JPH07196737A - Production of cyclohexadiene - Google Patents

Abstract

PURPOSE:To obtain the subject polymer in high yield and in high polymerization degree, useful as a highly heat-resistant and high-rigidity polymer from a low- purity cyclohexadiene, by anionic polymerization of a raw material mixture comprising cyclohexane, benzene, specific amount of a cycloehexadiene, etc. CONSTITUTION:This polymer is obtained at low cost by anionic polymerization of a raw material mixture comprising cyclohexane, 10-80 (pref. 30-70)wt.% of 1,3-cyclohexadiene, benzene, methylcyclopentene and pref. 1-40wt.% of cyclohexane, pref. using an organoalkali metal amine complex, esp. an alkyllithium tetramethylethylenediamine complex as catalyst.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a process for producing a cyclohexadiene polymer useful as a polymer having high heat resistance and high rigidity.

[0002]

2. Description of the Related Art A method for producing a cyclohexadiene polymer using 1,3-cyclohexadiene as a raw material is a method by anionic polymerization using an organolithium compound as a catalyst (see British Patent Application No. 1,042,625). ,
J. Polym. Sci. , Pt. 3 , 1553 (19
65), Polym. Prepr. (Amer.Che
m. Soc. , Div. Polym. Chem. ) 1
2 , 402 (1971)) is known. Further, the present inventors have previously developed a method for producing a cyclohexadiene high polymer by anionic polymerization using an amine complex of an alkali metal (Japanese Patent Application No. 5-141281).

Further, the present inventors have proposed a method for producing a cyclohexadiene polymer having a high cis-1,4 bond ratio by coordination polymerization using a rare earth metal compound and alumoxane as a catalyst (see Japanese Patent Application No. 5-116604). ) Is also developing. However, all of the above methods are methods using 90% or more of high-purity 1,3-cyclohexadiene as a raw material, and methods of using low-purity 1,3-cyclohexadiene have not been known.

On the other hand, as a method for producing 1,3-cyclohexadiene, a method of dehydrating 2-cyclohexen-1-ol in the gas phase using an alumina catalyst (Ve
stsi Akad. Navuk Beloruss
k. SSR, Ser. Khim. Navuk, (2) 2
0-4 (1965)) and the same dehydration reaction method using an alumina-boria catalyst (Dokl. Akad.
Nauk. Belorussk. SSR14 (8), 7
34-7 (1970)) and the like. By these methods, 1,3-cyclohexadiene is obtained with an extremely high selectivity of 99% or more. However, as a method of obtaining 2-cyclohexene-1-ol which is a raw material of these methods, cyclohexene is oxidized with an organic peroxide to produce cyclohexene, 2-cyclohexene-1-ol.
-All, cyclohexene oxide, 2-cyclohexene-1-one, and cyclohexenyl hydroperoxide as a mixture (USSR SU1,133,
253 (1985)), and air-oxidizing cyclohexene to give cyclohexenyl hydroperoxide, which is reacted with cyclohexene to obtain a mixture of 2-cyclohexen-1-ol and cyclohexene oxide (see Japanese Patent Publication No. 45-40045). ), And a method of decomposing cyclohexenyl hydroperoxide with an aqueous alkali solution to obtain 2-cyclohexen-1-ol ([oxidation and reduction of organic compounds] published by Nankodo Co., Ltd., 1952, 51).
(Page) and the like, and a complicated method that requires complicated separation is required.

As a method for producing 1,3-cyclohexadiene, cyclohexene oxide is brought into contact with a metal oxide catalyst such as alumina, titania or zirconia by a gas phase pulse reaction system at 150 ° C. (Bull. Chem.
Soc. Jpn. , 49 (2), 563-564 (19
76)) has been reported. This method is a pulse reaction method and cannot be said to be an industrial production method. Moreover, the selectivity of 1,3-cyclohexadiene is as low as 56%, and the purity of 1,3-cyclohexadiene after removal of high boiling substances is high. Is not stated.

Similarly, as a method using cyclohexene oxide as a raw material, a method of dehydration reaction using a silica / titania or silica / titania / magnesia catalyst in a liquid phase (JP-A-57-26628) has been reported. ing. With this method, only a low selectivity of around 50%
3-Cyclohexadiene has not been obtained. These methods using cyclohexene oxide as a raw material cannot be said to be an industrial production method because of their low selectivity, and the production of cyclohexene oxide as a raw material is similar to the production method of 2-cyclohexene-1-ol described above. There is also a problem in that it involves a complicated process involving hexenyl hydroperoxide.

Further, USSR SU1,133,253
(1985), a mixture of cyclohexene, 2-cyclohexene-1-ol, cyclohexene oxide, 2-cyclohexene-1-one, and cyclohexenyl hydroperoxide obtained by oxidizing cyclohexene with an organic peroxide as it is in a gas phase. Describes a method of passing a mixture of 1,3-cyclohexadiene over clinoptilolite, a natural zeolite, at 270 to 300 ° C. However, the purity of cyclohexadiene obtained by this method is extremely low at around 30%,
In order to increase the purity, 1,3-cyclohexadiene was dimerized from the obtained product and separated from other products,
A complicated purification method of decomposing the dimer to return it to 1,3-cyclohexadiene is used.

USSR SU 1,074,853
(1984) describes a process for producing 1,3-cyclohexadiene by oxidative dehydrogenation of cyclohexene using a catalyst in which neodymium oxide is supported on natural zeolite. The cyclohexene conversion rate is 27% and the selectivity is 93%. 1,3-cyclohexadiene is obtained. However, in this method, benzene and methylcyclopentene are by-produced, and unreacted cyclohexene is also present. These by-products and cyclohexene are the target 1,3-
Since the boiling point of cyclohexadiene is extremely close to that of cyclohexadiene, it cannot be separated by ordinary distillation separation, and the complicated separation method of dimerization / decomposition described above is required.

As described above, in the method for producing 1,3-cyclohexadiene, the method via 2-cyclohexen-1-ol, which gives a highly pure product, requires a long process and the separation of by-products and co-products formed on the way is complicated. In addition, the method of directly subjecting the cyclohexene oxidation product, which has a short process, to the gas phase dehydration reaction and the method of oxidative dehydrogenation of cyclohexene are low in the purity of 1,3-cyclohexadiene obtained. However, there was a problem that complicated purification was required.

[0010]

The conventional method for producing a cyclohexadiene polymer is to use 90% or more of high-purity 1,3-cyclohexadiene as a raw material. Was not known. On the other hand, as a method for producing the raw material 1,3-cyclohexadiene, several production steps must be carried out in order to obtain a high-purity product, and a high-purity method can be obtained by a simple short production process. However, there is a problem in that a complicated purification process is required because the above is not obtained.

Therefore, a method for producing a cyclohexadiene polymer using low-purity 1,3-cyclohexadiene as a raw material, which is obtained from a simple production process industrially, has been desired.

[0012]

Means for Solving the Problems The inventors of the present invention have made earnest studies to solve the above problems, and as a result, by applying an anionic polymerization system as a polymerization system, It was found that a cyclohexadiene polymer can be obtained from 3-cyclohexadiene in a high yield, and the present invention has been completed.

That is, the present invention relates to cyclohexene, 1,
In producing a cyclohexadiene polymer by anionic polymerization from a mixture containing 3-cyclohexadiene, benzene and methylcyclopentene, the content of 1,3-cyclohexadiene in the raw material mixture is 10 to 80% by weight. Is a method for producing a cyclohexadiene polymer.

According to the method of the present invention, even if cyclohexene, benzene or methylcyclopentene is contained in the raw material, there is no problem. Therefore, it is necessary to increase the purity of 1,3-cyclohexadiene by further complicated purification of the raw material. There is no. Next, the present invention will be described in more detail. The raw material mixture of the present invention is a mixture containing cyclohexene, 1,3-cyclohexadiene, benzene and methylcyclopentene. The composition of these mixtures varies depending on the production method and conditions of the raw material mixture, but the content of 1,3-cyclohexadiene in the mixture is in the range of 10 to 80% by weight, preferably in the range of 20 to 75% by weight, More preferably 30 to 7
It is in the range of 0% by weight.

When the content is less than 10% by weight, the polymerization reaction itself is not adversely affected, but the productivity is lowered, which is not preferable, and when it exceeds 80% by weight, 1,3-cyclohexyl as a raw material is used. It is not preferable because the manufacturing method of hexadiene becomes complicated. The raw material mixture of the present invention may contain various aliphatic hydrocarbons, alicyclic hydrocarbons and aromatic hydrocarbons derived from the method for producing the raw material mixture, in addition to the above four components.

Examples of the above hydrocarbon include cyclohexane. As an industrial production method of cyclohexene, which is mainly used as a raw material for producing 1,3-cyclohexadiene, a production method by partial hydrogenation of benzene has recently been developed (see Japanese Patent Publication No. 3-5370 and Japanese Patent Publication No. 35299). However, cyclohexane is always a by-product in this method. Further, in order to increase the selectivity of cyclohexene, the conversion rate of benzene needs to be suppressed to about 50%, so that the cyclohexene obtained by this method is a mixture of benzene and cyclohexane. However, since the boiling points of benzene, cyclohexene, and cyclohexane are very close to each other, ordinary distillation separation is not possible. Therefore, a special extraction solvent is used for the separation of cyclohexene from this mixture (see Japanese Patent Publication No. 30575/1991). ) Is used. Therefore, there is a problem that the operation for separating cyclohexene is complicated and the separation cost is high. In that respect, it is preferable to include cyclohexane in the 1,3-cyclohexadiene because it is possible to reduce the cost for separating cyclohexene by going back to the raw material.

When cyclohexane is contained in the raw material mixture of the present invention, its content is desirably in the range of 1 to 40% by weight, preferably 2-35% by weight, more preferably 5 to 30% by weight. The raw material mixture of the present invention may contain various oxygen-containing compounds derived from the production method of the raw material mixture as impurities, but among the oxygen-containing compounds, alcohols, aldehydes, ketones, carboxylic acids, esters, acetals, ketals, etc. It is necessary to reduce the content of the compound that becomes a polymerization catalyst poison in (2) as much as possible. In this case, the content of these oxygen-containing compounds is 0.5% by weight or less, preferably 0.1.
It should be below 1% by weight, more preferably below 0.05% by weight.

The method for producing the raw material mixture of the present invention is as follows:
Various manufacturing methods can be considered, but they need to be simple. In that respect, the above-mentioned method for oxidative dehydrogenation of cyclohexene (U
SSR SU1,074,853 (1984)) and a method of directly subjecting a cyclohexene oxidation product to a gas phase dehydration reaction (USSR SU1,133,253 (198).
5)) is preferred.

Cyclohexene, 1,3-in the present invention
An anionic polymerization system is essential as a polymerization method for producing a cyclohexadiene polymer from a mixture containing cyclohexadiene, benzene and methylcyclopentene. Cyclohexene coexisting when a coordination polymerization system is used as the polymerization system,
The polymerization catalyst is poisoned by benzene and shows almost no polymerization activity. On the other hand, it was found that the influence of these coexisting compounds was very small in the anionic polymerization system.

As the anionic polymerization catalyst in the present invention, an alkali metal or an organic alkali metal compound is used, but an organic alkali metal compound is preferable, and an organic lithium compound is particularly preferable. Examples of the organolithium compound include alkyllithium such as methyllithium, ethyllithium, propyllithium, and butyllithium, and polar groups (RO-, R ₂ N-, 2-oxazolyl) having an unshared electron pair that can be further coordinated with alkyllithium. Group etc .: R represents an alkyl group) and an alkyllithium complex obtained by adding a compound having Among them, the alkyllithium complex is preferable, and the complex obtained by using a tertiary amine as a coordination compound is more preferable.

The tertiary amines include tetramethylethylenediamine (TMEDA) and diazabicyclo [2,2].
2,2] octane (DABACO) and the like can be mentioned,
Among them, tetramethylethylenediamine is preferable. These compounds may be one kind or a mixture of two or more kinds, if necessary.

The method for synthesizing the complex compound of an organic alkali metal is not particularly limited, and conventionally known techniques can be used. For example, a method of dissolving an organic alkali metal in an organic solvent and adding a solution of a compound serving as a ligand thereto, or a method of dissolving a compound serving as a ligand in an organic solvent and adding a solution of the organic alkali metal thereto And the like.

The amount of the polymerization catalyst used in the present invention varies depending on the kind of the catalyst and the reaction conditions, but it is 10 ^-6 mol to 1 as a metal atom per 1 mol of 1,3-cyclohexadiene.
It is in the range of 0 ^-1 mol, preferably 10 ^-5 mol to 10 ^-2
It is in the molar range. Examples of the method for producing the polymer of the present invention include bulk polymerization or solution polymerization. In the case of solution polymerization, the raw material mixture itself or a solvent may be used. However, even when a solvent is used, the content of 1,3-cyclohexadiene in the mixture containing the solvent is 1
It must be 0% by weight or more.

As the polymerization solvent when a solvent is used, normal pentane, normal hexane, normal heptane,
Examples thereof include aliphatic hydrocarbons such as cyclohexane and decalin, alicyclic hydrocarbons, aromatic hydrocarbons such as benzene, toluene, and xylene. The polymerization temperature in the present invention is appropriately selected depending on the catalyst, the concentration of 1,3-cyclohexadiene and the like, but is approximately -100 to 150 ° C, preferably -80 to 100 ° C, more preferably -50 to 80 ° C.
It is in the range of ° C.

The polymerization reaction can be carried out by either a batch method or a continuous method. The cyclohexadiene polymer obtained in the present invention means a polystyrene-based number average molecular weight of 1,000 or more, preferably 5,000 or more, more preferably 10,000 or more, and the bonding mode in the polymer is 1,2-bond. Even 1,4-
It may be a combination.

After the polymerization reaction achieves a predetermined polymerization rate, a known terminal modifying agent or terminal branching agent, a coupling agent, a polymerization terminator, a polymerization stabilizer, an antioxidant and the like are added to the reaction system, if necessary. In addition to the above, the polymer can be recovered by known desolvation and drying operations such as steam stripping drying and heat drying in the production of general conjugated diene-based polymers.

Further, the cyclohexadiene polymer of the present invention can be subjected to hydrogenation, halogenation and the like, if necessary, and further, carboxyl group, hydroxyl group, epoxy group, amino group, oxazoline group, alkoxy group. Modification with a polar group such as a group is also possible. In particular, hydrogenation is an extremely effective method for increasing the heat resistance and rigidity of the polymer. In the case of hydrogenation, the polymer may be directly used without being separated from the polymerization system, or may be separated and used in another solvent system. When hydrogenating without separating from the polymerization system, some or all of cyclohexene and benzene in the raw material mixture remaining after the polymerization become cyclohexane, and some or all of methylcyclopentene become methylcyclopentane. . Especially when all of them are cyclohexane and methylcyclopentane, the boiling points of cyclohexene, benzene and methylcyclopentene are so close that normal distillation separation is not possible, whereas cyclohexane and methylcyclopentane have a large difference in boiling point, so distillation separation is difficult. This is advantageous in that it is possible (see Japanese Patent Laid-Open No. 3-287548).

After polymerizing by the method of the present invention, when the polymer is removed, cyclohexene, benzene, methylcyclopentene and, if necessary, cyclohexane in the raw materials remain. These mixtures can be separated as needed and recycled to the production process of each raw material. However, in the case of separation, since the boiling points of the respective components are extremely close to each other as described above, it is necessary to use the extractive distillation method (see Japanese Patent Publication No. 30575/1990).

For example, when benzene is circulated in the step of partially hydrogenating benzene which is one of the cyclohexene production methods, a polar solvent such as dimethylacetamide is used as an extraction solvent to prepare a mixture of benzene, cyclohexene, cyclohexane and methylcyclopentene. Can be divided into or,
When cyclohexene is circulated in the production process of 1,3-cyclohexadiene, a mixture of the above cyclohexene, cyclohexane and methylcyclopentene is further used as an extraction solvent with a polar solvent such as dimethylacetamide to give a mixture of cyclohexene, cyclohexane and methylcyclopentene. Can be divided.

When benzene and cyclohexene are separated and recovered, it is extremely advantageous that the present invention separates and removes 1,3-cyclohexadiene as a polymer. This is because it is extremely difficult to separate 1,3-cyclohexadiene from benzene and cyclohexene by extractive distillation. Therefore, in order to separate these components before the polymerization as in the conventional method, a complicated separation method called dimerization / decomposition was required. In that respect, the present invention can be said to be advantageous from the viewpoint of circulation and reuse of each component.

Further, in order to obtain high-purity cyclohexane from cyclohexane or methylcyclopentene after cyclohexene is separated, it is preferable to hydrogenate it to obtain a mixture of cyclohexane and methylcyclopentane, and then separate by distillation. (See Japanese Laid-Open Patent Publication No. 3-287548)

[0032]

EXAMPLES The present invention will be described in more detail below with reference to examples.

[0033]

Example 1 Oxidative dehydrogenation of cyclohexene was carried out under the following conditions using a catalyst in which 10 wt% neodymium oxide was supported on Na-type clinoptilolite. Temperature: 400 ° C. LHSV: 2.0 hr ⁻¹ Oxygen concentration: 6 vol% After 1 to 20 hours from the start of the reaction, the cyclohexene conversion rate is 50% and the 1,3-cyclohexadiene selectivity is 75%.
Met.

The resulting mixture was subjected to vacuum distillation to remove oxygen-containing compounds first, and then water was removed by azeotropic distillation to obtain a mixture having the following composition. 1,3-Cyclohexadiene: 37.0% by weight Cyclohexene: 50.0 〃 Benzene: 9.5 〃 Methylcyclopentenes: 3.0 〃 1,4-Cyclohexadiene: 0.5 〃 Using this mixture as a raw material Polymerization was performed by the following method.

A fully dried 100 ml pressure-resistant glass bottle was capped, and the inside was replaced with dry argon according to a conventional method. After injecting 10 g of the above mixture into a bottle, 0.10 mmol of a metal complex synthesized from normal butyl lithium and tetramethylethylenediamine was added as a polymerization catalyst, and polymerization was carried out at 25 ° C. for 2 hours. After the completion of the polymerization reaction, 10 g of methanol was added to stop the reaction.

Then, the light boiling components were evaporated by vacuum evaporation to recover a 1,3-cyclohexadiene polymer. The polymer obtained was washed with methanol and dried in vacuum at 50 ° C., and the yield determined by weight was 99.0%. or,
The number average molecular weight of the polymer was 40,000.

The light-boiling fraction recovered by evaporation under reduced pressure was further distilled to remove methanol, and the composition was as follows. Cyclohexene: 79.0% by weight Benzene: 15.1 〃 Methylcyclopentenes: 4.8 〃 1,4-Cyclohexadiene: 1.1 〃

[0038]

Example 2 Example 1 of Japanese Patent Publication No. 3-5370
According to the above, the partial hydrogenation reaction of benzene was carried out under the following conditions. Catalyst: Ru (OH) ₃ / Zn (OH) ₂ reduction product (Zn
7.4% by weight) 4.0 g water: 3200 g additive: zinc sulfate heptahydrate 144 g zirconium oxide 20 g benzene: 800 ml reaction temperature: 150 ° C. reaction pressure (hydrogen pressure): 50 kg / cm ² reaction time: 1 hour The reaction results are shown below.

Benzene conversion: 60%, cyclohexene selectivity: 80%, cyclohexane selectivity: 20% The obtained product solution was subjected to extractive distillation using dimethylacetamide as an extraction solvent, and dimethylacetamide containing benzene was extracted from the bottom of the column. A mixture of cyclohexene and cyclohexane was obtained from the top of the tower. The composition of this mixture was 81% by weight of cyclohexene and 19% by weight of cyclohexane.

Using this mixture as a starting material, oxidative dehydrogenation was carried out under the same conditions as in Example 1. The results of 1 to 20 hours after the start of the reaction are shown below. Cyclohexene conversion rate: 60
%, 1,3-Cyclohexadiene selectivity: 70% The obtained product liquid was first subjected to vacuum distillation to remove oxygen-containing compounds, and water was further removed by azeotropic distillation to obtain a mixture having the following composition.

1,3-Cyclohexadiene: 33.6% by weight Cyclohexene: 32.0 〃 Benzene: 10.0 〃 Cyclohexane: 20.0 〃 Methylcyclopentenes: 4.0 〃 1,4-Cyclohexadiene: 0. 4 〃 Polymerization was carried out by the following method using this mixture as a raw material.

A fully dried 1000 ml pressure-resistant glass autoclave was purged with dry argon. 200 g of the above mixture was charged, 1.0 mmol of a metal complex compound synthesized from normal butyl lithium and tetramethylethylenediamine was added as a polymerization catalyst, and the mixture was heated at 30 ° C.
Was polymerized for 2 hours. After the completion of the polymerization reaction, 1 g of methanol was added to deactivate the catalyst. Then, the light boiling components were removed by evaporation under reduced pressure to obtain a 1,3-cyclohexadiene polymer. After washing this polymer with methanol, 50
After drying at ℃, 65 g of a polymer was obtained. This yield is 96.
It was 7%.

The number average molecular weight of the polymer was 35,000. Furthermore, the light boiling fraction 130 recovered by evaporation under reduced pressure
g in a pressure-resistant autoclave, 10 g of Raney nickel catalyst was added, and 10 g of hydrogen was added under a hydrogen pressure of 30 kg / cm ^2.
The hydrogenation reaction was carried out at 0 ° C for 1 hour. The liquid composition after separating the catalyst from the product liquid is shown below.

Cyclohexane: 94.0% by weight Methylcyclopentane: 6.0 〃 Further, this mixture was subjected to distillation to obtain a mixture of methylcyclopentane: 50% by weight cyclohexane: 50% by weight from the top and a purity of 99. 8% cyclohexane was obtained.

[0045]

Comparative Example 1 Using the mixture obtained by distilling and purifying the product of oxidative dehydrogenation in Example 1 as a raw material, coordination polymerization was attempted under the following conditions. A 100 ml pressure-resistant glass bottle that had been sufficiently dried was capped, and the inside was replaced with dry argon according to a conventional method. After injecting 20 g of the above mixture into a bottle, 0.03 mmol of a rare earth metal compound, MMAO (n-heptane-soluble aluminoxane sold by Tosoh Akzo Co., Ltd.) was Al / Nd = 1000 element ratio, and ethyl aluminum was Cl / Nd. = 40 elements added to give a ratio of 3
Polymerization was carried out at ℃ for 5 hours. After the reaction, 10 g of methanol was added to deactivate the catalyst, followed by evaporation under reduced pressure. As a result, almost no polymer was obtained.

[0046]

According to the present invention, a polymer having a high degree of polymerization and a high yield can be obtained from low-purity 1,3-cyclohexadiene obtained by a simple method. This is extremely advantageous for industrial implementation.

Claims (4)

[Claims] 1. When producing a cyclohexadiene polymer by anionic polymerization from a mixture containing cyclohexene, 1,3-cyclohexadiene, benzene and methylcyclopentene, the content of 1,3-cyclohexadiene in the raw material mixture is 10 to 10. A method for producing a cyclohexadiene polymer, which is 80% by weight. 2. The raw material mixture contains 1 to 1 cyclohexane.
A method according to claim 1, characterized in that it comprises 40% by weight. 3. The method according to claim 1, wherein an organic alkali metal compound is used as a catalyst in the anionic polymerization. 4. The method according to claim 1, wherein an amine complex of an organic alkali metal is used as a catalyst in the anionic polymerization.