JP2836155B2 - Catalyst for producing trans 1,4 polybutadiene and method for producing selective trans 1,4 polybutadiene - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a polymerization catalyst for selectively providing trans 1,4 polybutadiene and a method for selectively producing trans 1,4 polybutadiene using the same.

More specifically, a catalyst composed of a transition metal compound and an organoaluminum compound and at least 50%, usually 60 to 90%, of the butadiene unit containing the same, and under appropriate polymerization conditions, at least 90% of the butadiene units have a trans-1,4-type arrangement. The present invention relates to a method for producing a bonded butadiene compound polymer.

<Prior Art> Conventionally, as a method for producing a diene compound polymer, various methods such as radical polymerization, cationic polymerization, anionic polymerization, and coordination anionic polymerization using a Ziegler-Natta catalyst are known. Further, examples of providing trans 1,4 polybutadiene include the solid catalyst TiCl ₃ by Natta et al.
And Triethylaluminum (Gazzeta Chimica Italiana, 1959, Vol. 89, p. 761) and a system using soluble VCl ₄ and triethylaluminum [La Chimica e Industria] 1959, Vol. 41, 116]. However, these disclosed methods have a problem that they have low activity and cannot be used for industrial production.

<Problems to be Solved by the Invention> Under such circumstances, the problem to be solved by the present invention is to provide a novel catalyst for polymerizing a soluble butadiene compound instead of the above transition metal catalyst, and to use the catalyst for butadiene units contained therein. At least 50% or more, usually 60 to 90%, and under appropriate polymerization conditions, 90% or more is a production method that gives a high yield of a butadiene compound polymer bonded to a trans 1,4-type sequence.

<Means for Solving the Problems> The present invention provides a catalyst system comprising a transition metal compound having a specific structure and an organoaluminum, and a highly efficient catalyst system using the same.
The present invention relates to a method for obtaining high molecular weight trans 1,4 polybutadiene.

That is, the present invention provides a catalyst component (A) having the general formula: M (R) _l (OR ') mXn- (l +
m) (wherein, M represents a transition metal atom, R and R 'represent a hydrocarbon group having 1 to 20 carbon atoms, X represents a halogen atom, and l, m, and n represent l ≧ 0 and m ≧
0, n- (l + m) ≧ 0. n corresponds to the valence of the transition metal. ) And a catalyst component (B): General formula AlR ₁ aX ′ _3-a (R ¹ is _a compound having ¹ carbon atom
A hydrocarbon group, X 'is a halogen atom, a is a number of 1≤a≤3), and a catalyst component (C): general formulas I, II, III, IV, V Or an organic compound having at least two hydroxyl groups as shown in VI (Wherein R ″, R is a hydrocarbon group having 1 to 20 carbon atoms, Y is a hydrocarbon group having 1 to 20 carbon atoms, (R ⁶ represents hydrogen or a hydrocarbon group having 1 to 6 carbon atoms.)
Represents Here, R ² , R ³ , R ⁴ and R ⁵ represent a hydrocarbon group having 1 to 20 carbon atoms, a hydroxyl group, a nitro group, a nitrile group, a hydrocarboxy group or a halogen atom. In this case R ² ,
R ³ , R ⁴ and R ⁵ may be the same or different.
n ′ is 0 or an integer of 1 or more, and represents the number of repetitions of the unit Y. Y, y ', y ", y, z, z', z" and z represent the number of substituents bonded to the aromatic ring. y, y ′, z
And z 'is 0 or an integer from 1 to 4, y ", z" is 0 or an integer from 1 to 2, and y, z is 0 or an integer from 1 to 3. ), And a method for selectively producing trans 1,4 polybutadiene using the above catalyst system.

 Hereinafter, the contents of the present invention will be described in detail.

General formula M (R) used as catalyst component (A) in the present invention
_{In the} transition metal compound represented by _l (OR ') mXn- (l + m), specific examples of M include titanium, zirconium, hafnium, and vanadium, and titanium and zirconium give preferable results.

R or R 'is a hydrocarbon group having 1 to 20 carbon atoms, and among them, an alkyl group having 2 to 18 carbon atoms and an aryl group having 6 to 18 carbon atoms can be preferably used.

Specific examples of R or R 'include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, n-amyl, isoamyl, n-hexyl, n-heptyl, n
Alkyl groups such as -octyl, n-decyl and n-dodecyl; aryl groups such as phenyl and naphthyl; cycloalkyl groups such as cyclohexyl and cyclopentyl; allyl groups such as propenyl; and aralkyl groups such as benzyl.

Among them, R is preferably a methyl, ethyl, phenyl, benzyl group and the like, and R 'is preferably an alkyl group such as n-propyl, isopropyl, n-butyl and t-butyl and an aryl group such as phenyl. .

Examples of the halogen atom represented by X include chlorine, bromine and iodine. Particularly, chlorine is preferably used.

l, m, n are numbers satisfying l ≧ 0, m ≧ 0, n− (l + m) ≧ 0.

Specific examples of the catalyst component (A) include titanium tetrachloride, zirconium tetrachloride, tetraisopropoxy titanium, tetra-n-butoxy titanium, tetra-t-butoxy titanium, diphenoxy titanium dichloride, and dinaphthoxy titanium dichloride. , Tetraisopropoxyzirconium, tetra-n-butoxyzirconium or tetra-t
-Butoxyzirconium and the like.

General formula AlR ¹ aX ′ _3-a used as catalyst component (B)
(R ¹ is a hydrocarbon group having 1 to 20 carbon atoms, X ′ is a halogen atom, a
Specific examples of the organoaluminum compound represented by 1 ≦ a ≦ 3) include methylaluminum dichloride, ethylaluminum dichloride, n-propylaluminum dichloride, ethylaluminum sesquichloride, dimethylaluminum chloride, diethylaluminum chloride, Examples thereof include di-n-propylaluminum chloride, trimethylaluminum, triethylaluminum, triisobutylaluminum, ethyldicyclohexylaluminum, triphenylaluminum, diethylaluminum hydride, diisobutylaluminum hydride, diethylaluminum bromide, and diethylaluminum iodide.

Of these, diethylaluminum chloride, ethylaluminum sesquichloride and ethylaluminum dichloride give particularly favorable results.

General formula used as catalyst component (C) in the present invention In the compound represented by the formula, R ″, R is a hydrocarbon group having 1 to 20 carbon atoms, Y is a hydrocarbon group having 1 to 20 carbon atoms, —O
-, -S-, -SS-, (Where R ⁶ represents a hydrocarbon group having 1 to ⁶ carbon atoms). Examples of the hydrocarbon group having 1 to 20 carbon atoms represented by R ″, R and Y include methylene, ethylene, trimethylene, propylene, diphenylmethylene, isopropylidene, ethylidene, n-propylidene, isopropylidene, n
-Butylidene, isobutylidene and the like. Among them, methylene, ethylene, ethylidene, isopropylidene and isobutylidene groups are preferably used.

Here, n 'is an integer of 0 or 1 or more, and represents the number of repetitions of the unit Y. In particular, 0 or 1 gives a preferable result.

R ² , R ³ , R ⁴ and R ⁵ represent a hydrocarbon group having 1 to 20 carbon atoms, a hydroxyl group, a nitro group, a nitrile group, a hydrocarboxy group or a halogen atom. Examples of the hydrocarbon group having 1 to 20 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, n-amyl, isoamyl, n-hexyl, n-heptyl, n-octyl, Examples thereof include an alkyl group such as n-decyl and n-dodecyl, an aryl group such as phenyl and naphthyl, a cycloalkyl group such as cyclohexyl and cyclopentyl, an allyl group such as propenyl, and an aralkyl group such as benzyl. Among them, carbon number 1
Ten alkyl groups are preferably used.

y, y ', y ", y, z, z', z", z represents the number of substituents attached to the aromatic ring, and y, y ', z, z' represents 0 or 1 to 4
Integers up to y ″, z ″ are 0 or integers from 1 to 2, y, z
Represents 0 or an integer from 1 to 3.

Specific examples of the catalyst component (C) include, for example, 2,4-dihydroxypentane, 2- (2-hydroxypropyl) phenol, catechol, resorcinol, 4-isopropylcatechol, 3-methoxycatechol, 1,8-dihydroxynaphthalene. , 1,2-Dihydroxynaphthalene, 2,2'-biphenyldiol, 1,1'-bi-2-naphthol, 2,2'-dihydroxy-6,6'-dimethylbiphenyl, 4,4'6,6 ' −
Tetra-t-butyl-2,2'-methylenediphenol, 4,
4'-dimethyl-6,6'-di-tert-butyl-2,2'-methylenediphenol, 4,4 ', 6,6'-tetramethyl-2,2'
-Isobutylidene diphenol, 2,2'-dihydroxy-
3,3'-di-t-butyl-5,5'-dimethyldiphenyl sulfide and the like can be exemplified. Among them, 2,4'-dihydroxypentane, catechol, 2,2'-biphenyldiol, 1,1'-biphenyl-2-naphthol, 4,4 ', 6,6'-
Tetra-t-butyl-2,2'-methylenediphenol, 4,
4'-dimethyl-6,6'-di-tert-butyl-2,2'-methylenediphenol, 4,4 ', 6,6'-tetramethyl-2,2'
-Isobutylidene diphenol, 2,2'-dihydroxy-
3,3'-di-t-butyl-5,5'-dimethylphenylsulfide, 2,2'-dihydroxy-4,4 ', 6,6'-tetra-
t-Butyldiphenyl sulfide, 2,2'-dihydroxy-diphenyl sulfide gives favorable results.

When these catalyst systems are applied to the polymerization of a diene compound, the catalyst components (A), (B) and (C) are used.

The catalyst component (C) needs to be used after being reacted with the catalyst component (A) in advance before being subjected to polymerization.

The reaction can be carried out at a temperature of -20 ° C to 200 ° C in a hydrocarbon solvent or a polar solvent such as a halogenated hydrocarbon solvent or ether. Although the catalyst component (C) may be used directly in the reaction, when the catalyst component (A) is a halogen-containing transition metal compound, ammonia, ammonia, and the like are added to the reaction system in order to capture hydrogen halide generated during the reaction. It is also possible to add pyridine or alkylamine.

In this case, it is preferable to remove the hydrogen halide-containing compound and then subject it to polymerization.

The catalyst component (C) is previously reacted with an alkali metal such as sodium metal or a hydride of an alkali metal such as lithium hydride to synthesize a metal alcoholate, a metal phenolate, a metal naphtholate, etc. Is also good. In this case, it is preferable to remove the alkali metal salt and then conduct the polymerization. Further, when the catalyst component (A) contains a hydrocarboxy group,
It is also possible to react the catalyst component (C) with a carboxylic acid such as acetic acid in advance and to provide this reaction as an ester compound.

In the reaction between the transition metal compound and the organic compound having at least two hydroxyl groups, it is considered that a compound having a form in which at least two hydroxyl groups of the organic compound are bonded to the same transition metal is generated.

As the addition amount of each catalyst component, the catalyst component (A) is 10 ^-10 to 10 ³ mmol / l, preferably 10 ^-7 to 10 ² mm as a transition metal atom.
It can be used in the range of ol / l. Catalyst component (B) The catalyst component (A) can be used in an amount of 1 to 100,000, preferably 10 to 10,000 as an aluminum atom / transition metal atom. The catalyst component (C) is based on the transition metal atom of the catalyst component (A).
It can be used at 0.01 to 4 (mol ratio).

Specific examples of the butadiene compound applied in the present invention include 1,3-butadiene and isoprene.

The polymerization method is not particularly limited. For example, the solvent may be an aliphatic hydrocarbon solvent such as butane, pentane, hexane, heptane, or octane; an aromatic hydrocarbon solvent such as benzene or toluene; or a halogen such as methylene chloride. A hydrocarbon solvent or a butadiene compound as a monomer can be used as the solvent.

As a polymerization method, either a batch type or a continuous type polymerization is possible.

The polymerization temperature can range from -50 ° C to 200 ° C, but is particularly preferably between -20 ° C and 100 ° C.

<Examples> Next, the effects of the present invention will be specifically described with reference to examples of the present invention, but the present invention is not limited to these examples.

The microstructure of the polymer obtained in the butadiene polymerization in the examples was determined by the Morero method by infrared analysis (La Chimica e Industria, published in 1959, vol. 41, p. 758) and ^It was determined from the intensity ratio of the signals in the ¹³ C NMR spectrum. Assignment of NMR spectrum is polymer 1
Published in 972, Vol. 29, pages 397-402.
Infrared analysis was performed using an IR-810 manufactured by Hitachi Spectroscopy, and NMR measurement was performed using a JEOL FX-100 spectrometer.

Examples -1 to 10 1) Reaction of catalyst component (A) with catalyst component (C) (1) 2,2'-
0.9 mmol of dihydroxy-3,3'-di-t-butyl-5,5'dimethyldiphenylsulfide was taken, and after purging with argon, 50 ml of dried n-butyl ether was added, followed by stirring and dissolving. 0.9 mmol of tetraisopropoxy titanium
Was added. The reaction was carried out at 25 ° C. with stirring for 2 hours. Thereafter, the mixture was allowed to stand, the supernatant was removed, and the precipitate was collected and washed. The product thus obtained is used as a catalyst component.

(2) As the catalyst component (A), a catalyst component obtained by exactly the same method except that 0.9 mmol of titanium tetrachloride was used instead of tetraisopropoxytitanium in (1) is used as the catalyst component.

(3) A catalyst component obtained by the same method as (1) except that 0.9 mmol of titanium tetrabromide was used in place of tetraisopropoxytitanium in (1) as the catalyst component (A).

(4) As the catalyst component (C), 2,2'-dihydroxy-3,
A catalyst component obtained by the same method as in (1) except that 0.9 mmol of 3'-di-t-butyl-5,5'dimethyldiphenylmethane was used.

(5) A catalyst component obtained by exactly the same method as (4) except that 0.9 mmol of titanium tetrachloride was used as the catalyst component (A).

(6) As the catalyst component (C), 2,2'-dihydroxy-3,
The catalyst component was obtained by the same method as in (1) except that 0.9 mmol of 3'-di-t-butyl-5,5'dimethyldiphenylsulfide was used.

(7) A catalyst component obtained by the same method as in (6) except that 0.9 mmol of titanium tetrachloride was used as the catalyst component (A).

(8) A catalyst component obtained by the same method as in (1) except that 0.9 mmol of 2,2'-dihydroxydiphenyl sulfide is used as the catalyst component (C).

(9) A catalyst component obtained by the same method as (8) except that 0.9 mmol of titanium tetrachloride was used as the catalyst component (A).

(10) Tetrabutoxy titanium 0.9m as catalyst component (A)
A catalyst component was obtained by the same method as (1) except that mol was used.

2) Polymerization of 1,3-butadiene After replacing a 100-ml three-necked flask equipped with a stirrer with argon, 0.009 mmol of the obtained catalyst component was added, and 20 ml of toluene was added to dissolve the catalyst. After dissolution, 1.7 mmol of diethylaluminum chloride (hereinafter abbreviated as DEAC) was added. After stirring at 30 ° C. for 10 minutes, 1,3-butadiene was pressed at 0.03 kg / cm ² (gauge pressure) at 30 ° C. to initiate polymerization. Polymerization was carried out for 3 hours at 30 ° C. with stirring while maintaining the pressure of 1,3-butadiene at 0.03 kg / cm ² , the reaction was stopped with 10 ml of isobutanol, and the polymer was precipitated with 300 ml of 1N HCl / methanol. . After the polymer was separated by filtration, the polymer was dried under reduced pressure at 60 ° C. for 2 hours, and the yield was measured.

 The results are shown in Table 1.

Comparative Example 1 The polymerization of 1,3-butadiene was carried out in the same manner as in Example 3 except that dicyclopentadienyl titanium chloride (Cp ₂ TiCl ₂ , hereinafter abbreviated as DPTC) was used instead of the catalyst component. Performed, but no polymer was obtained.

 The results are shown in Table 1.

Examples 11 to 14 In Examples 1 to 10, the prepared catalyst component or the second component was replaced with ethyl aluminum sesquichloride (hereinafter abbreviated as ESC) or ethyl aluminum dichloride (hereinafter abbreviated as EADC) instead of DEAC. Except for using the proportions shown in the table, 1,3
-Polymerization of butadiene was carried out. The results are shown in Table 2.

Examples 15 to 19 1,3-butadiene was polymerized by using or as a catalyst component and changing polymerization conditions as shown in Table 3.

Table 3 also shows the microstructure of the obtained polybutadiene.

The trans content can be controlled by selecting appropriate polymerization conditions in the range of 50% or more, and the vinyl content can be reduced to zero.

Butadiene was polymerized under different polymerization conditions using or as a catalyst. As an example, the use of or as a catalyst was shown, but it was found that the cis content could be 90% or more depending on the polymerization conditions even when using a catalyst or.

Comparative Example-1 Instead of the catalyst component, tetrabutoxy titanium (hereinafter referred to as
Polymerization of butadiene was carried out in the same manner as in Example 1 except that TBT was used, but only a trace amount of polymer was obtained.

<Effect of the Invention> A highly active butadiene is obtained using a catalyst system comprising a transition metal compound represented by the general formula M (R) _l (OR ') mXn- (l + m), organoaluminum and an organic compound having at least two hydroxyl groups. The compound can be polymerized. In addition, the trans polymer content could be controlled within the range of 50% or more, and the vinyl content could be reduced to 0%.

[Brief description of the drawings]

FIG. 1 is a flowchart for helping the understanding of the present invention. This flowchart is a representative example of the embodiment of the present invention, and the present invention is not limited to this.

Continuation of front page (72) Inventor Kazuhiro Watanabe 5-1 Anesaki Beach, Ichihara-shi, Chiba Sumitomo Chemical Co., Ltd. (56) References JP-A-1-254713 (JP, A) JP-A-3-188109 (JP) , A) (58) Field surveyed (Int. Cl. ⁶ , DB name) C08F 4/60-4/70 C08F 36/06 C08F 136/06 C08F 236/06

Claims (24)

(57) [Claims] 1. A catalyst component (A) having the general formula M (R) _L (O
R ′) _m X _{n- (L + m)} (where M is titanium, zirconium,
A transition metal atom selected from hafnium or vanadium, R and R 'represent a hydrocarbon group having 1 to 20 carbon atoms, and X represents a halogen atom. L, m, n is L ≧ 0, m ≧ 0, n− (L + m) ≧ 0
Represents a number. n corresponds to the valence of the transition metal. ) And a catalyst component (B): General formula AlR ¹ _a X ′ _3-a (R ¹ has 1 to ¹ carbon atoms)
20 hydrocarbon groups, X 'is a halogen atom, a is 1≤a≤3
And a catalyst component (C): an organic compound having at least two hydroxyl groups represented by the general formula I, II, III, IV, V or VI (Wherein R ″, R, is a hydrocarbon group having 1 to 20 carbon atoms, Y is a hydrocarbon group having 1 to 20 carbon atoms, (R ⁶ represents hydrogen or a hydrocarbon group having 1 to 6 carbon atoms.)
Represents Here, R ² , R ³ , R ⁴ and R ⁵ represent a hydrocarbon group having 1 to 20 carbon atoms, a hydroxyl group, a nitro group, a nitrile group, a hydrocarboxy group or a halogen atom. In this case, R ² , R ³ , R ⁴ and R ⁵ may be the same or different. n 'is 0
Or, it is an integer of 1 or more and represents the number of repetitions of the unit Y. Y, y ', y ", y, z, z', z" and z represent the number of substituents bonded to the aromatic ring. y, y ', z and z' are 0 or an integer from 1 to 4, and y ", z" is 0 or 1.
And y and z represent 0 or an integer of 1 to 3. ) A catalyst for the production of trans 1,4 polybutadiene. 2. The catalyst component (A) according to claim 1, wherein said catalyst has a general formula M (R)
M of the transition metal compounds represented by _{L (OR ') m X n-} (L + m)
The catalyst according to claim 1, wherein is titanium or zirconium. 3. The catalyst component (A) according to claim 1, wherein said catalyst has a general formula M (R)
M of the transition metal compounds represented by _{L (OR ') m X n-} (L + m)
Is titanium or zirconium, and L = 0, m> 0, and nm ≧ 0. 4. The catalyst component (A) according to claim 1, wherein the general formula M (R)
_{L (OR ') m X n-} (L + m) is the catalyst of claim 1 is titanium tetrachloride or zirconium tetrachloride. 5. The catalyst component (A) according to claim 1, wherein said catalyst has the general formula M (R)
_L (OR ') catalyst according to claim _{1 m X n- (L + m} ) R and R' is an alkyl group or an aryl group. 6. The catalyst component (A) according to claim 1, wherein R is a methyl, ethyl, phenyl or benzyl group and R 'is an n-propyl, isopropyl, n-butyl, t-butyl or phenyl group. The catalyst as described. 7. A catalyst component (C) comprising a compound of the general formula I or II
The catalyst according to any one of claims 1, 2, 3, 4, 5, and 6, wherein the compound represented by the following formula is used. 8. The catalyst component (C), wherein the compound represented by the general formula V or VI
A compound represented by the formula (1), (2), (3), (4), (5), (6) or (7)
The catalyst according to the above. 9. The catalyst component (C) has a general formula The catalyst according to claim 8, wherein a compound represented by the following formula is used. 10. The catalyst according to claim 9, wherein a compound in which y, y, z and z are 1 is used in the catalyst component (C). 11. The catalyst component (C) wherein n 'is 1 and Y
11. The catalyst according to claim 8, 9 or 10, wherein a compound is a hydrocarbon group having 1 to 20 carbon atoms. 12. The catalyst according to claim 8, 9 or 10, wherein in the catalyst component (C), a biphenyldiol or a binaphthol compound wherein n 'is 0 is used. 13. The catalyst component (C) wherein n 'is 1 and Y
But 11. The catalyst according to claim 8, wherein the compound is: 14. The catalyst component (C) wherein n 'is 1 and Y
14. The catalyst according to claim 13, wherein the compound is -S-. 15. The catalyst according to claim 7, wherein in the catalyst component (C), R ″, R is a methylene, ethylene, ethylidene or isobutylidene group. 16. The catalyst according to claim 7, wherein in the catalyst component (C), R ² , R ³ , R ⁴ or R ⁵ is an alkyl group or an aryl group having 1 to 10 carbon atoms. 17. In the catalyst component (C), R ² , R ³ , R ⁴ or R ⁵ is methyl, ethyl, n-propyl, isopropyl, n-
13. The catalyst according to claim 12, which is a butyl, isobutyl or t-butyl group. 18. The catalyst according to claim 7, wherein 2,4-dihydroxypentane or catechol is used as the catalyst component (C). 19. The catalyst according to claim I2, wherein 2,2'-biphenyldiol or 1,1'-biphenyl-2-naphthol is used as the catalyst component (C). 20. As the catalyst component (C), 4,4 ', 6,6'-
Tetra-t-butyl-2,2'-methylenediphenol,
4,4'-dimethyl-6,6'-di-t-butyl-2,2'-methylenediphenol, 4,4 ', 6,6'-tetramethyl-2,
15. The catalyst according to claim 14, wherein 2'-isobutylidene diphenol is used. 21. The catalyst according to claim 14, wherein 2,2'-dihydroxy-3,3'-di-tert-butyl-5,5'-dimethyldiphenylsulfide is used as the catalyst component (C). 22. Catalyst component (A): General formula M (R) _L (OR ′)
_m X _{n- (L + m)} (where M is a transition metal atom selected from titanium, zirconium, hafnium or vanadium,
R and R 'each represent a hydrocarbon group having 1 to 20 carbon atoms, and X represents a halogen atom. L, m, n represent numbers satisfying L ≧ 0, m ≧ 0, n− (L + m) ≧ 0. n corresponds to the valence of the transition metal. )
And a transition metal compound represented by the following formula: Catalyst component (B): General formula AlR ¹ _a Z _3-a (R ¹ has 1 to 20 carbon atoms)
A is a halogen atom, and a is a number satisfying 1 ≦ a ≦ 3. And a catalyst component (C): an organic compound having at least two hydroxyl groups represented by the general formula I, II, III, IV, V or VI (Wherein, R ″, R is a hydrocarbon group having 1 to 20 carbon atoms, Y is a hydrocarbon group having 1 to 20 carbon atoms, (R ⁶ represents hydrogen or a hydrocarbon group having 1 to 6 carbon atoms.)
Represents Here, R ² , R ³ , R ⁴ and R ⁵ represent a hydrocarbon group having 1 to 20 carbon atoms, a hydroxyl group, a nitro group, a nitrile group, a hydrocarboxy group or a halogen atom. In this case R ² ,
R ³ , R ⁴ and R ⁵ may be the same or different.
n ′ is 0 or an integer of 1 or more, and represents the number of repetitions of the unit Y. Y, y ', y ", y, z, z', z" and z represent the number of substituents bonded to the aromatic ring. y, y ′, z
And z 'is 0 or an integer from 1 to 4, y ", z" is 0 or an integer from 1 to 2, and y and z are 0 or an integer from 1 to 3. A process for the selective production of trans 1,4 polybutadiene using a catalyst system comprising: 23. A catalyst of the general formula M (R) _L (O)
23. The method according to claim 22, wherein in the transition metal compound represented by R ′) _m X _{n- (L + m)} , M is titanium or zirconium. 24. The catalyst according to claim 22, wherein a compound represented by the general formula I, II, V or VI is used as the catalyst component (C).
Item or the production method according to Item 23.