# US 5,705,571 A · Process for selective hydrogenation of conjugated diene polymer

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- Number: US 5,705,571 A
- Document ID: US5705571A
- Status: Granted
- Kind: A
- Application number: 08/670,126
- Filed: 1996-06-25
- Granted: 1998-01-06
- Earliest claimed: 1996-05-17
- Assignees: Taiwan Synthetic Rubber Corporation
- Inventors: Raymond Chien-Chao Tsiang; Henry Chi-Chen Hsieh; Wen-Shien Yang
- Web page: https://patentgrep.com/patent/US5705571A

## CPC

- C08F 8/04: Reduction, e.g. hydrogenation
- C08C 19/02: Hydrogenation
- C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08C: TREATMENT OR CHEMICAL MODIFICATION OF RUBBERS

## Abstract

The present invention provides a process for selective hydrogenation of a conjugated diene polymer. The process includes bringing the conjugated diene polymer in an inert organic solvent into contact with hydrogen in the presence of a specific hydrogenation catalyst combination including (A) a substituted or unsubstituted bis(cyclopentadienyl) Group VIII transition metal compound and (B) an organic lithium compound. The hydrogenation can be carried out in the presence of a small amount of the hydrogenation catalyst combination under mild conditions, and both the hydrogenation conversion and selectivity to conjugated diene units are high.

## Claims

### Claim 1

A process for selective hydrogenation of a conjugated diene polymer, the conjugated diene polymer being a homopolymer of a conjugated diene, a copolymer of two or more conjugated dienes or a copolymer of at least one conjugated diene and at least one vinyl aromatic hydrocarbon, said process comprising bringing the conjugated diene polymer in an inert organic solvent into contact with hydrogen in the presence of a hydrogenation catalyst combination to selectively hydrogenate the unsaturated double bonds in the conjugated diene units of the conjugated diene polymer,
wherein the hydrogenation catalyst combination includes at least one catalyst (A) and at least one catalyst (B),
wherein the catalyst (A) is an unsubstituted or substituted bis(cyclopentadienyl) Group VIII transition metal compound, which is represented by the following formula:
(C.sub.5 R.sub.n R'.sub.5-n)(C.sub.5 R.sub.m R".sub.5-m)M
wherein
R, R' and R" are the same or different and are selected from the group consisting of hydrogen, C.sub.1 -C.sub.8 alkyl and alkoxy groups, C.sub.6 -C.sub.8 aryl and aryloxy groups, C.sub.6 -C.sub.8 cycloalkyl and cycloalkoxy groups, C.sub.1 -C.sub.5 hydroxyalkyl groups, aldehyde groups, carboxyl groups, silyl groups,
m and n are integers independently from 0 to 5,
C.sub.5 R.sub.n R'.sub.5-n and C.sub.5 R.sub.m R".sub.5-m are the same or different unsubstituted or substituted cyclopentadienyl groups,
M is a Group VIII transition metal selected from the group consisting of cobalt, nickel, rhodium, palladium, platinum and iridium,
wherein the catalyst (B) is an organic lithium compound having at least one lithium atom or is lithium hydride,
wherein the organic lithium compound is selected from the group consisting of R"'Li and R"'Li.sub.2,
wherein R"' is a C.sub.1 -C.sub.30 hydrocarbon moiety or a polymeric moiety,
wherein the molar ratio of lithium atom to M atom is from 0.1 to 100.

### Claim 2 (depends on 1)

The process as claimed in claim 1, wherein the conjugated diene is selected from the group consisting of 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 4,5-diethyl-1,3-octadiene and 3-butyl-1,3-octadiene.

### Claim 3 (depends on 1)

The process as claimed in claim 1, wherein the vinyl aromatic hydrocarbon is selected from the group consisting of styrene, t-butyl styrene, .alpha.-methyl styrene, o-methyl styrene, p-methyl styrene, divinyl benzene, 1,1-diphenyl ethylene, vinyl naphthalene, N,N-dimethyl-p-ethyl styrene and N,N-diethyl-p-aminoethylstyrene.

### Claim 4 (depends on 1)

The process as claimed in claim 1, wherein the conjugated diene polymer is a homopolymer of a conjugated diene or a copolymer of two or more conjugated dienes.

### Claim 5 (depends on 4)

The process as claimed in claim 4, wherein the conjugated diene polymer is a polymer of 1,3-butadiene and/or isoprene.

### Claim 6 (depends on 5)

The process as claimed in claim 5, wherein the 1,2-vinyl bond content of conjugated diene units in the conjugated diene polymer is 5% to 70%.

### Claim 7 (depends on 1)

The process as claimed in claim 1, wherein the conjugated diene polymer is a copolymer of at least one conjugated diene and at least one vinyl aromatic hydrocarbon.

### Claim 8 (depends on 7)

The process as claimed in claim 7, wherein the conjugated diene polymer is a copolymer of 1,3-butadiene and/or isoprene and styrene.

### Claim 9 (depends on 7)

The process as claimed in claim 7, wherein the conjugated diene polymer is a copolymer of 1,3-butadiene and styrene.

### Claim 10 (depends on 7)

The process as claimed in claim 7, wherein the conjugated diene polymer is a block copolymer having at least one conjugated diene polymer block and at least one vinyl aromatic hydrocarbon polymer block.

### Claim 11 (depends on 10)

The process as claimed in claim 10, wherein the vinyl aromatic hydrocarbon polymer block content in the block copolymer is 10 to 90% by weight based on the total weight of polymers.

### Claim 12 (depends on 10)

The process as claimed in claim 10, wherein the 1,2-vinyl bond content of conjugated diene units in the block copolymer is 20 to 70% by weight based on the total weight of the conjugated diene units.

### Claim 13 (depends on 1)

The process as claimed in claim 1, wherein the number-average molecular weight of the conjugated diene polymer is about 1,000 to about 1,000,000.

### Claim 14 (depends on 1)

The process as claimed in claim 1, wherein the hydrogenation catalyst (A) is selected from the group consisting of bis(cyclopentadienyl)cobalt(II), bis(cyclopentadienyl)nickel(II), bis(cyclopentadienyl)palladium, bis(cyclopentadienyl)platinum, bis(pentamethylcyclopentadienyl)cobalt(II), bis(pentamethylcyclopentadienyl)nickel(II), (methylcyclopentadienyl)(cyclopentadienyl)cobalt(II), (methylcyclopentadienyl)(cyclopentadienyl)nickel(II), (carboxycyclopentadienyl)(cyclopentadienyl)cobalt(II) and (carboxycyclopentadienyl)(cyclopentadienyl)nickel(II).

### Claim 15 (depends on 14)

The process as claimed in claim 14, wherein the hydrogenation catalyst (A) is selected from the group consisting of bis(cyclopentadienyl)cobalt(II) and bis(cyclopentadienyl)nickel(II).

### Claim 16 (depends on 1)

The process as claimed in claim 1, wherein the hydrogenation catalyst (B) is R"'Li, wherein R"' is a C.sub.1 -C.sub.20 hydrocarbon moiety.

### Claim 17 (depends on 16)

The process as claimed in claim 16, wherein the hydrogenation catalyst (B) is selected from the group consisting of methyl lithium, ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, tert-butyl lithium, n-pentyl lithium, n-hexyl lithium, phenyl lithium, benzyl lithium and styryl lithium.

### Claim 18 (depends on 16)

The process as claimed in claim 16, wherein R"' is a C.sub.1 -C.sub.20 alkyl group.

### Claim 19 (depends on 18)

The process as claimed in claim 18, wherein the hydrogenation catalyst (B) is selected from the group consisting of n-butyl lithium and sec-butyl lithium.

### Claim 20 (depends on 1)

The process as claimed in claim 1, wherein the hydrogenation catalyst (A) is present in an amount of 0.05 to 10 millimoles per 100 g of the conjugated diene polymer.

### Claim 21 (depends on 1)

The process as claimed in claim 1, wherein in the hydrogenation catalyst combination, the molar ratio of the catalyst (A) to the catalyst (B) is 0.5 to 10.

### Claim 22 (depends on 1)

The process as claimed in claim 1, wherein the hydrogenation is carried out at 20.degree. to 100.degree. C., under a hydrogen pressure of 2 to 50 kg/cm.sup.2.

### Claim 23 (depends on 1)

The process as claimed in claim 1, wherein at least 50% of the unsaturated double bonds in the conjugated diene units are hydrogenated.

### Claim 24 (depends on 23)

The process as claimed in claim 23, wherein at least 90% of the unsaturated double bonds in the conjugated diene units are hydrogenated.

### Claim 25 (depends on 7)

The process as claimed in claim 7, wherein at least 50% of the unsaturated double bonds in the conjugated diene units are selectively hydrogenated, and not more than 10% of the unsaturated double bonds in the vinyl aromatic hydrocarbon units are hydrogenated.

### Claim 26 (depends on 25)

The process as claimed in claim 25, wherein at least 90% of the unsaturated double bonds in the conjugated diene units are selectively hydrogenated, and not more than 5% of the unsaturated double bonds in the vinyl aromatic hydrocarbon units are hydrogenated.

### Claim 27 (depends on 11)

The process as claimed in claim 11, wherein in the block copolymer, the 1,2-vinyl bonds content is 30 to 70% by weight of the total conjugated diene units.

### Claim 28 (depends on 10)

The process as claimed in claim 10, wherein at least 50% of the unsaturated double bonds in the conjugated diene units are selectively hydrogenated, and not more than 10% of the unsaturated double bonds in the vinyl aromatic hydrocarbon units are hydrogenated.

### Claim 29 (depends on 11)

The process as claimed in claim 11, wherein at least 50% of the unsaturated double bonds in the conjugated diene units are selectively hydrogenated, and not more than 10% of the unsaturated double bonds in the vinyl aromatic hydrocarbon units are hydrogenated.

### Claim 30 (depends on 12)

The process as claimed in claim 12, wherein at least 50% of the unsaturated double bonds in the conjugated diene units are selectively hydrogenated, and not more than 10% of the unsaturated double bonds in the vinyl aromatic hydrocarbon units are hydrogenated.

### Claim 31 (depends on 13)

The process as claimed in claim 13, wherein at least 50% of the unsaturated double bonds in the conjugated diene units are selectively hydrogenated, and not more than 10% of the unsaturated double bonds in the vinyl aromatic hydrocarbon units are hydrogenated.

### Claim 32 (depends on 1)

The process as claimed in claim 1, wherein the hydrogenation catalyst (B) is represented by the formula R"'Li, wherein R"' is a polymeric moiety.

### Claim 33 (depends on 32)

The process as claimed in claim 32, wherein the hydrogenation catalyst (B) is a conjugated diene living polymer containing a lithium atom in the polymer chain thereof and having a number-average molecular weight in the range of from 1,000 to 1,000,000, the conjugated diene living polymer being a living homopolymer of a conjugated diene, a living copolymer of two or more conjugated dienes or a living copolymer of at least one conjugated diene and at least one vinyl aromatic hydrocarbon obtained by using an organic lithium compound as a polymerization catalyst.

### Claim 34 (depends on 33)

The process as claimed in claim 33, wherein the hydrogenation catalyst (A) is bis(cyclopentadienyl)cobalt(II) or bis(cyclopentadienyl)nickel(II).

### Claim 35 (depends on 34)

The process as claimed in claim 34, wherein the hydrogenation catalyst (A) is present in a amount of 0.005 to 10 millimoles per 100 g of the conjugated diene polymer.

### Claim 36 (depends on 33)

The process as claimed in claim 33, wherein the conjugated diene living polymer is a living polymer of 1,3-butadiene and/or isoprene.

### Claim 37 (depends on 33)

The process as claimed in claim 33, wherein the conjugated diene living polymer is a living copolymer of 1,3-butadiene and/or isoprene and styrene.

### Claim 38 (depends on 33)

The process as claimed in claim 33, wherein the conjugated diene living polymer is a living copolymer of 1,3-butadiene and styrene.

### Claim 39 (depends on 37)

The process as claimed in claim 37, wherein the conjugated diene living copolymer has at least one 1,3-butadiene and/or isoprene block and at least one styrene block in which the styrene block content is in the range of 10 to 90% by weight of the total weight of the polymer, and the 1,2-vinyl bond content is in the range of 30 to 70% by weight in the 1,3-butadiene and/or isoprene units.

### Claim 40 (depends on 39)

The process as claimed in claim 39, wherein at least 90% of the unsaturated double bonds in the 1,3-butadiene and/or isoprene units are selectively hydrogenated, and not more than 5% of the unsaturated double bonds in the styrene units are hydrogenated.

### Claim 41

A process for selective hydrogenation of a conjugated diene polymer, the conjugated diene polymer being a homopolymer of a conjugated diene, a copolymer of two or more conjugated dienes or a copolymer of at least one conjugated diene and at least one vinyl aromatic hydrocarbon, said process comprising bringing the conjugated diene polymer in an inert organic solvent into contact with hydrogen in the presence of a hydrogenation catalyst combination to selectively hydrogenate the unsaturated double bonds in the conjugated diene units of the conjugated diene polymer,
wherein the hydrogenation catalyst combination includes at least one catalyst (A) and at least one catalyst (B),
wherein the catalyst (A) is an unsubstituted or substituted bis(cyclopentadienyl) Group VIII transition metal compound, which is represented by the following formula:
(C.sub.5 R.sub.n R'.sub.5-n)(C.sub.5 R.sub.m R".sub.5-m)M
wherein
R, R' and R" are the same or different, and are selected from the group consisting of hydrogen, C.sub.1 -C.sub.8 alkyl and alkoxy groups, C.sub.6 -C.sub.8 aryl and aryloxy groups, C.sub.6 -C.sub.8 cycloalkyl and cycloalkoxy groups, C.sub.1 -C.sub.5 hydroxyalkyl groups, aldehyde groups, carboxyl groups, silyl groups.
m and n are integers independently from 0 to 5,
C.sub.5 R.sub.n R'.sub.5-n and C.sub.5 R.sub.m R".sub.5-m are the same or different unsubstituted or substituted cyclopentadienyl groups,
M is a Group VIII transition metal selected from the group consisting of cobalt and nickel,
wherein the catalyst (B) is an organic lithium compound having at least one lithium atom or is lithium hydride,
wherein the organic lithium compound is selected from the group consisting of R"'Li and R"'Li.sub.2,
wherein R"' is a C.sub.1 -C.sub.30 hydrocarbon moiety or a polymeric moiety,
wherein the molar ratio of lithium atom to M atom is from 0.1 to 100.

### Claim 42

A process for selective hydrogenation of a conjugated diene polymer, the conjugated diene polymer being a homopolymer of a conjugated diene, a copolymer of two or more conjugated dienes or a copolymer of at least one conjugated diene and at least one vinyl aromatic hydrocarbon, said process comprising bringing the conjugated diene polymer in an inert organic solvent into contact with hydrogen in the presence of a hydrogenation catalyst combination to selectively hydrogenate the unsaturated double bonds in the conjugated diene units of the conjugated diene polymer,
wherein the hydrogenation catalyst combination includes at least one catalyst (A) and at least one catalyst (B),
wherein the catalyst (A) is selected from the group consisting of bis(cyclopentadienyl)cobalt(II) and bis(cyclopentadienyl)nickel(II),
wherein the catalyst (B) is an organic lithium compound R"' Li, wherein R"' is a C.sub.1 -C.sub.20 hydrocarbon moiety, wherein the molar ratio of lithium atom to M atom is from 0.1 to 100.