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Kinetics of interaction of m-chlorophenyl isocyanate with glycols
KINETICS OF INTERACTION OF m-CHLOROPHENYL ISOCYANATE WITH GLYCOLS V. A. GRIGOR'EVA, S. M. BATURIN a n d S. G. E~TELIS Institute of Chemical Physics, U.S.S.R. Academy ¢~f Sciences (Received 13 November 1970)
THE p r o b l e m of t h e r e a c t i v i t y of c o m p o u n d s containing h y d r o x y l , which are used in u r e t h a n e f o r m a t i o n , has been ex~ensively discussed in t h e l i t e r a t u r e [1, 2]. This p r o b l e m is p a r t i c u l a r l y i m p o r t a n t w h e n e x a m i n i n g t h e kinetics of threed i m e n s i o n a l p o l y m e r i z a t i o n during t h e synthesis of crosslinked p o l y u r e t h a n e s [3]. M a n y effects are difficult to e x p l a i n e x c e p t b y e m p l o y i n g concepts of v a r y i n g r e a c t i v i t i e s o f c o m p o u n d s containing h y d r o x y l in t h e s y s t e m (polyester diol, triol, diol) a n d concerning a whole n u m b e r of processes a c c o m p a n y i n g t h e f o r m a t i o n o f a t h r e e - d i m e n s i o n a l s t r u c t u r e of p o l y e s t e r u r e t h a n e . T h i s p a p e r deals w i t h t h e kinetics of t h e m o d e l r e a c t i o n of m - c h l o r o p h e n y l i s o c y a n a t e (CPI) w i t h p o l y e s t e r diol, t r i m e t h y l o l p r o p a n e a n d 1,4-butanediol a n d explains t h e i r r e a c t i v i t i e s w h e n m i x e d w i t h each other. T h e possibility is e x a m i n e d of b a l a n c i n g t h e v a r y i n g reactivities of m a t e r i a l s containing h y d r o x y l b y a c a t a lyst, of w h i c h t h e m e c h a n i s m of action is well known. EXPERIMENTAL A tetrahydrofuran-propylene oxide (THF-PO) copolymer was prepared by cationic copolymerization by methods previously described [4]. To eliminate traces of boron trifluoride, a copolymer solution in acetone was repeatedly washed with water. The copolymer was dried as a thin film on a plate-like column at 60°/1.5 × 10 -8 mm. Moisture content in the copolymer specimens was less than 0-01 wt. ~ (control was effected by the Fischer method). The molecular weight of the eopolymer determined from an analysis of hydroxyl end groups was 18204-30 in terms of bifunetionality. Butane-l,4-diol was distilled i n vacuo and the fraction at 85°/0.1 mm taken. OH group content corresponded to the calculated value. Water content was less than 0.01 wt. %. Trimethylo] propane (TM-P) (chemically pure) was not specially purified. TMP was dried in vacuum at 20°. Water content of TMP was under 0.03 wt. %. CPI was distilled in vacuum and a fraction taken at 35°/0.08 mm. Isocyanate was stored in sealed ampoules i n vacuo. Tin-dibutyl-dilaurate of m.p. 29 ° was used as catalyst. Kinetics of reaction of CPI with components containing hydroxyl were studied in a Calve microcalorimeter at 28 °. * Vysokomol. soyed. A14: No. 6, 1345-1349, 1972. 1507
1508
V.A.
GRIOOR'EVA et al.
RESULTS AND DISCUSSION
Kinetics and reactivities of materials containing hydroxyl were studied during interaction with CPI in a copolymer-diol mixture and in a model polymer solvent with an equimolecular ratio of functional groups. A dibutyl urethane copolymer (DBUC) was used as model polymer medium: a T H F - P O copolymer was used (/~rn~1820), of which the hydroxyl end groups were blocked b y reaction with n-butyl isocyanate. Before discussing the results it should be noted that the kinetics of the interaction oi CPI with the T H F - P O block copolymer follows a second order equation with one rate constant from the beginning to the end of the reaction. Transition to a model polymer medium does not involve considerable change in the kinetics of the reaction of CPI with the copolymer, TMP and butane-l,4-diol, a second order rule applies strictly in every case up to high degrees of conversion. The constancy of the rate constant observed during the reaction of CPI with TMP during one experiment proves that all hydroxyl groups of triol have similar reactivities. The rate constants of the reaction of CPI with copolymer diol, triol and butane diol in DBUC medium are shown in Table 1, which indicates that under the conditions studied rate constants of the reaction of butane-1,4-diol, TMP and the copolymer show a 7 : 2 : 1 ratio.
T & B L E 1. R E L A T I V E R E A C T I V I T I E S OF COMPONENTS C O N T A I N I N G H Y D R O X Y L WITH m-CHLOROPHENYLISOCYANATE IN A DIBUTYL URETHANE COPOLYMER MEDIUM
Polyol THF-PO copolymer TMP Butane- 1,4-diol.
AT
28 ° .
COH,
eNCO,
kO" 1 0 a,
g-equiv/l,
g-equiv/1.
1./g.equiv.see
0.488
0-461 0.454 0.401
0.922 2.110 6-438
0.452 0.476
*
k°/kQ°P
* kcop--rate c o ~ t a n t of the reaction of the copolymer with CPL
A study was made of the reaction of CPI with the copolymer, TMP and butane1,4-diol in the bulk of the copolymer. However, when the reaction was carried out in the bulk of the copolymer several experimental and theoretical difficulties arise in determining reactivity of materials containing hydroxyl. The presence of two types of reaction group of the same nature reacting simultaneously with a third component gives the pattern of a second order parallel reaction. The kinetic curve rectified in ordinary co-ordinates of a second o r d e r reaction is complex. Two sections are observed on the rectified kinetic curves.
Kinetics of interaction of m-chlorophenyl isocyanate with glycols
1509
In this case rate constants of the reaction of CPI with binary mixtures of the copolymer and diol or copolymer and triol were determined from the initial reaction rate. The following expression gives the initial reaction rate: w0= ko[NCO] [OH] ov= kl [NCO] [OH]cop+ k=dl°~[NCO] [OH]d~ol,
(1)
where [OH]ov, [OH]~op and [OH]dieI are the concentrations of hydroxyl groups, (overall concentration, concentrations of the copolymer and diol, respectively), g-equiv./1.; ko, kl and k~i°1 are rate constants (observed during the reaction of isocyanatc with the copolymer and isocyanate with diol, respectively), 1./g-equiv × × see. Expressing the concentration of OH groups of the copolymer by [0Hie v and [ O H ] d i o l , w e obtain [OH]~op=[OH]o~--[OH]diol
(2)
Substituting in eqn. (1)eqn. (2) and separating all to [OH]ov, [NCO], we obtain /c0 = kl ~-(k~°~--/c~)[OH]d~off[OH]ov
(3)
There is also a similar expression for the copolymer-triol mixture. Ratio (3) is confirmed b y the linear dependence of k o on the ratio of initial concentration of OH groups of diol and triol to the overall concentration of O H groups in a mixture in the concentration range of diol or triol (Fig. 1). The accuracy of this method of determining constants was confirmed b y computer calculations. Constants derived from eqn. (3) were used to construct kinetic curves from a system of parallel reactions kz R N C O ~- H e ~ R ' ~ O H - - - - - * u r e t h a n e
RNCO ~ He ~ R" N OH-- -- -,urethane \
ko values determined experimentally and from the kinetic curves show satisfactory agreement (Fig. 1.). Constants thus derived, retain the order kai°l> 2 kc ~lOa,l./g-equ/v.sec lz/ 1
2
/ I
I
0.2
I
I
04/
FIG. 1. D e p e n d e n c e o f k0 o n t h e r a t i o o f i n i t i a l c o n c e n t r a t i o n o f O H g r o u p s o f diol to the overall concentration of OH groups in the mixture: /---experimental, 2calculated values.
V . A . GRIOOR'EVAet al.
1510
>ktrl°l>k ~°l is 16 times as high as k I a n d kz is 8 times as high as kl. This 2 1 a n d k2 difference in r e a c t i v i t y of c o m p o n e n t s containing h y d r o x y l on changing f r o m u r e t h a n e m e d i u m (DBUC) t o p o l y m e r is, a p p a r e n t l y , due to t h e specific effect o f t h e m e d i u m w h i c h is a c c o m p a n i e d b y different processes o f complex formation. Difference in reaetivities o f c o m p o n e n t s containing h y d r o x y l results in a n irregular n e t w o r k during t h e synthesis o f crosslinked polyester urethanes, which causes d e t e r i o r a t i o n o f elastic properties. There are m e t h o d s of p r e p a r i n g elastomers w i t h u n i f o r m crosslinks [3]. A c a t a l y s t m a y be used to balance t h e difference in t h e reactivities of c o m p o u n d s containing h y d r o x y l . The mechanism of action of organic tin catalysts has been very extensively studied [5, 7]. It was shown for these systems that the catalyst-alcohol complex is the active intermediate complex responsible for catalysis. The kinetic system of the catalytic reaction can be presented as: K
k,
k,
R'OH+cat~X,;
X,-}- RNCO ~X,-}- cat.; X, ~urethane /cI An intermediate catalyst-alcohol complex is formed rapidly in the first stage with equilibrium constant/f, followed by the formation as a result of interaction of XI with isocyanate of complex Xs which undergoes monomolecular conversion to urethane as final product; the rate constant obtained in the aleohol-isoeyanate reaction should depend on the strength o f the alcohol-catalyst complex. Data indicate [5] that both a significant increase and a considerable weakening in the strength of the complex will affect the reduction of the reaction rate constant. I t may therefore be assumed that an increase in the basicity of alcohol should increase the strength of the alcohol-catalyst complex. Because of this, tin dibutyl dilaurate accelerates the reaction of n-butanol with phenylisocyauate to a greater extent than see-butanol. According to a former study [6], for an uncatalysed reaction the rate constant of the reaction of n-butanol with phenylisocyanate is 3 times as high as the reaction rate constant of sec-butanol, while in the presence of 10-~ mole/1, tin dibutyl dilaurate the difference becomes 12 times greater. There is no information at all in the literature concerning the simultaneous presence in the system of hydroxyl compounds of different basicities. In this case the catalyst should be used for the formation of a stronger, although less active complex of greater basicity in respect of hydroxyl. It may consequently be expected that an uncatalysed reaction at a lower rate will be accelerated by catalyst to a higher extent than that occuring at a higher rate. TABLE
2. I~EACTIO!W OF /-CHLOI%OPHENYLISOCYANATE TIN
Material containing hydroxyl THF-PO
Medium DBUC
Butane- 1,4-diol
THF-PO
THF-PO copolymer
WITH POLYOLS
DIBUTY-L DILAURATE
IN THE PRESENCE
OF
AT 28 °
coil, g-equiv/1,
CNco, g-equiv/1,
0.488 0.493 0.488 0-486 0.486 0.173 0.182 0.169 0.970
0.461 0.469 0.502 0.441 0.482 0.166 0.156 0.148 0.923
CcatX 106, mole/l. 0.209 8.528 12,770 17,190 1.926 14.440
ko X I0', 1./g-equiv- sec 0.922 0.958 0"831 0.992 O.885 7.230 6.830 6.720 0"145
Kinetics of interaction of m-chlorophenyl isocyanate with glycols
1511
When studying the catalytic reaction of polyols with isoeyanate in a urethane copolymer medium the rate constant of the catalytic reaction is independent of catalyst concentration within a wide range and remains equal to the rate constant of the uneatalysed reaction (Table 2.). This can be explained as follows. The concentration of urethane groups in DBUC is 0.98 mole/1. Under these conditions the entire catalyst is evidently combined in a fairly strong complex with the
k. / 03,L/g-ecuiv.sec !
o
!
2
3
q
b
0
~"v"-~m-"7"
1
3
i
L
5
i
,
~
i
7 5 9 Ccat ,10, rno/e/L
FIG. 2. Dependence of rate constants of catalytic reactions on catalyst concentration in the binary mixtures: a - - t r i m e t h y l o l propane (1) and T H F - P O copolymer (2); b - - b u t a n e - l , 4 - d i o l (1) and T H F - P O copolymer (2) (in the Figure a 10; 20; 30; 40 should be read along the abscissa axis).
urethane group and does not accelerate the reaction between the isoeyanate and hydroxyl groups. Therefore,/c o in the urethane copolymer medium is independent of catalyst concentration in the range studied, whereas for the reaction of CPI with a T H F - P O copolymer catalysis occurs in the bulk of the copolymer. The catalytic rate constant is 71.2/mole ~- see. The catalytic reaction of CPI with a T H F - P O copolymer, TMP and butane1,4-diol has been studied in more detail in the bulk of the copolymer. The kinetics of the catalytic reaction of binary mixture of butane-l,4-diol-THF-PO copolymer with CPI were examined in the concentration range of the catalyst of 2-2)< 10-5-9.3× 10 -5 mole/1, and of a binary mixture of trimethylolpropaneT H F - P O copolymer with CPI, in the concentration range of the catalyst of 9 × 10-6-4.3 × 10 -4 mole/1. From eqn. (3) values of ]c1, ksdl°l and k tn°x were calculated for all catalyst concentrations. Results are shown in Fig. 2. The Figure indicates that on increasing catalyst concentration, k dl°~ and/~loi rapidly reach certain limiting values and then remain constant, while/~1 increases with higher values of teat. I t is evident that with a certain catalyst concentration/~1 will be equal to /c~°l and /~iol and inversion m a y even take place in the rates, when
/¢1>/~ °l ,/~1>k2.
|512
A. YE. CHUCHII~" 8~ ~ .
CONCLUSIONS
(I) A study was made of the relative reactivities of butane-l,4-diol, trimethylolpropane and a copotymer of tetrahydrofuran and propylene oxide (THF-PO) in the reaction with m-chlorophenyl isocyanate (CPI) in dibutyl urethane eopolymer (DBUC) medium and in the solid copolymer. (2) I t was shown t h a t when the reaction takes place in DBUC the rate constant observed is independent of catalyst concentration in the range studied. (3) When studying the catalytic reaction of CPI with binary mixtures of T H F - P O copolymer-hutane-l,4-diol and T H F - P O copolymer-trimethylol propane it was possible to balance the varying reactivities of polyols by using a tin dibutyl dilaurate catalyst. Tra~bs~y~d by E. SEM~ERE
REFERENCES
1. Dzh. Kh. SAUNDERS and K. K. FRISH, Khimiya poliuretanov (Chemistry of Polyurethanes). Khimiya, 1968 2. K. J. RAUTERKUS, H. G. SCHIMMELand W. KERN, Makromolok. Chem. 50: 166, 1961 3. S. L. A_~ELROOD, C. W. HAMILTON and K. C. FRISCH, Industr. and Engng. Chem. 53: 889, 1961 4. A. I. KUZAYEV, G. N. KOMRATOV, G. V. KOROVINA, G. A. MIRONTSEVA and S. G. ENTELIS, Vysokomol. soyed. All: 443, 1969 (Translated in Polymer Sei. U.S.S.R. 11: 2, 502, 1969) 5. O. V. NESTEROV, Dissertation, 1966 6. L. RAND, B. THTER, S. L. REEGEN and K. C. FRISCH, J. Appl. Polymer Sci. 9: 1787, 1965 7. V. B. ZABROD1N, O. V. NESTEROV and S. G. ENTELIS, Kinotika i kataliz, 10: 663, 1969
OXIDATION
OF POLYPHENYLENE
TOLUYLENE
ETHERS*
A. YE. CHUCHII~',V. V. ROZHKOV, N. P. GASH~IKOVA, 1K. B. FROMBERG an4 V. S. ~LFAI~AS'EVA V. I. Lenin All-Union Eleetrotechnical Institute (Received 13 November 1970)
POLYMER and oligomer peroxides and hydroperoxides, which contain active oxygen at the ends of, and along, the molecular chain, may be used as initiators Of graft block copolymerization and enable the properties of polymers obtained by radical polymerization to be modified considerably * Vysokomol. soyed. AI4: No. 6, 1350-1359, 1972.
THE p r o b l e m of t h e r e a c t i v i t y of c o m p o u n d s containing h y d r o x y l , which are used in u r e t h a n e f o r m a t i o n , has been ex~ensively discussed in t h e l i t e r a t u r e [1, 2]. This p r o b l e m is p a r t i c u l a r l y i m p o r t a n t w h e n e x a m i n i n g t h e kinetics of threed i m e n s i o n a l p o l y m e r i z a t i o n during t h e synthesis of crosslinked p o l y u r e t h a n e s [3]. M a n y effects are difficult to e x p l a i n e x c e p t b y e m p l o y i n g concepts of v a r y i n g r e a c t i v i t i e s o f c o m p o u n d s containing h y d r o x y l in t h e s y s t e m (polyester diol, triol, diol) a n d concerning a whole n u m b e r of processes a c c o m p a n y i n g t h e f o r m a t i o n o f a t h r e e - d i m e n s i o n a l s t r u c t u r e of p o l y e s t e r u r e t h a n e . T h i s p a p e r deals w i t h t h e kinetics of t h e m o d e l r e a c t i o n of m - c h l o r o p h e n y l i s o c y a n a t e (CPI) w i t h p o l y e s t e r diol, t r i m e t h y l o l p r o p a n e a n d 1,4-butanediol a n d explains t h e i r r e a c t i v i t i e s w h e n m i x e d w i t h each other. T h e possibility is e x a m i n e d of b a l a n c i n g t h e v a r y i n g reactivities of m a t e r i a l s containing h y d r o x y l b y a c a t a lyst, of w h i c h t h e m e c h a n i s m of action is well known. EXPERIMENTAL A tetrahydrofuran-propylene oxide (THF-PO) copolymer was prepared by cationic copolymerization by methods previously described [4]. To eliminate traces of boron trifluoride, a copolymer solution in acetone was repeatedly washed with water. The copolymer was dried as a thin film on a plate-like column at 60°/1.5 × 10 -8 mm. Moisture content in the copolymer specimens was less than 0-01 wt. ~ (control was effected by the Fischer method). The molecular weight of the eopolymer determined from an analysis of hydroxyl end groups was 18204-30 in terms of bifunetionality. Butane-l,4-diol was distilled i n vacuo and the fraction at 85°/0.1 mm taken. OH group content corresponded to the calculated value. Water content was less than 0.01 wt. %. Trimethylo] propane (TM-P) (chemically pure) was not specially purified. TMP was dried in vacuum at 20°. Water content of TMP was under 0.03 wt. %. CPI was distilled in vacuum and a fraction taken at 35°/0.08 mm. Isocyanate was stored in sealed ampoules i n vacuo. Tin-dibutyl-dilaurate of m.p. 29 ° was used as catalyst. Kinetics of reaction of CPI with components containing hydroxyl were studied in a Calve microcalorimeter at 28 °. * Vysokomol. soyed. A14: No. 6, 1345-1349, 1972. 1507
1508
V.A.
GRIOOR'EVA et al.
RESULTS AND DISCUSSION
Kinetics and reactivities of materials containing hydroxyl were studied during interaction with CPI in a copolymer-diol mixture and in a model polymer solvent with an equimolecular ratio of functional groups. A dibutyl urethane copolymer (DBUC) was used as model polymer medium: a T H F - P O copolymer was used (/~rn~1820), of which the hydroxyl end groups were blocked b y reaction with n-butyl isocyanate. Before discussing the results it should be noted that the kinetics of the interaction oi CPI with the T H F - P O block copolymer follows a second order equation with one rate constant from the beginning to the end of the reaction. Transition to a model polymer medium does not involve considerable change in the kinetics of the reaction of CPI with the copolymer, TMP and butane-l,4-diol, a second order rule applies strictly in every case up to high degrees of conversion. The constancy of the rate constant observed during the reaction of CPI with TMP during one experiment proves that all hydroxyl groups of triol have similar reactivities. The rate constants of the reaction of CPI with copolymer diol, triol and butane diol in DBUC medium are shown in Table 1, which indicates that under the conditions studied rate constants of the reaction of butane-1,4-diol, TMP and the copolymer show a 7 : 2 : 1 ratio.
T & B L E 1. R E L A T I V E R E A C T I V I T I E S OF COMPONENTS C O N T A I N I N G H Y D R O X Y L WITH m-CHLOROPHENYLISOCYANATE IN A DIBUTYL URETHANE COPOLYMER MEDIUM
Polyol THF-PO copolymer TMP Butane- 1,4-diol.
AT
28 ° .
COH,
eNCO,
kO" 1 0 a,
g-equiv/l,
g-equiv/1.
1./g.equiv.see
0.488
0-461 0.454 0.401
0.922 2.110 6-438
0.452 0.476
*
k°/kQ°P
* kcop--rate c o ~ t a n t of the reaction of the copolymer with CPL
A study was made of the reaction of CPI with the copolymer, TMP and butane1,4-diol in the bulk of the copolymer. However, when the reaction was carried out in the bulk of the copolymer several experimental and theoretical difficulties arise in determining reactivity of materials containing hydroxyl. The presence of two types of reaction group of the same nature reacting simultaneously with a third component gives the pattern of a second order parallel reaction. The kinetic curve rectified in ordinary co-ordinates of a second o r d e r reaction is complex. Two sections are observed on the rectified kinetic curves.
Kinetics of interaction of m-chlorophenyl isocyanate with glycols
1509
In this case rate constants of the reaction of CPI with binary mixtures of the copolymer and diol or copolymer and triol were determined from the initial reaction rate. The following expression gives the initial reaction rate: w0= ko[NCO] [OH] ov= kl [NCO] [OH]cop+ k=dl°~[NCO] [OH]d~ol,
(1)
where [OH]ov, [OH]~op and [OH]dieI are the concentrations of hydroxyl groups, (overall concentration, concentrations of the copolymer and diol, respectively), g-equiv./1.; ko, kl and k~i°1 are rate constants (observed during the reaction of isocyanatc with the copolymer and isocyanate with diol, respectively), 1./g-equiv × × see. Expressing the concentration of OH groups of the copolymer by [0Hie v and [ O H ] d i o l , w e obtain [OH]~op=[OH]o~--[OH]diol
(2)
Substituting in eqn. (1)eqn. (2) and separating all to [OH]ov, [NCO], we obtain /c0 = kl ~-(k~°~--/c~)[OH]d~off[OH]ov
(3)
There is also a similar expression for the copolymer-triol mixture. Ratio (3) is confirmed b y the linear dependence of k o on the ratio of initial concentration of OH groups of diol and triol to the overall concentration of O H groups in a mixture in the concentration range of diol or triol (Fig. 1). The accuracy of this method of determining constants was confirmed b y computer calculations. Constants derived from eqn. (3) were used to construct kinetic curves from a system of parallel reactions kz R N C O ~- H e ~ R ' ~ O H - - - - - * u r e t h a n e
RNCO ~ He ~ R" N OH-- -- -,urethane \
ko values determined experimentally and from the kinetic curves show satisfactory agreement (Fig. 1.). Constants thus derived, retain the order kai°l> 2 kc ~lOa,l./g-equ/v.sec lz/ 1
2
/ I
I
0.2
I
I
04/
FIG. 1. D e p e n d e n c e o f k0 o n t h e r a t i o o f i n i t i a l c o n c e n t r a t i o n o f O H g r o u p s o f diol to the overall concentration of OH groups in the mixture: /---experimental, 2calculated values.
V . A . GRIOOR'EVAet al.
1510
>ktrl°l>k ~°l is 16 times as high as k I a n d kz is 8 times as high as kl. This 2 1 a n d k2 difference in r e a c t i v i t y of c o m p o n e n t s containing h y d r o x y l on changing f r o m u r e t h a n e m e d i u m (DBUC) t o p o l y m e r is, a p p a r e n t l y , due to t h e specific effect o f t h e m e d i u m w h i c h is a c c o m p a n i e d b y different processes o f complex formation. Difference in reaetivities o f c o m p o n e n t s containing h y d r o x y l results in a n irregular n e t w o r k during t h e synthesis o f crosslinked polyester urethanes, which causes d e t e r i o r a t i o n o f elastic properties. There are m e t h o d s of p r e p a r i n g elastomers w i t h u n i f o r m crosslinks [3]. A c a t a l y s t m a y be used to balance t h e difference in t h e reactivities of c o m p o u n d s containing h y d r o x y l . The mechanism of action of organic tin catalysts has been very extensively studied [5, 7]. It was shown for these systems that the catalyst-alcohol complex is the active intermediate complex responsible for catalysis. The kinetic system of the catalytic reaction can be presented as: K
k,
k,
R'OH+cat~X,;
X,-}- RNCO ~X,-}- cat.; X, ~urethane /cI An intermediate catalyst-alcohol complex is formed rapidly in the first stage with equilibrium constant/f, followed by the formation as a result of interaction of XI with isocyanate of complex Xs which undergoes monomolecular conversion to urethane as final product; the rate constant obtained in the aleohol-isoeyanate reaction should depend on the strength o f the alcohol-catalyst complex. Data indicate [5] that both a significant increase and a considerable weakening in the strength of the complex will affect the reduction of the reaction rate constant. I t may therefore be assumed that an increase in the basicity of alcohol should increase the strength of the alcohol-catalyst complex. Because of this, tin dibutyl dilaurate accelerates the reaction of n-butanol with phenylisocyauate to a greater extent than see-butanol. According to a former study [6], for an uncatalysed reaction the rate constant of the reaction of n-butanol with phenylisocyanate is 3 times as high as the reaction rate constant of sec-butanol, while in the presence of 10-~ mole/1, tin dibutyl dilaurate the difference becomes 12 times greater. There is no information at all in the literature concerning the simultaneous presence in the system of hydroxyl compounds of different basicities. In this case the catalyst should be used for the formation of a stronger, although less active complex of greater basicity in respect of hydroxyl. It may consequently be expected that an uncatalysed reaction at a lower rate will be accelerated by catalyst to a higher extent than that occuring at a higher rate. TABLE
2. I~EACTIO!W OF /-CHLOI%OPHENYLISOCYANATE TIN
Material containing hydroxyl THF-PO
Medium DBUC
Butane- 1,4-diol
THF-PO
THF-PO copolymer
WITH POLYOLS
DIBUTY-L DILAURATE
IN THE PRESENCE
OF
AT 28 °
coil, g-equiv/1,
CNco, g-equiv/1,
0.488 0.493 0.488 0-486 0.486 0.173 0.182 0.169 0.970
0.461 0.469 0.502 0.441 0.482 0.166 0.156 0.148 0.923
CcatX 106, mole/l. 0.209 8.528 12,770 17,190 1.926 14.440
ko X I0', 1./g-equiv- sec 0.922 0.958 0"831 0.992 O.885 7.230 6.830 6.720 0"145
Kinetics of interaction of m-chlorophenyl isocyanate with glycols
1511
When studying the catalytic reaction of polyols with isoeyanate in a urethane copolymer medium the rate constant of the catalytic reaction is independent of catalyst concentration within a wide range and remains equal to the rate constant of the uneatalysed reaction (Table 2.). This can be explained as follows. The concentration of urethane groups in DBUC is 0.98 mole/1. Under these conditions the entire catalyst is evidently combined in a fairly strong complex with the
k. / 03,L/g-ecuiv.sec !
o
!
2
3
q
b
0
~"v"-~m-"7"
1
3
i
L
5
i
,
~
i
7 5 9 Ccat ,10, rno/e/L
FIG. 2. Dependence of rate constants of catalytic reactions on catalyst concentration in the binary mixtures: a - - t r i m e t h y l o l propane (1) and T H F - P O copolymer (2); b - - b u t a n e - l , 4 - d i o l (1) and T H F - P O copolymer (2) (in the Figure a 10; 20; 30; 40 should be read along the abscissa axis).
urethane group and does not accelerate the reaction between the isoeyanate and hydroxyl groups. Therefore,/c o in the urethane copolymer medium is independent of catalyst concentration in the range studied, whereas for the reaction of CPI with a T H F - P O copolymer catalysis occurs in the bulk of the copolymer. The catalytic rate constant is 71.2/mole ~- see. The catalytic reaction of CPI with a T H F - P O copolymer, TMP and butane1,4-diol has been studied in more detail in the bulk of the copolymer. The kinetics of the catalytic reaction of binary mixture of butane-l,4-diol-THF-PO copolymer with CPI were examined in the concentration range of the catalyst of 2-2)< 10-5-9.3× 10 -5 mole/1, and of a binary mixture of trimethylolpropaneT H F - P O copolymer with CPI, in the concentration range of the catalyst of 9 × 10-6-4.3 × 10 -4 mole/1. From eqn. (3) values of ]c1, ksdl°l and k tn°x were calculated for all catalyst concentrations. Results are shown in Fig. 2. The Figure indicates that on increasing catalyst concentration, k dl°~ and/~loi rapidly reach certain limiting values and then remain constant, while/~1 increases with higher values of teat. I t is evident that with a certain catalyst concentration/~1 will be equal to /c~°l and /~iol and inversion m a y even take place in the rates, when
/¢1>/~ °l ,/~1>k2.
|512
A. YE. CHUCHII~" 8~ ~ .
CONCLUSIONS
(I) A study was made of the relative reactivities of butane-l,4-diol, trimethylolpropane and a copotymer of tetrahydrofuran and propylene oxide (THF-PO) in the reaction with m-chlorophenyl isocyanate (CPI) in dibutyl urethane eopolymer (DBUC) medium and in the solid copolymer. (2) I t was shown t h a t when the reaction takes place in DBUC the rate constant observed is independent of catalyst concentration in the range studied. (3) When studying the catalytic reaction of CPI with binary mixtures of T H F - P O copolymer-hutane-l,4-diol and T H F - P O copolymer-trimethylol propane it was possible to balance the varying reactivities of polyols by using a tin dibutyl dilaurate catalyst. Tra~bs~y~d by E. SEM~ERE
REFERENCES
1. Dzh. Kh. SAUNDERS and K. K. FRISH, Khimiya poliuretanov (Chemistry of Polyurethanes). Khimiya, 1968 2. K. J. RAUTERKUS, H. G. SCHIMMELand W. KERN, Makromolok. Chem. 50: 166, 1961 3. S. L. A_~ELROOD, C. W. HAMILTON and K. C. FRISCH, Industr. and Engng. Chem. 53: 889, 1961 4. A. I. KUZAYEV, G. N. KOMRATOV, G. V. KOROVINA, G. A. MIRONTSEVA and S. G. ENTELIS, Vysokomol. soyed. All: 443, 1969 (Translated in Polymer Sei. U.S.S.R. 11: 2, 502, 1969) 5. O. V. NESTEROV, Dissertation, 1966 6. L. RAND, B. THTER, S. L. REEGEN and K. C. FRISCH, J. Appl. Polymer Sci. 9: 1787, 1965 7. V. B. ZABROD1N, O. V. NESTEROV and S. G. ENTELIS, Kinotika i kataliz, 10: 663, 1969
OXIDATION
OF POLYPHENYLENE
TOLUYLENE
ETHERS*
A. YE. CHUCHII~',V. V. ROZHKOV, N. P. GASH~IKOVA, 1K. B. FROMBERG an4 V. S. ~LFAI~AS'EVA V. I. Lenin All-Union Eleetrotechnical Institute (Received 13 November 1970)
POLYMER and oligomer peroxides and hydroperoxides, which contain active oxygen at the ends of, and along, the molecular chain, may be used as initiators Of graft block copolymerization and enable the properties of polymers obtained by radical polymerization to be modified considerably * Vysokomol. soyed. AI4: No. 6, 1350-1359, 1972.