700 v, cm -~
FIG.
1
Z
500
--.
I
I
5
3 FIG.
I
2
FI( l. 1. I R s p e c t r a o f p r o d u c t s of b r o m m a t i o z l of cis-1,4- a n d trat+s-1,4-polyisoprelt~. N a t u r a l r u b b e r bromir~ated ilx CC14 at. r o o m t e m p e r a t u r e , eoutertt of c o m b i l m d b r o m i n e 59.8°/. (1) a n d 75'8~/o (2); g u t t a - p e r c h a b r o m i n a t e d irt CC14 a t 17 ), c o n t e n t of c~)mbil~ed bromfi~e 61"5~o (3); r~atural r u b b e r b r o m i d e (see Fig. 3) a f t e r ozo,liz a t i o a (4) m~d p r e v i o u s l y s u b j e c t e d to t h e effbct of iodiue (5). Fro. 2. NM~R s p e c t r a of p r o d u c t s of bromi~atiot~ of cis-l,4-and trans-l,4-polyisoprene: 1 - - n a t u r a l r u b b e r b r o m i n a t e d iu CHCI a a t 0 ~, contct~.t of c o m b i n e d t)romim~ 7 'Y,,; 2 - - n a t u r a l r u b b e r b r o m m a t e d in CHCls a t -- 10 ~, c o n t e r t t of combiI~ed b r o m i d e 67.5°~; 3 - - g u t t a - p e r c h a b r o m i n a t e d in CCI~ a t 17 , e o u t e , l t ~)[' e(m~bined b r o l n i n e 61.5 ~,,.
1076
I.A.
al.
T u T o R s ~ r r ~ et
contains absorption bands at 525, 545, 585, 965, 1206 and 1230 em -~, and the spectrum of the trans.form bands at 545, 1206, 1230 cm-L The causes of this difference will be discussed later.
2
1
I
i
I
I
1600
J
I
l
I
1200
|
I
800 v, cm-/
FIo. 3. Ii% spectra of products of bromir~ation of cis.l,4-polyisoprene. Natural rubber film b r o m ~ a t e d in CI-ICI8 at 0 °, content of combined bromine 71.3 ~ , after heating at 42 ° for 120 min (1) and after heating at 60 ° for 90 miu (2). To elucidate the structure of polyisoprene bromides, we brominated natural rubber previously treated with iodine. I t has been previously pointed out that natural rubber undergoes ring formation under the effect of iodine [23]. The I R spectra of brominated cyclo-rubber contain the same bands in the range of vibrations of the C - - H bond as those of brominated cis. and trans-polyisoprenes (Fig. 1, spectrum 5). This is additional evidence of the formation of cyclic structures during bromination of polyisoprene. We also carriec~ out bromination of a low molecular weight model of polyisoprenesqualene at 16 ° in a chloroform or carbon tetrachloride solution. NIV£R spectra were obtained
U I
5
g
I
~p~rn.
FIO. 4. ~TMR spectra of squalene subjected to varying degrees of bromination.
Reactioa of polyisopreaes with bromine
1077
of the, products of bromination of squalcne with different degrees of bromination. Variations m the spectrum of squalene are due t,o tile appearal~ce of signals of about 0.9 (--CILIa) and 1.2 p.p.m. (--CH.,--), correspoi~dfi~g to cyclic structures, and signals of about 1-83-1.9 (CHs-- ()Br), 3.8 ( - - C - - C H B r - - ) , 4.1 ( - - C t t B r - - ) , 5.3 and 5.7 p.p.m. (~ C H B r ) , d u e to the
I
CH~ additio~t of bromine and to substitutioi~ (Fig. 4). W i t h a~ irtcrease H~ the degree of bromir~ation two sigr~als of about 1.63 and 2.0 are converted to at~ asymmetrical sig~al of 1.8-1.9 a~td 2.0, while the signal of about 5.06 ( : - C H - - ) completely disappears (Fig. 4). During bromination of squalene, as with bromination of polyisopre~es, the additiot~ of moleeHlar I00
2O I
I
I
I ~i I
I
I
i
[
3000 2800 1700
~
I
130
i
l
±±.._L
,900700
. A _~--__
50,9 V~ Cf'D -!
:FIG. 5. I R spectrum of squalene brominated in CCI4 at -- 16 °. bromine at file double bot~d is accompanied by partial ring ibrmatio~ a a d substitution, which results in the liberation of hydrogen bromide. The I R spectrum of brominated squalene is showrt in Fig. 5. As with bromination of tr~s-polyisoprelm, an intense bm~d appears i~t the spectrum at 545 cm -~, the band at 840 em -~ corresponding to double bonds disappears, bands appear at 880 era-~ (cyclic structures) and 910 em -1 (exomethylelm groups). RESULTS
B r o m i n a t i o n o f p o l y i s o p r e n e s is a c o m p l e x r e a c t i o n , w h i c h in t h e i n i t i a l s t a g e takes place by a mechanism of electrophilic addition to the double bond. At this stage the bromine molecule may form a complex with charge transfer both with the double bond of the polymer and with the solvent. Complex formation was noted in particular between bromine and benzene of 1 : 1 composition with a m e l t i n g p o i n t o f - - 1 4 ° [24]. T h e p o s s i b i l i t y o f p r e p a r i n g b r o m o m e t h o x y l a t e d p r o d u c t s o f p o l y i s o p r e n e s b y d i r e c t i n t e r a c t i o n o f t/ n u c h , o p h i l i c a g e n t s u c h a s methanol and molecular bromine with a double bond serves as irrefutable evidence of the two-stage mechanism of bromination. Ctt3 a+ a--CH2--C=CH--CH2 5-I-
+Br--Br...solvent
(Br~ or
5--
I ~ - - b r o m i n a t i o n catalyst) -~ CI-I~
I
~--CH2--C---CH
CH2--+Br~)
Br
I t is n a t u r a l t o e x p e c t t h a t t h e s o l v e n t will n o t i c e a b l y i n f l u e n c e t h e s u b s e q u e n t c o u r s e o f t h e r e a c t i o n , s i n c e a n i n c r e a s e in s o l v e n t p o l a r i t y r e d u c e s t h e i o n i c
1078
[. A. TUTORSKII et al.
charge of the bromonium ion [25]. When bromination is carried out in non-polar solvents such as benzene or carbon tetrachloride H B r separates more intensively, i.e. the proportion of secondary reactions of substitution and ring formation is larger in this case. A reduction in band intensity at 910 cm -1 during bromination is particularly marked with a considerable bromine excess, long reaction time or at high temperature. This fact may indicate that the exomethylene groups are used up as a consequence of the addition of bromine. A product of the following composition is formed Br CI-I2 Br
I
--CtI2--C--J--CH2-- ,
i
]
Br
H
which contains 78-2% of combined bromine. From the results obtained the following system of bromination of polyisoprenes can be derived CI~I3 --CII2--C--~ CH--CH~---
~- Br-- B r -*
CH3 slowly I - - - - ~ - - C t t 2--C--CH- - CHs-- - - ÷ Br ® (~xx
~x.,x
Br -H®
quickly slowly
quickly . _ _ _
C]-I3
I
--CH~--C--
i
Br
Br
I
i
--C--CH2-H
CH3
--H~C
II
--CH~-C
\/
CH
i
l
Br
f
CIt2
C
/®
/
BrttC
CH
i
I +Brz
Br H
II
tt2C
C
\c / \ell3 tt2
BrCH2 Br
f I - - C H ~ - - (3-- C--CH2 [ ]
CH2--
I
- n Q [ quickly H~C
Ctta
\/ C
/\ BrHC
/
CH~--
CH
l
i
H~C
C
\cf\ H
CH~
Reaction of polyisoprenos with 1)romme
1079
The b r o m i n e molecule forms complexes with charge transfer with the polyisoprene double b o n d a n d with the solvent. The b r o m i n e - p o l y m e r complex is slowly c o n v e r t e d to a b r o m o n i u m ion which is stabilized as a. result of intermolecular liberation of H B r to form m o n o b r o m i d e c o n t a i n i n g e x o m e t h y l e n e groups. The intermolecular addition of bromine to lhe b r o m o n i u m ion to form d i b r o m i d e takes place v e r y rapidly. The dibromide is the main reaction p r o d u c t which contains 70-12°/o c o m b i n e d bromine. The b r o m o n i u m ion is subject to ring formatioll to form a pseudo-cyclic ion. The latter is stabilized to form a s i x - m e m b e r e d ring b y depr()tonization, which is an additionM source for the f o r m a t i o n of H~Br. The e x o m e t h y l e n e groups f o r m e d can s u b s e q u e n t l y combine bromine, although with m u c h more difficulty t h a n the m e t h y l a t c d double b o n d [26]. The latter results in the f o r m a t i o n of tribromide. CONCLUSIONS
(1) A s t u d y was made of the s t r u c t u r e of p r o d u c t s of b r o m i n a t i o n of cisand trans-polyisoprenes a n d squalene in a solution of benzene and chloroform at various stages of the reaction using I R s p e c t r o s c o p y and high resolution NMR,. (2) Processes of s u b s t i t u t i o n t a k i n g place r a p i d l y a n d simultaneously with a d d i t i o n to the double b o n d result in the t b r m a t i o n of e x o m e t h y l e n e groups a n d intramoleetflar cyclic structm'es. (3) The sh)w a d d i t i o n of bromine to vinylidene double bonds results in the f o r m a t i o n of the t r i b r o m i d e CaHTBr a. (4) A difference was observed in the s t r u c t u r e of p r o d u c t s of b r o m i n a t i o n of t:is- ~md trans-polyisoprenes a n d a s y s t e m is I)roposcd to rel)rcscnt the rearetions t a k i n g place dm'ing b r o m i n a i i ( m of p(~lyisel)rene.
Tra~sl(Itt~d by E. SEMERE R~:FI:R£NCI:S 1. W. K. LEWIS, W. H. McADAMS, lt~dustr. "rod Engng. Cicero. 12: 673, 1920 2. l-I. L. FISHER, G. GRAY and R. MELTING, h~dustr. ~md Engng. Ckem. 13: 1031, 1921 3. (L O. WILLITS, M. Z. SWAIN and C. L. 0GG, gubb¢,r. ('h(~m. ~md Technol. 20: 320, 1947
4. W. J. GOWANS and F. E. CLARK, l{ubber Chem. ~md Teclmo]. 25: 961, 1952 5. F. J. MAFFEL, M. OUTA, Rubber. Chem. and Technol. 23: 457, 1950 6. J. W. MEEKS, R. V. CROOK, C. E. PARDO and F. E. CLARK, A~lalyt.. Chem. 25: 1536, 195"1 7. G. T. DAROVSKIKH and G. A. TROFIMOV, Kauchuk i rezma, ~No. l 1, 4S, 1963 8. T. J. B A K E R , L. G. LAYKO, R. D. STUBBLEFIELD m~d R . F . ANDERSON, An~lyt. Biochem. 2: 287, 1961 9. K. R. MIDDLETON, Anal.~ st 88: 368, 1963 10. R. T. MORRISEY, Industr. and Engng. Chem. 47: 1562, 1955 I I. C. PINAZZI, G. GUENIFFEY and J. BROSSAS, Compt. rend. 258: 4982, 1964 12. G. F. BLOOMFIELD, J. Soc. Chem. I~tdustr. transacv. 64: 274, 1945 l'k ]-I. STAUDINGER and I-I. STAUDINGER, Rubber ('h¢ml. and Technol. I7: 15, 1944 14. N. A. PLATE, TRAN KI-I'EY, V. P. SHIBAYEV and V. A. KARGIN, Vysok(mlol. soy¢~d. 7: 152,% 1965 (Tr~n.~lat~,(t in Polym~,r S(d. [T.S.S.I£. 7: 9. 1683, 1965)
1080
V . V . GUZEYEV et al.
15. I. A. TUTOItSKII, L. V. SOKOLOVA and B. A. DOGADKIN, Uchenye zapiski, No. 2, 33, 1961 16. G. A. CHELISHEVA, G. M. CHEBYSHEVA and G. P. SHCHERBACHEV, Kauchuk i rezina, No. 2, 33, 1961 17. G. SALOMON, A. Chr. VAN DER SCHEE, J. A. A. KETELAAR and B. J. VAN EYK, Disc. Faraday See., :No. 9, 291, 1950 18. L. BELLAMY, Infrakrasnye spektry slozhnykh molekul (IR Spectra of Complex Molecules). Izd. inostr, lit., 1963 19. Yu. A. PENTIN, E. V. MOItOZOV and Z. SHARIPOV, Vestn. MGU, No. 2, 23, 1966 20. I. A. TUTOItSKII, I. Ya. SLONIM, E. G. BOIKACHEVA, O. A. MOCHALOVA, L. V. SOKOLOVA and B. A. DOGADKIN, Vysokomol. soyed. A10: 592, 1968 (Translated in Polymer Sci. U.S.S.R. 10: 3, 692, 1968) 21. M. STOLKA, J. VODEHNAL and J. K(iSSLER, J. :Polymer Sci. A2: 3987, 1964 22. M. V. EVANS, G. N. C. HIGGINS, D. F. LEE and W. F. WATSON, J. Appl. :Polymer Sci. 4: 367, 1960 23. I. A. TUTORSKII, L. V. SOKOLOVA and B. A. DOGADKIN, Kolloidn. zh. 32: 590, 1970 24. L. ANDREWS and It. KIFER, Molekulyarnye kompleksy v organicheskoi khimii (Molecular Complexes in Organic Chemistry). Izd. "Mir", 1967 25. K. D. NENITSESKU, Organicheskaya khimiya (Organic Chemistry). Vol. 1, p. 389, Izd. inostr, lit., 1962 26. B. E. SWEDLUND and P. W. ItOBEItTSON, J. Chem. See., 630, 1947
THERMODYNAMICS OF THE DEFORMATION OF PLASTICIZED POLYVINYLCHLORIDE FILLED WITH AEROSIL AND KAOLIN* V. V. GUZEYEV, ZH. I. SHKALENKO, YU. M. MALINSKII a n d V. A. KARGIN (dec.) (Received 26 December 1969)
IT tlAS been r e p o r t e d [1] t h a t the addition of finely dispersed silica aerosil to plasticized p o l y v i n y l c h l o r i d e composition m a r k e d l y alters certain properties of the polymer. A n a t t e m p t was m a d e in this s t u d y to examine high-elastic d e f o r m a t i o n of plasticized polyvinylchloride filled with aerosil a n d kaolin, which differ in chemical composition, degree of dispersion a n d o t h e r properties. Owing to these differences it can be expected t h a t aerosil a n d kaolin will h a v e different effects on the elast i c i t y of filled plasticized polyvinylchloride (PVC). EXPERIMENTALt
The samples contained 100 parts by weight S-75 PVC (molecular weight 100,000), 50 parts by weight didecylphthalate plasticizer, 8 parts by weight dibasic lead phthalate m~d dibasic lead stearate stabilizers and 0.3 parts by weight diphenylolpropaae aatioxidant. * Vysokomol. soyed. A13: No. 4, 958-965, 1971. t L. M. Marty~lova, N. P. Urtmir~tseva and L. V. Medvedeva took part i~ the experinl(~tlts.
1073
(2) Ester plasticizcrs are hydrolysed completely by water formed in the l)roeess of thermal oxidation during the breakdown of hydrogen peroxides. (3) An increase in the rate of polyester hych'olysis during thermal oxidation, compared with hydrolysis without oxygen in steam, is due to the fact t h a t in the first ea.~e the process is not limited by the solubility of water in the polyester as a cons(,quenee of its formation in situ in the polymer. 'l'ransIated by E. SI~MERE REFERENCES
1. R. S. BARSHTEIN, I. I. LEVANTOVSKAYA, V. G. GORBUNOVA, M. P. YAZVIKOVA
a).l B. M. KOVARSKAYA,Plast. massy, No. 8, 47, 1967 2. K. A. ANDRIANOV, D. A. KARDASHEV, Praktieheskie raboty po iskusstvem~yn, smolam i plast,massam (Practical Studies of SyJ~thetie Resins and Plastics). p. 127, (los. nauehno-tekhnich, izd. khim. lit., 1946 3. M. B. NEIMAN, B. M. KOVARSKAYA, M. P. YAZV1KOVA, A. I. SIDNEV and M. S.
AKUTIN, Vysokomol. soyed. 3: 602, 1961 (Not translated in Polymer Sci. U.S.S.R.)
REACTION
OF POLYISOPRENES
WITH
BROMINE*
J. A. TUTORSKI[, L. V. SOKOLOVA' a l l d ]2~. A. I)O(~ADKIN M. V. L o m o n o s o v I n s t i t u t e of F i n e Chemical Technology, Moscow
(Received 25 December 1969)
NtTvlVmOUS studies deal with bromination of m~saturated polymers since this reaction is used for analytical purposes [1-9] and for the preparation of elastomers of bromobutyl rubber type [10]. There have been several studies of the bromination mechanism of cis-l,4-polyisoprene, [4, 11], trans-l,4-polyisoprene [12, 13] and cis-l,4-polybutadiene [14]. The addition mechanism of bromine to polyisoprene and the structure of the products of bromination now require careful examination. The effect of solvent and polar additives both on the reaction mechanism of one monomer unit (double bond) and on the macromolecular conformation in solution varying during the reaction should be taken into account. The purpose of this study is to explain the mechanism of bromination of polyisoprcnes by a detailed examination of the structure of bromination produets of polyisoprene at various stages of the reaction. EXPERIMENTAL Solvetg~s aild polyisoprene solutions were pl:~pared by the same m e t h o d as previously described [5]. 11% spectra were o b s e r v e d il~ a U R - 1 0 spectrograph. Specimens were p r e p a r e d by pouriug dilut~e solutions of bromides [it chloroform or bel~zeno on a K B r plate, followed "~ Vysokomol. soyed. A13: No. 4, 952-957,
1971.
1074
I.A.
T ~ r ~ o a s I ~ et al.
b y e v a p o r a t i o n o f s o l v e n t . S o m e s p e c i m e n s were p r e p a r e d b y c o m p r e s s i n g K B r pellets. I-Iigh r e s o l u t i o n N M R s p e c t r a were o b t a i n e d in a r a d i o s p e e t r o m e t e r d e v e l o p e d b y t h e Ce1~tral L a b o r a t o r y of A u t o m a t i o n (CLA) (60 Me/s). CHCI3 or CCI~ were u s e d as s o l v e n t a n d h e x a m e t h y l d i s i l o x a n e as fi~ternal s t a n d a r d . T h e b r o m i n e c o n t e n t of t h e p r o d u c t s o f b r o m i n a t i o n was d e t e r m i n e d b y m e t h o d s p r e v i o u s l y d e s c r i b e d [16]. D u r i n g b r o m i n a t i o n of ~ a t u r a l r u b b e r in CHCla, C6I-I 6 a n d CC14 b a n d s a p p e a r in t h e I R s p e c t r a a t 525 a n d 585 c m -~ repres,~x~tfilg s t r e t c h i n g v i b r a t i o n s of t h e C - - B r bo)~d (Fig. 1, s p e c t r u m 1, 2). T h e i n t e ) l s i t y of t h e s e b a n d s b~cre, ases w i t h increase iz~ r e a c t i o n t i m e . T h e I R s p e c t r a of b r o m i n a t e d g u t t a - p e r c h a cot~tam a stro~tg bated a t 545 e m ~ i n s t e a d of a b a ~ d a t 525 e m - t (Fig. 1, s p e c t r u m 3). It~ a d d i t i o n , a bm~d of a v e r a g e i n t e n s i t y a p p e a r s iu t h e s p e c t r a o f b r o m i n a t e d trans-l,4-polyisoprene a t 905 925 c m - t a n d b a n d s in t h e s p e c t r a of cis-l,4-polyisoprene b r o m i d e s a t 905-925 a n d 965 c m ~. T h e mte~tsity of t h e first of t h e s e barlds first increases a n d t h e ~ decreases, a n d as t h e c o m b i n e d b r o m i n e c o n t e n t itmreases t h i s b a n d is d i s p l a c e d to t h e s h o r t e r ~vaw~ region. T h e b a n d i n t e n s i t y a t 910 c m - t ir~creases u n t i l a 5 6 - 6 3 ~ b r o m i n e eontel~t is r e a c h e d in t h e p r o d u c t s a n d t h e ~ b e g i n s to decrease. To assign t h e b a n d a t 910 e m --~ iu IP~ s p e c t r a of p r o d u c t s of b r o m i n a t i o n o f p o l y i s o p r e n e s , t h e p r o d u c t s of b r o m i n a t i o n were ozonized. O z o n i z a t i o n r e s u l t e d in t h e c o m p l e t e d i s a p p e a r a n c e o f t h e b a n d a t 910 e m -~ a n d t h e a p p e a r m m e o f a s t r o ~ g b a n d -~t 1705 a n d 1110 c m -~ s u g g e s t i n g t h e f o r m a t i o ~ of g r o u p s contafifing o x y g e ~ (Fig. 1, s p e c t r u m 4). T h u s t h e b a n d a t 910 e m - t iI~ f a c t is d u e to tile pre, sence of d o u b l e b o n d s . T h e w e a k b a n d a t 1810 c m - t p r e s e n t in t h e s p e c t r a of b r o m i d e s e o n t a i t f i n g a fairly inte)~se b a n d a t 910 c m -~, is p r o b a b l y its o v e r t o n e . I t s h o u l d be ~ o t e d t h a t t h e i n t e n s i t y o f t h e bmtd a t 910 cnl ~ is h i g h e r d u r i n g b r o m i n a t i o n o f n a t u r a l r u b b e r i~ C,I{~ or CCI~ a n d lower in CHCla. D u r i n g b r o m i n a t i o n o f g u t t a - p e r c h a t h e i n t e n s i t y o f this b a n d v a r i e s in t h e s a m e way, b u t is a l w a y s m a r k e d l y h i g h e r t h m l in t h e s p e c t r a of b r o m i d e s of n a t u r a l r u b b e r . T h i s is fit s a t i s f a c t o r y a g r e e m e n t w i t h r e s u l t s of dctermi~fi~g c o m b b m d b r o m i n e in b r o m i d e s o f g u t t a - p e r c h a arid w i t h r e s u l t s eor~cerniug m e t h o x y brominatio)x of p o l y i s o p r e n e s [ 15]. H o w e v e r , e v e n t h e s p e c t r a o f p r o d u c t s of i n t e n s i v e b r o m i n a t i o n o f n a t u r a l r u b b e r w i t h a bromidic c o n t e n t ~ < 7 0 ~ h a v e a w e a k b a n d a t 910 c m -~ a n d a 1)a)td i~ t h e region of 1600 1700 e m -~. I ~ o t h e r words, t h e e n d p r o d u c t s o f b r o m i n a t i o n of n a t u r a l r u b b e r c o n t a i n a s m a l l n u m b e r of d o u b l e b o n d s . A c c o r d i n g to r e s u l t s in t h e l i t e r a t m ' e eoncemting t h e positi()n o f t h e b a n d e o r r e s p m M i n g to CH2 = C - - R ' X groups, where X is a halide, t'he b a n d a t 910 e m -~ s h o u l d be r e g a r d e d R as t h e r e s u l t of t h e f o r m a t i o n of e x o m e t h y l e ~ e g r o u p s b y b r o m i r t a t i o n of p o l y i s o p r e n e s [17, 19]. H i g h r e s o l u t i o ~ N1VIR s p e c t r a of b r o m i d e s of n a t u r a l r u b b e r a n d g u t t a - p e r c h a c o n t a i n a signal o f a b o u t 5.3 a n d 5.7 p . p . m , of v i n y l p r o t o n s arid 3'8 p . p . m , of m e t h i n e CHs p r o t o n s o f - - C H ~ - - C - - C J - I B r - - g r o u p s (Fig. 2). T h e effect of m e t h a n o l [15], p r e s e n t in t h e r e a c t i o n m e d i m n d u r i n g b r o m m a t i o n o f p o l y i s o p r e n e s o n t h e b a u d i n t e n s i t y a t 910 c m -1 indic a t e s t h a t e x o m e t h y l e n e g r o u p s are f o r m e d t h r o u g h b r o m o n i m n ions a c c e p t e d b y m e t h anol. T h e f o r m a t i o n o f e x o m e t h y l e n e g r o u p s is a c c o m p a n i e d b y t h e l i b e r a t i o n o f h y d r o g e n b r o m i d e . T h e process o f s u b s t i t u t i o n c a n b e s u p p r e s s e d to a large e x t e n t b y u s i n g p o l a r s o l v e n t s . Therefore, to determi~m q u a t ~ t i t a t i v e l y t h e d o u b l e b o n d s i~ p o l y i s o p r e n e , alcohol s h o u l d b e a d d e d to t h e c h l o r o f o r m s o l u t i o n .
The NMR and Ig spectra indicate that during brominatio~t gutta-percha ri~ig formation takes place. Thus, high resolution NMR
of natural rubber and spectra cow, rain signals
o f a b o u t 1-0 p . p . m . ( - - C H s in t h e ring), 1.2 p . p . m . ( - - ( ) H ~ - - i n t h e ring), 5.3 p . p . m . ( -=CFI in t h e ring) (Fig. 2) ['20]. T h e p r e s e n c e of b a n d s a t 8 6 0 - 8 7 0 m~d 3070 e m -~ is p r o b a b l y d u e
R e a c t i o n o f polyisopre~tes w i t h b r o m i u e
H t y p e [21]. T h e ba,nd at.
te t h e %rmatiol~ ill t h e r i n g s o f d o u b l e b o n d s of Cl-I3
\ /
lO75
/ C: C
"\
3070 c m ~ m a y , h o w e v e r , also be d u e to t h e p r e s e n c e of exom(~thylen(~ g r o u p s fit p r o d u c t s of bromiTmtion. D o u b l e b o n d s iu t h e rix~g are f o r m e d "~s a cot~sequenec of t h e stabiliza~io~ of a p s e u d o c y e l i e iol~ b y d e p r o t o n i z a t i o m T h u s , r i n g t i ) r m a t i o ~ of 1)olyisoprene d u r i n g b r o n m t a t i o l t is a secmtd source for t h e s e p m ' a t i o n of h y d r o g c u t)r(mfid(,. T h e pvese~ce of cyclic s t r u c t u r e s i,t b r o m i d e s of p o l y i s o p r e n e s is also i n d i r e c t l y p r o v c d by th(, fact t h a t t h e I R s p e c t r a of b r o m i d e fihns m a d e fi'om c h l o r o f o r m solutio~ts c o n t a i u s t r o n g ba~tds a t 765 an(l 1207 e m -1 d u e to solve~lt reterttioz~ [22]. B a n d izttensity increas(~s d u r i n g b r o i n i n a t i o n to "~ eertab~ l i m i t a n d t h e n r e m a i n s u n c h a n g e d . Ott h e a t i n g t h e fihns t h e i n t e ~ s i t y of th(.se b a n d s dcercascs m a r k e d l y (Fig. 3). Hox~ev('r, t h e s e ball(Is d~) n o t d i s a p p e a r c(mapletely. H e a t i n g fihns a t 60 ° is a c c o m p a n i e d b y n o t i c e a b l e c h a n g e s i~t l h c s t r u c t u r e of bromi(h,s of n a t u r M r u b b e r . A b a n d a p p e a r s i~t t h e s p e c t r m n a t 1405 cm- ~ a n d its mte~tsity iucroas(,s w i t h h e a t i r t g t i m e (in-plane d e f o r m a t i o n v i b r a t i o n s :CH), d u e to t h e t b r m a t i o n of - C H C H - - t y p e cis-double bottds as a r e s u l t of d e h y d r o b r o m i n a t i o n . T h e films b e c o m e d a r k e r (m h e a t i n g arid o n l y p a r t i a l l y dissolve in c h l o r o f o r m . Acc,)rding to N M R spectra., su bst itut i(,tt a n d r i n g formatior~ r e a c t i o n s t a k e place s i m u l t a n e o u s l y w i t h t h e a d d i t i o n of m o l e c u l a r b r o m i n e a t t h e d o u b l e b o n d (Fig. 2). T h e I1¢ s p e c t r a of p r o d u c t s of b r o m i n a t i o n of t h e cis- a n d trans-forms of p o l y i s o p r e n e differ coz*siderably, p a r t i c u l a r l y in t h e r a n g e of 400 to 700 e m ~. T h e s p e c t r u m of t h e cis-form
2
/
/
¢. t
3000t800
i
L
L
i
L
I
L
L
fSO0 1200
$
d
I
L
I
800 700 v, cm -~
FIG.
1
Z
500
--.
I
I
5
3 FIG.
I
2
FI( l. 1. I R s p e c t r a o f p r o d u c t s of b r o m m a t i o z l of cis-1,4- a n d trat+s-1,4-polyisoprelt~. N a t u r a l r u b b e r bromir~ated ilx CC14 at. r o o m t e m p e r a t u r e , eoutertt of c o m b i l m d b r o m i n e 59.8°/. (1) a n d 75'8~/o (2); g u t t a - p e r c h a b r o m i n a t e d irt CC14 a t 17 ), c o n t e n t of c~)mbil~ed bromfi~e 61"5~o (3); r~atural r u b b e r b r o m i d e (see Fig. 3) a f t e r ozo,liz a t i o a (4) m~d p r e v i o u s l y s u b j e c t e d to t h e effbct of iodiue (5). Fro. 2. NM~R s p e c t r a of p r o d u c t s of bromi~atiot~ of cis-l,4-and trans-l,4-polyisoprene: 1 - - n a t u r a l r u b b e r b r o m i n a t e d iu CHCI a a t 0 ~, contct~.t of c o m b i n e d t)romim~ 7 'Y,,; 2 - - n a t u r a l r u b b e r b r o m m a t e d in CHCls a t -- 10 ~, c o n t e r t t of combiI~ed b r o m i d e 67.5°~; 3 - - g u t t a - p e r c h a b r o m i n a t e d in CCI~ a t 17 , e o u t e , l t ~)[' e(m~bined b r o l n i n e 61.5 ~,,.
1076
I.A.
al.
T u T o R s ~ r r ~ et
contains absorption bands at 525, 545, 585, 965, 1206 and 1230 em -~, and the spectrum of the trans.form bands at 545, 1206, 1230 cm-L The causes of this difference will be discussed later.
2
1
I
i
I
I
1600
J
I
l
I
1200
|
I
800 v, cm-/
FIo. 3. Ii% spectra of products of bromir~ation of cis.l,4-polyisoprene. Natural rubber film b r o m ~ a t e d in CI-ICI8 at 0 °, content of combined bromine 71.3 ~ , after heating at 42 ° for 120 min (1) and after heating at 60 ° for 90 miu (2). To elucidate the structure of polyisoprene bromides, we brominated natural rubber previously treated with iodine. I t has been previously pointed out that natural rubber undergoes ring formation under the effect of iodine [23]. The I R spectra of brominated cyclo-rubber contain the same bands in the range of vibrations of the C - - H bond as those of brominated cis. and trans-polyisoprenes (Fig. 1, spectrum 5). This is additional evidence of the formation of cyclic structures during bromination of polyisoprene. We also carriec~ out bromination of a low molecular weight model of polyisoprenesqualene at 16 ° in a chloroform or carbon tetrachloride solution. NIV£R spectra were obtained
U I
5
g
I
~p~rn.
FIO. 4. ~TMR spectra of squalene subjected to varying degrees of bromination.
Reactioa of polyisopreaes with bromine
1077
of the, products of bromination of squalcne with different degrees of bromination. Variations m the spectrum of squalene are due t,o tile appearal~ce of signals of about 0.9 (--CILIa) and 1.2 p.p.m. (--CH.,--), correspoi~dfi~g to cyclic structures, and signals of about 1-83-1.9 (CHs-- ()Br), 3.8 ( - - C - - C H B r - - ) , 4.1 ( - - C t t B r - - ) , 5.3 and 5.7 p.p.m. (~ C H B r ) , d u e to the
I
CH~ additio~t of bromine and to substitutioi~ (Fig. 4). W i t h a~ irtcrease H~ the degree of bromir~ation two sigr~als of about 1.63 and 2.0 are converted to at~ asymmetrical sig~al of 1.8-1.9 a~td 2.0, while the signal of about 5.06 ( : - C H - - ) completely disappears (Fig. 4). During bromination of squalene, as with bromination of polyisopre~es, the additiot~ of moleeHlar I00
2O I
I
I
I ~i I
I
I
i
[
3000 2800 1700
~
I
130
i
l
±±.._L
,900700
. A _~--__
50,9 V~ Cf'D -!
:FIG. 5. I R spectrum of squalene brominated in CCI4 at -- 16 °. bromine at file double bot~d is accompanied by partial ring ibrmatio~ a a d substitution, which results in the liberation of hydrogen bromide. The I R spectrum of brominated squalene is showrt in Fig. 5. As with bromination of tr~s-polyisoprelm, an intense bm~d appears i~t the spectrum at 545 cm -~, the band at 840 em -~ corresponding to double bonds disappears, bands appear at 880 era-~ (cyclic structures) and 910 em -1 (exomethylelm groups). RESULTS
B r o m i n a t i o n o f p o l y i s o p r e n e s is a c o m p l e x r e a c t i o n , w h i c h in t h e i n i t i a l s t a g e takes place by a mechanism of electrophilic addition to the double bond. At this stage the bromine molecule may form a complex with charge transfer both with the double bond of the polymer and with the solvent. Complex formation was noted in particular between bromine and benzene of 1 : 1 composition with a m e l t i n g p o i n t o f - - 1 4 ° [24]. T h e p o s s i b i l i t y o f p r e p a r i n g b r o m o m e t h o x y l a t e d p r o d u c t s o f p o l y i s o p r e n e s b y d i r e c t i n t e r a c t i o n o f t/ n u c h , o p h i l i c a g e n t s u c h a s methanol and molecular bromine with a double bond serves as irrefutable evidence of the two-stage mechanism of bromination. Ctt3 a+ a--CH2--C=CH--CH2 5-I-
+Br--Br...solvent
(Br~ or
5--
I ~ - - b r o m i n a t i o n catalyst) -~ CI-I~
I
~--CH2--C---CH
CH2--+Br~)
Br
I t is n a t u r a l t o e x p e c t t h a t t h e s o l v e n t will n o t i c e a b l y i n f l u e n c e t h e s u b s e q u e n t c o u r s e o f t h e r e a c t i o n , s i n c e a n i n c r e a s e in s o l v e n t p o l a r i t y r e d u c e s t h e i o n i c
1078
[. A. TUTORSKII et al.
charge of the bromonium ion [25]. When bromination is carried out in non-polar solvents such as benzene or carbon tetrachloride H B r separates more intensively, i.e. the proportion of secondary reactions of substitution and ring formation is larger in this case. A reduction in band intensity at 910 cm -1 during bromination is particularly marked with a considerable bromine excess, long reaction time or at high temperature. This fact may indicate that the exomethylene groups are used up as a consequence of the addition of bromine. A product of the following composition is formed Br CI-I2 Br
I
--CtI2--C--J--CH2-- ,
i
]
Br
H
which contains 78-2% of combined bromine. From the results obtained the following system of bromination of polyisoprenes can be derived CI~I3 --CII2--C--~ CH--CH~---
~- Br-- B r -*
CH3 slowly I - - - - ~ - - C t t 2--C--CH- - CHs-- - - ÷ Br ® (~xx
~x.,x
Br -H®
quickly slowly
quickly . _ _ _
C]-I3
I
--CH~--C--
i
Br
Br
I
i
--C--CH2-H
CH3
--H~C
II
--CH~-C
\/
CH
i
l
Br
f
CIt2
C
/®
/
BrttC
CH
i
I +Brz
Br H
II
tt2C
C
\c / \ell3 tt2
BrCH2 Br
f I - - C H ~ - - (3-- C--CH2 [ ]
CH2--
I
- n Q [ quickly H~C
Ctta
\/ C
/\ BrHC
/
CH~--
CH
l
i
H~C
C
\cf\ H
CH~
Reaction of polyisoprenos with 1)romme
1079
The b r o m i n e molecule forms complexes with charge transfer with the polyisoprene double b o n d a n d with the solvent. The b r o m i n e - p o l y m e r complex is slowly c o n v e r t e d to a b r o m o n i u m ion which is stabilized as a. result of intermolecular liberation of H B r to form m o n o b r o m i d e c o n t a i n i n g e x o m e t h y l e n e groups. The intermolecular addition of bromine to lhe b r o m o n i u m ion to form d i b r o m i d e takes place v e r y rapidly. The dibromide is the main reaction p r o d u c t which contains 70-12°/o c o m b i n e d bromine. The b r o m o n i u m ion is subject to ring formatioll to form a pseudo-cyclic ion. The latter is stabilized to form a s i x - m e m b e r e d ring b y depr()tonization, which is an additionM source for the f o r m a t i o n of H~Br. The e x o m e t h y l e n e groups f o r m e d can s u b s e q u e n t l y combine bromine, although with m u c h more difficulty t h a n the m e t h y l a t c d double b o n d [26]. The latter results in the f o r m a t i o n of tribromide. CONCLUSIONS
(1) A s t u d y was made of the s t r u c t u r e of p r o d u c t s of b r o m i n a t i o n of cisand trans-polyisoprenes a n d squalene in a solution of benzene and chloroform at various stages of the reaction using I R s p e c t r o s c o p y and high resolution NMR,. (2) Processes of s u b s t i t u t i o n t a k i n g place r a p i d l y a n d simultaneously with a d d i t i o n to the double b o n d result in the t b r m a t i o n of e x o m e t h y l e n e groups a n d intramoleetflar cyclic structm'es. (3) The sh)w a d d i t i o n of bromine to vinylidene double bonds results in the f o r m a t i o n of the t r i b r o m i d e CaHTBr a. (4) A difference was observed in the s t r u c t u r e of p r o d u c t s of b r o m i n a t i o n of t:is- ~md trans-polyisoprenes a n d a s y s t e m is I)roposcd to rel)rcscnt the rearetions t a k i n g place dm'ing b r o m i n a i i ( m of p(~lyisel)rene.
Tra~sl(Itt~d by E. SEMERE R~:FI:R£NCI:S 1. W. K. LEWIS, W. H. McADAMS, lt~dustr. "rod Engng. Cicero. 12: 673, 1920 2. l-I. L. FISHER, G. GRAY and R. MELTING, h~dustr. ~md Engng. Ckem. 13: 1031, 1921 3. (L O. WILLITS, M. Z. SWAIN and C. L. 0GG, gubb¢,r. ('h(~m. ~md Technol. 20: 320, 1947
4. W. J. GOWANS and F. E. CLARK, l{ubber Chem. ~md Teclmo]. 25: 961, 1952 5. F. J. MAFFEL, M. OUTA, Rubber. Chem. and Technol. 23: 457, 1950 6. J. W. MEEKS, R. V. CROOK, C. E. PARDO and F. E. CLARK, A~lalyt.. Chem. 25: 1536, 195"1 7. G. T. DAROVSKIKH and G. A. TROFIMOV, Kauchuk i rezma, ~No. l 1, 4S, 1963 8. T. J. B A K E R , L. G. LAYKO, R. D. STUBBLEFIELD m~d R . F . ANDERSON, An~lyt. Biochem. 2: 287, 1961 9. K. R. MIDDLETON, Anal.~ st 88: 368, 1963 10. R. T. MORRISEY, Industr. and Engng. Chem. 47: 1562, 1955 I I. C. PINAZZI, G. GUENIFFEY and J. BROSSAS, Compt. rend. 258: 4982, 1964 12. G. F. BLOOMFIELD, J. Soc. Chem. I~tdustr. transacv. 64: 274, 1945 l'k ]-I. STAUDINGER and I-I. STAUDINGER, Rubber ('h¢ml. and Technol. I7: 15, 1944 14. N. A. PLATE, TRAN KI-I'EY, V. P. SHIBAYEV and V. A. KARGIN, Vysok(mlol. soy¢~d. 7: 152,% 1965 (Tr~n.~lat~,(t in Polym~,r S(d. [T.S.S.I£. 7: 9. 1683, 1965)
1080
V . V . GUZEYEV et al.
15. I. A. TUTOItSKII, L. V. SOKOLOVA and B. A. DOGADKIN, Uchenye zapiski, No. 2, 33, 1961 16. G. A. CHELISHEVA, G. M. CHEBYSHEVA and G. P. SHCHERBACHEV, Kauchuk i rezina, No. 2, 33, 1961 17. G. SALOMON, A. Chr. VAN DER SCHEE, J. A. A. KETELAAR and B. J. VAN EYK, Disc. Faraday See., :No. 9, 291, 1950 18. L. BELLAMY, Infrakrasnye spektry slozhnykh molekul (IR Spectra of Complex Molecules). Izd. inostr, lit., 1963 19. Yu. A. PENTIN, E. V. MOItOZOV and Z. SHARIPOV, Vestn. MGU, No. 2, 23, 1966 20. I. A. TUTOItSKII, I. Ya. SLONIM, E. G. BOIKACHEVA, O. A. MOCHALOVA, L. V. SOKOLOVA and B. A. DOGADKIN, Vysokomol. soyed. A10: 592, 1968 (Translated in Polymer Sci. U.S.S.R. 10: 3, 692, 1968) 21. M. STOLKA, J. VODEHNAL and J. K(iSSLER, J. :Polymer Sci. A2: 3987, 1964 22. M. V. EVANS, G. N. C. HIGGINS, D. F. LEE and W. F. WATSON, J. Appl. :Polymer Sci. 4: 367, 1960 23. I. A. TUTORSKII, L. V. SOKOLOVA and B. A. DOGADKIN, Kolloidn. zh. 32: 590, 1970 24. L. ANDREWS and It. KIFER, Molekulyarnye kompleksy v organicheskoi khimii (Molecular Complexes in Organic Chemistry). Izd. "Mir", 1967 25. K. D. NENITSESKU, Organicheskaya khimiya (Organic Chemistry). Vol. 1, p. 389, Izd. inostr, lit., 1962 26. B. E. SWEDLUND and P. W. ItOBEItTSON, J. Chem. See., 630, 1947
THERMODYNAMICS OF THE DEFORMATION OF PLASTICIZED POLYVINYLCHLORIDE FILLED WITH AEROSIL AND KAOLIN* V. V. GUZEYEV, ZH. I. SHKALENKO, YU. M. MALINSKII a n d V. A. KARGIN (dec.) (Received 26 December 1969)
IT tlAS been r e p o r t e d [1] t h a t the addition of finely dispersed silica aerosil to plasticized p o l y v i n y l c h l o r i d e composition m a r k e d l y alters certain properties of the polymer. A n a t t e m p t was m a d e in this s t u d y to examine high-elastic d e f o r m a t i o n of plasticized polyvinylchloride filled with aerosil a n d kaolin, which differ in chemical composition, degree of dispersion a n d o t h e r properties. Owing to these differences it can be expected t h a t aerosil a n d kaolin will h a v e different effects on the elast i c i t y of filled plasticized polyvinylchloride (PVC). EXPERIMENTALt
The samples contained 100 parts by weight S-75 PVC (molecular weight 100,000), 50 parts by weight didecylphthalate plasticizer, 8 parts by weight dibasic lead phthalate m~d dibasic lead stearate stabilizers and 0.3 parts by weight diphenylolpropaae aatioxidant. * Vysokomol. soyed. A13: No. 4, 958-965, 1971. t L. M. Marty~lova, N. P. Urtmir~tseva and L. V. Medvedeva took part i~ the experinl(~tlts.