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Reaction of Diamines with diisocyanates—III. Reaction of aromatic diamines with diisocyanates
REACTION OF DIAMINES WITH DHSOCYANATES--HI. REACTION OF AROMATIC DIAMINES WITH DHSOCYANATES* O. YA. FEDOTOVA and A. G. GROZDOV Moscow Chemico-Technological Institute (Received 13 November 1961)
POLYURETHANES are known to be produced b y the interaction of diamines with diisocyanates. In this process the solutions of the initial materials merge t o form a common solvent, and the reaction occurs at a rate which in some cases is very close to that of ionic reactions [1]. The rate of this reaction depends o n the reactive capacity of the diamines and diisocyanates and, consequently, ~)n their chemical structure. The reactive capacity of the diamines is determined b y the extent of their basicity, which falls as one passes from the aliphatic to ~he aromatic series. In its turn, the reactive capacity of aromatic diamines depends on the nature o f the amino groups, the presence of substitutes in the nucleus and on their influence. Thus Fedotova and Skripchenko et al. [2], have shown that the primary 4iamines of the series 4,4' diamino diphenyl methane have greater reactive capacity than the diamines of the series 4,4' diamino ditolyl methane substituted in the series, the first being more active than the second. The reactive capacity ~)f the secondary diamines of these series falls as the number of carbon atoms :in the substituent rises in the presence of nitrogen [2]. In its turn the reactive capacity of the diisocyanates falls as one passes from aromatic to aliphatic series [2]. The existence and structure of the bridge between t h e nuclei also affects the reactive capacity of the binuclear aromatic diamines. F o r instance, benzidiene has a greater reactive capacity than diamino diphenyl methane, while diamino diphenyl sulphone has very low activity in the reaction with diisocyanates. It has very weak basic properties due to the presence of the ~lectrophile group --S02--, which repulses the electron cloud of the molecule. In this work it is shown that no polymer is formed when the acetone solutions 4,4' diamino diphenyl sulphone (DDS) and hexamethylene diisocyanate (HDI) merge. After standing for 24 hours and diluting with benzene, a low-molecular substance is precipitated which, in elementary composition and molecular weight, :is the product of the reaction of two diamine molecules and two diisocyanate molecules. A second substance was separated from the benzene-acetone solution, which is a primary product of the polymerization of one diamine molecule with * Vysokomol. soey4. 5: No. 6, 822-825, 1963. 1540
Reaction of diamines with diisocyanates
1541
one diisocyanate molecule, the ratio o f the first to the second b y weight being 1 : 1.4. I t is interesting to n o t e t h a t the reaction showed no p r o d u c t s containing diamine a n d diisocyanate in o t h e r ratios. I t can, for instance, he assumed t h a t as a result of the i n t e r a c t i o n of D D S with H D I a p r i m a r y p r o d u c t will be f o r m e d w i t h the structure:
0CN(CH,).NHCONH~----~S0,~--__~ NH2, which will be p a r t i a l l y dimerized with f o r m a t i o n of:
0CN [(CH,).NHCONH~S0,~/~NH
CONH] H.
I f the first reaction is c o m p l e t e d t h e n the second will only be 580/o completed. W h e n the reaction occurs u n d e r these conditions no more high-molecular p r o d u c t is formed. I t is k n o w n t h a t the r e a c t i o n of amines with isocyanates m a y accelerate the effect of a c a t a l y s t o f the t e r t i a r y amine t y p e [3]. W e h a v e shown t h a t , even when a small a m o u n t o f t e r t i a r y amines are a d d e d to an acetone solution o f D D S a n d H D I , a p o l y m e r is formed. The r a t e o f p o l y m e r f o r m a t i o n depends b o t h on the n a t u r e of the c a t a l y s t a n d on its c o n c e n t r a t i o n in the reaction m e d i u m (Table 1). TABLE 1. R E A C T I O N
OF
4,4'
DIAMINO D I P t I E N Y L SULPHONE W I T H
H E X A M E T H Y L E N E DIISOCYANATE IN T H E PRESENCE OF CATALYSTS
Catalyst
Triethyl amine
Piridin
Dimethyl aniline
Catalyst I Time required for polycontent, ~o of I mer to separate to the total starting amount of 58% of the materials theoretical, hr 1 2.5 5 7"5 10 12 1 2.5 5 7-5 I0 12 1 2.5 5 7.5 l0 12
8 3 1.5 0.3 0.35 0.25 24 7 3-5 3 2.5 2.25 48 16 5.5 5 5 4.5
1542
O. Y),. FEDOTOV),and A. G. GROZDOV
I t follows from these results t h a t the best o f the c a t a l y s t s which we tested is t r i e t h y l amine. F o r instance, the efficiency o f the c a t a l y s t falls with the dissociation c o n s t a n t o f the t e r t i a r y a m i n e K(c,H~i,~ = 5 . 6 5 × 10 -4, K c ~ , ~ = 2 . 3 × 10-9; K(CH,),~HC,H = 1" 10 -9. A t the same time the reaction rate rises with the c o n c e n t r a t i o n o f the catalyst. F o r t r i e t h y l a m i n e with a c o n c e n t r a t i o n o f 7-8 % the reaction rate o f D D S polymerization with H D I becomes a p p r o x i m a t e l y the same as t h a t o f an ionic reaction. I f the reaction is carried o u t in acetone in the presence o f t r i e t h y l a m i n e for 15 minutes, 5 8 % o f p o l y m e r is separated from the solution. The p a r t o f the p r o d u c t s of the reaction which were soluble in acetone, was divided into three fractions which were t h e n investigated. The results o f these studies are s h o w n in Table 2. I t follows from the analysis of the fractions t h a t the m o s t high molecular p a r t is t h a t p a r t o f the material which was precipitated from the acetone solution. The v e r y low molecular part, which is soluble in water, is the original diamine. The i n t e r m e d i a t e fractions are oligomers with molecular weights 780-1950. A t t e n t i o n is d r a w n to the fact t h a t the sulphur a n d nitrogen c o n t e n t corresponds to an oligomer structure, h a v i n g isocygnate groups at b o t h ends o f the molecule. Besides this diamine which h a d n o t entered into the reaction was also f o u n d in the products, b u t no free diisocyanate. This is indirect p r o o f o f the influence o f the catalysts on the reaction a c t i v i t y of diisoeyanate.
EXPERIMENTAL The polymerization of 4,4" diamino diphenyl sulphone with hexamethyl methylene diiso cyanate To3 g DDS dissolved in 30 ml acetone, was added a solution of 2 g HDI in 20 ml acetone. The mixture was held for 24 hours at room temperature and then benzene was added until the reaction products insoluble in benzene was fully separated, and it was then dried in a vacuum exsiccator and analysed. The soluble part of the substance was separated from the solution by distilling off the solvent and then it also was analysed. The results of the analysis are shown in Table 3. Polymerization of 4,4' diamino diphenyl sulphone with hexamethylene diisocyanate in the presence of a catalyst. To 3 g DDS dissolved in 30 ml acetone was added a solution of 2 g HDI in 20 ml acetone. To this was added a calculated amount of the catalyst dissolved in acetone. The solution was held at room temperature until a jelly-like substance was separated. The yield of polymer under these conditions was found to be ~ 80% independent of the catalyst used and of its quantity, the only change being in the time required for formation of the polymer. For the fractionation a polymer was used under the conditions outlined above in the presence of 10% triethyl amine. The resulting jelly-like deposit was filtered off through a Biiehner funnel and washed in acetone and dried in a vacuum. The following were determined: molecular weight of the polymer from its end groups, amine and isoeyanate number and elementary composition. Benzene was added to the mother solution obtained after removing the polymer, until the insoluble products of the reaction had fully precipitated. After removing the solvent mixture the residue was treated in hot water. The part of the substance which was soluble
7-5 7-2
14.1 13.45 13.4 13.9
5.78 6.00 6.1 5.55
58.30 58.00
57.8 57.1
Fraction insoluble in water and benzene
Polymer fraction
Fraction soluble i n benzene F r a c t i o n insoluble i n benzene
Fraction
1950
6.9 7.1
14.5 14.27
6.11 5.78
57 "4 57"4
F r a c t i o n soluble i n m i x t u r e o f acetone-benzene
58.1 57.5
58.2 57-5
420
850
Molecular weight
780
5.5 6.2
11.6 11.2
4.96 4.71
58 57"6
F r a c t i o n soluble i n w a t e r
4300
1830
850
260
End group
3"4
5
264
S
7.7 7.65
7.8 7.6
H
6.00 5.75
5.78 5.80
Elementary composition, %
13.27
13.4
N
~
--
i co
Suggested formula of product
/cI ,)01, co
20
S 7"65
7"7
5"8
5.75
57"8
57.5
416
832
Elementary composition, %
--
5
H
13.6
39
8O
100
13.4
13'5
N
80
100
95
end isocyanate groups
C
Mole -
TABLE 3. COMPOSITION OF FRACTIONS OF COPOLYMER D D S AND H D I
240
12.95 12.9
N
H
Cryoseopic
Content, % of theoretical
IsocyAmine anat~ No. end No. amino groups
D D S AND H D I
Molecular weight
C
Fraction
Elementary composition, %
T A B L E 2. P R O P E R T I E S OF FRACTIONS OF T H E COPOLYMERS
O
~r
o
o
1544
S. S. ~IKOLAYEVAet al.
sn hot water was removed from it on cooling. The products of the reaction, both the waterioluble and insoluble ones, were analysed. The part of the substance soluble in the benzeneacetone mixture was separated and studied as described above. The analytical data is shown in Table 2. The molecular weight was determined in all cases by the Rast eryoscopie method, and in some cases also by the end group method. The isocyanate and amine numbers were determined by the usual method [4]. CONCLUSIONS
(1) P o l y u r e a s h a v e b e e n synthesized for the first t i m e on t h e basis o f h e x a m e t h y l d i i s o c y a n a t e a n d 4,4' d i a m i n o d i p h e n y l sulphone. (2) I t h a s been f o u n d t h a t t e r t i a r y a m i n e s h a v e a n accelerating effect on the reaction. I t has been shown t h a t t h e a c t i v i t y o f t h e c a t a l y s t falls w i t h reduction in its dissociation constant. (3) I n t e r m e d i a t e p r o d u c t s o f the r e a c t i o n o f 4,4' d i a m i n o d i p h e n y l sulphone w i t h h e x a m e t h y l e n e d i i s o c y a n a t e h a v e been s e p a r a t e d , which show s o m e reg u l a r i t y in the p o l y m e r i z a t i o n o f these substances. Translated by V. ALFORD
REFERENCES
1. A. A. STREPIKHEYEV, A. A. ARTEM'EV and A. Ira. SHaMIDT, Issled. v oblasti vysokomol. soyed. (Investigations in the Sphere of Polymers.) Izd. Akad. l~auk. SSSR, 1949 2. O. Ya. FEDOTOVA, I. P. LOSEV and N. M. SKRIPCHENK0 et al., Vysokomol. soyed. 5 : 168, 1963 3. L W. BAKER and D. N. BAILEY, J. Chem. Soc. 4646, 1927 4. I. P. LOSEV and O. Ya. FEDOTOVA, Praktikum po khimii vysokomol, soyed. (Practical Chemistry of Polymers.) Goskhimizdat, Moscow, 1959
STRUCTURAL CHARACTERISTICS OF POLYAMIDES PREPARED BY THE INTERFACIAL POLYCONDENSATION METHOD* S. S. NIKOLAYEVA, E. Z. F A I N B E R G a n d N. V. M I K H A I L O V All-Union Research Institute of Synthetic Fibres (Received 14 November 1961)
2~_ PROMISING m e t h o d of p r o d u c i n g p o l y m e r s is t h a t o f p o l y c o n d e n s a t i o n on a n interface. Two t y p i c a l features o f this m e t h o d h a v e b e e n noted: t h e r a p i d course o f the r e a c t i o n a n d certain difficulties c o n n e c t e d w i t h r e g u l a t i n g t h e * Vysokomol. soyed. 5: No. 6, 826-830, 1963.
POLYURETHANES are known to be produced b y the interaction of diamines with diisocyanates. In this process the solutions of the initial materials merge t o form a common solvent, and the reaction occurs at a rate which in some cases is very close to that of ionic reactions [1]. The rate of this reaction depends o n the reactive capacity of the diamines and diisocyanates and, consequently, ~)n their chemical structure. The reactive capacity of the diamines is determined b y the extent of their basicity, which falls as one passes from the aliphatic to ~he aromatic series. In its turn, the reactive capacity of aromatic diamines depends on the nature o f the amino groups, the presence of substitutes in the nucleus and on their influence. Thus Fedotova and Skripchenko et al. [2], have shown that the primary 4iamines of the series 4,4' diamino diphenyl methane have greater reactive capacity than the diamines of the series 4,4' diamino ditolyl methane substituted in the series, the first being more active than the second. The reactive capacity ~)f the secondary diamines of these series falls as the number of carbon atoms :in the substituent rises in the presence of nitrogen [2]. In its turn the reactive capacity of the diisocyanates falls as one passes from aromatic to aliphatic series [2]. The existence and structure of the bridge between t h e nuclei also affects the reactive capacity of the binuclear aromatic diamines. F o r instance, benzidiene has a greater reactive capacity than diamino diphenyl methane, while diamino diphenyl sulphone has very low activity in the reaction with diisocyanates. It has very weak basic properties due to the presence of the ~lectrophile group --S02--, which repulses the electron cloud of the molecule. In this work it is shown that no polymer is formed when the acetone solutions 4,4' diamino diphenyl sulphone (DDS) and hexamethylene diisocyanate (HDI) merge. After standing for 24 hours and diluting with benzene, a low-molecular substance is precipitated which, in elementary composition and molecular weight, :is the product of the reaction of two diamine molecules and two diisocyanate molecules. A second substance was separated from the benzene-acetone solution, which is a primary product of the polymerization of one diamine molecule with * Vysokomol. soey4. 5: No. 6, 822-825, 1963. 1540
Reaction of diamines with diisocyanates
1541
one diisocyanate molecule, the ratio o f the first to the second b y weight being 1 : 1.4. I t is interesting to n o t e t h a t the reaction showed no p r o d u c t s containing diamine a n d diisocyanate in o t h e r ratios. I t can, for instance, he assumed t h a t as a result of the i n t e r a c t i o n of D D S with H D I a p r i m a r y p r o d u c t will be f o r m e d w i t h the structure:
0CN(CH,).NHCONH~----~S0,~--__~ NH2, which will be p a r t i a l l y dimerized with f o r m a t i o n of:
0CN [(CH,).NHCONH~S0,~/~NH
CONH] H.
I f the first reaction is c o m p l e t e d t h e n the second will only be 580/o completed. W h e n the reaction occurs u n d e r these conditions no more high-molecular p r o d u c t is formed. I t is k n o w n t h a t the r e a c t i o n of amines with isocyanates m a y accelerate the effect of a c a t a l y s t o f the t e r t i a r y amine t y p e [3]. W e h a v e shown t h a t , even when a small a m o u n t o f t e r t i a r y amines are a d d e d to an acetone solution o f D D S a n d H D I , a p o l y m e r is formed. The r a t e o f p o l y m e r f o r m a t i o n depends b o t h on the n a t u r e of the c a t a l y s t a n d on its c o n c e n t r a t i o n in the reaction m e d i u m (Table 1). TABLE 1. R E A C T I O N
OF
4,4'
DIAMINO D I P t I E N Y L SULPHONE W I T H
H E X A M E T H Y L E N E DIISOCYANATE IN T H E PRESENCE OF CATALYSTS
Catalyst
Triethyl amine
Piridin
Dimethyl aniline
Catalyst I Time required for polycontent, ~o of I mer to separate to the total starting amount of 58% of the materials theoretical, hr 1 2.5 5 7"5 10 12 1 2.5 5 7-5 I0 12 1 2.5 5 7.5 l0 12
8 3 1.5 0.3 0.35 0.25 24 7 3-5 3 2.5 2.25 48 16 5.5 5 5 4.5
1542
O. Y),. FEDOTOV),and A. G. GROZDOV
I t follows from these results t h a t the best o f the c a t a l y s t s which we tested is t r i e t h y l amine. F o r instance, the efficiency o f the c a t a l y s t falls with the dissociation c o n s t a n t o f the t e r t i a r y a m i n e K(c,H~i,~ = 5 . 6 5 × 10 -4, K c ~ , ~ = 2 . 3 × 10-9; K(CH,),~HC,H = 1" 10 -9. A t the same time the reaction rate rises with the c o n c e n t r a t i o n o f the catalyst. F o r t r i e t h y l a m i n e with a c o n c e n t r a t i o n o f 7-8 % the reaction rate o f D D S polymerization with H D I becomes a p p r o x i m a t e l y the same as t h a t o f an ionic reaction. I f the reaction is carried o u t in acetone in the presence o f t r i e t h y l a m i n e for 15 minutes, 5 8 % o f p o l y m e r is separated from the solution. The p a r t o f the p r o d u c t s of the reaction which were soluble in acetone, was divided into three fractions which were t h e n investigated. The results o f these studies are s h o w n in Table 2. I t follows from the analysis of the fractions t h a t the m o s t high molecular p a r t is t h a t p a r t o f the material which was precipitated from the acetone solution. The v e r y low molecular part, which is soluble in water, is the original diamine. The i n t e r m e d i a t e fractions are oligomers with molecular weights 780-1950. A t t e n t i o n is d r a w n to the fact t h a t the sulphur a n d nitrogen c o n t e n t corresponds to an oligomer structure, h a v i n g isocygnate groups at b o t h ends o f the molecule. Besides this diamine which h a d n o t entered into the reaction was also f o u n d in the products, b u t no free diisocyanate. This is indirect p r o o f o f the influence o f the catalysts on the reaction a c t i v i t y of diisoeyanate.
EXPERIMENTAL The polymerization of 4,4" diamino diphenyl sulphone with hexamethyl methylene diiso cyanate To3 g DDS dissolved in 30 ml acetone, was added a solution of 2 g HDI in 20 ml acetone. The mixture was held for 24 hours at room temperature and then benzene was added until the reaction products insoluble in benzene was fully separated, and it was then dried in a vacuum exsiccator and analysed. The soluble part of the substance was separated from the solution by distilling off the solvent and then it also was analysed. The results of the analysis are shown in Table 3. Polymerization of 4,4' diamino diphenyl sulphone with hexamethylene diisocyanate in the presence of a catalyst. To 3 g DDS dissolved in 30 ml acetone was added a solution of 2 g HDI in 20 ml acetone. To this was added a calculated amount of the catalyst dissolved in acetone. The solution was held at room temperature until a jelly-like substance was separated. The yield of polymer under these conditions was found to be ~ 80% independent of the catalyst used and of its quantity, the only change being in the time required for formation of the polymer. For the fractionation a polymer was used under the conditions outlined above in the presence of 10% triethyl amine. The resulting jelly-like deposit was filtered off through a Biiehner funnel and washed in acetone and dried in a vacuum. The following were determined: molecular weight of the polymer from its end groups, amine and isoeyanate number and elementary composition. Benzene was added to the mother solution obtained after removing the polymer, until the insoluble products of the reaction had fully precipitated. After removing the solvent mixture the residue was treated in hot water. The part of the substance which was soluble
7-5 7-2
14.1 13.45 13.4 13.9
5.78 6.00 6.1 5.55
58.30 58.00
57.8 57.1
Fraction insoluble in water and benzene
Polymer fraction
Fraction soluble i n benzene F r a c t i o n insoluble i n benzene
Fraction
1950
6.9 7.1
14.5 14.27
6.11 5.78
57 "4 57"4
F r a c t i o n soluble i n m i x t u r e o f acetone-benzene
58.1 57.5
58.2 57-5
420
850
Molecular weight
780
5.5 6.2
11.6 11.2
4.96 4.71
58 57"6
F r a c t i o n soluble i n w a t e r
4300
1830
850
260
End group
3"4
5
264
S
7.7 7.65
7.8 7.6
H
6.00 5.75
5.78 5.80
Elementary composition, %
13.27
13.4
N
~
--
i co
Suggested formula of product
/cI ,)01, co
20
S 7"65
7"7
5"8
5.75
57"8
57.5
416
832
Elementary composition, %
--
5
H
13.6
39
8O
100
13.4
13'5
N
80
100
95
end isocyanate groups
C
Mole -
TABLE 3. COMPOSITION OF FRACTIONS OF COPOLYMER D D S AND H D I
240
12.95 12.9
N
H
Cryoseopic
Content, % of theoretical
IsocyAmine anat~ No. end No. amino groups
D D S AND H D I
Molecular weight
C
Fraction
Elementary composition, %
T A B L E 2. P R O P E R T I E S OF FRACTIONS OF T H E COPOLYMERS
O
~r
o
o
1544
S. S. ~IKOLAYEVAet al.
sn hot water was removed from it on cooling. The products of the reaction, both the waterioluble and insoluble ones, were analysed. The part of the substance soluble in the benzeneacetone mixture was separated and studied as described above. The analytical data is shown in Table 2. The molecular weight was determined in all cases by the Rast eryoscopie method, and in some cases also by the end group method. The isocyanate and amine numbers were determined by the usual method [4]. CONCLUSIONS
(1) P o l y u r e a s h a v e b e e n synthesized for the first t i m e on t h e basis o f h e x a m e t h y l d i i s o c y a n a t e a n d 4,4' d i a m i n o d i p h e n y l sulphone. (2) I t h a s been f o u n d t h a t t e r t i a r y a m i n e s h a v e a n accelerating effect on the reaction. I t has been shown t h a t t h e a c t i v i t y o f t h e c a t a l y s t falls w i t h reduction in its dissociation constant. (3) I n t e r m e d i a t e p r o d u c t s o f the r e a c t i o n o f 4,4' d i a m i n o d i p h e n y l sulphone w i t h h e x a m e t h y l e n e d i i s o c y a n a t e h a v e been s e p a r a t e d , which show s o m e reg u l a r i t y in the p o l y m e r i z a t i o n o f these substances. Translated by V. ALFORD
REFERENCES
1. A. A. STREPIKHEYEV, A. A. ARTEM'EV and A. Ira. SHaMIDT, Issled. v oblasti vysokomol. soyed. (Investigations in the Sphere of Polymers.) Izd. Akad. l~auk. SSSR, 1949 2. O. Ya. FEDOTOVA, I. P. LOSEV and N. M. SKRIPCHENK0 et al., Vysokomol. soyed. 5 : 168, 1963 3. L W. BAKER and D. N. BAILEY, J. Chem. Soc. 4646, 1927 4. I. P. LOSEV and O. Ya. FEDOTOVA, Praktikum po khimii vysokomol, soyed. (Practical Chemistry of Polymers.) Goskhimizdat, Moscow, 1959
STRUCTURAL CHARACTERISTICS OF POLYAMIDES PREPARED BY THE INTERFACIAL POLYCONDENSATION METHOD* S. S. NIKOLAYEVA, E. Z. F A I N B E R G a n d N. V. M I K H A I L O V All-Union Research Institute of Synthetic Fibres (Received 14 November 1961)
2~_ PROMISING m e t h o d of p r o d u c i n g p o l y m e r s is t h a t o f p o l y c o n d e n s a t i o n on a n interface. Two t y p i c a l features o f this m e t h o d h a v e b e e n noted: t h e r a p i d course o f the r e a c t i o n a n d certain difficulties c o n n e c t e d w i t h r e g u l a t i n g t h e * Vysokomol. soyed. 5: No. 6, 826-830, 1963.