JPH0820548A - Method for producing biphenyl compound - Google Patents

Abstract

PURPOSE:To enable inexpensive and efficient production of biphenyls which is useful as a starting material for 4,4'-biphenyldi-carboxylic acid by alkylation of an alkylbenzene with a cyclohexene in the presence of hydrogen fluoride followed by dehydrogenation. CONSTITUTION:In the presence of hydrogen fluoride or hydrogen fluoride-boron trifluoride, an alkylbenzene is alkylated with a cyclohexene lower than 50 deg.C. The product, phenylcyclohexane derivative is subjected to dehydrogenation reaction in the presence of a catalyst (platinum on alumina) at 250-350 deg.C to give biphenyl. The cyclohexene and hydrogen fluoride are used in 0.01-0.95 mole and 0.01-50 moles amounts per mole of the alkylbenzene, respectively. The biphenyl is useful as a starting substance for 4,4'-biphenyldicarboxylic acid, a component of high-performance polyester and aramide resins.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a novel biphenyl compound. Biphenyl compounds have been particularly noted as a raw material for 4,4`-biphenyldicarboxylic acid, which is useful as a material for high-performance polyester resins or aramid resins having heat resistance and high strength.

[0002]

2. Description of the Related Art Various methods have been proposed for producing 4,4'-biphenyldicarboxylic acid. However, all the methods have drawbacks such as complexity or low yield, and it is difficult to be an economical manufacturing method. In Japanese Examined Patent Publication No. 20420/1992, 4-alkylbiphenyl is reacted with carbon monoxide in the presence of a hydrogen fluoride-boron fluoride catalyst to give 4-alkyl-4′-formylbiphenyl in high yield. A method for producing 4,4′-biphenyldicarboxylic acid, which is obtained and then oxidized with a gas containing molecular oxygen, has been proposed. 4-Methylbiphenyl, which is one of 4-alkylbiphenyls, is obtained by reacting biphenyl obtained by dimerizing benzene with carbon monoxide in the presence of a hydrogen fluoride-boron fluoride catalyst to give 4-biphenylaldehyde. , Hydrogenation and subsequent hydrocracking.

Biphenyl is produced by dimerizing benzene at a high temperature of 700 ° C. or higher, but the reaction rate cannot be increased in order to prevent the formation of a high boiling point tar component which is a by-product such as a trimer. Therefore, the advent of a method for producing a large amount of biphenyl at a low cost in a high yield is desired. In order to produce 4,4'-biphenyldicarboxylic acid using biphenyl as a raw material by applying the above-mentioned formylation reaction, the first step is formylation of biphenyl, and the second step is formylation of 4-methylbiphenyl, and twice. The formylation reaction is required. Therefore, it is necessary to use two formylation reactors or to increase the capacity of the reactors and perform formylation of biphenyl and 4-methylbiphenyl simultaneously in the same reactor, and a complicated separation and purification step is required. Become. Therefore, if a method for efficiently and inexpensively producing 4-methylbiphenyl can be established, the formylation reaction can be performed once and the productivity can be improved. Also, without using the formylation reaction,
If a method for efficiently producing 4'-dialkylbiphenyl can be established, it will be possible to directly oxidize this to produce 4,4'-biphenyldicarboxylic acid at low cost.

[0004]

As described above, in order to establish an economical production method of 4,4'-biphenyldicarboxylic acid, a biphenyl compound as a raw material, that is, biphenyl, 4-alkylbiphenyl and 4,4 It is necessary to develop a process for efficiently producing'-dialkylbiphenyl. The aim of the present invention is to develop an inexpensive and efficient industrial process for the production of these biphenyl compounds.

[0005]

Means for Solving the Problems The inventors of the present invention have earnestly studied a new method for producing a biphenyl compound as described above, and as a result, in the presence of a hydrogen fluoride catalyst or a hydrogen fluoride-boron fluoride catalyst, alkylbenzenes have been obtained. The present inventors have found that a biphenyl compound can be efficiently produced by alkylating a compound with cyclohexene to obtain a phenylcyclohexane derivative, and then dehydrogenating the compound to synthesize a biphenyl skeleton.

That is, according to the present invention, a phenylcyclohexane derivative is obtained by alkylating alkylbenzenes with cyclohexene in the presence of hydrogen fluoride or hydrogen fluoride-boron fluoride, and then dehydrogenates to synthesize a biphenyl skeleton. And a method for producing a biphenyl compound.

The alkylbenzenes used in the alkylation reaction in the present invention are preferably monoalkylbenzenes such as toluene, ethylbenzene and isopropylbenzene, and these compounds are industrially available in large quantities at low cost. In addition to this, alkylbenzenes having an alkyl group having 4 or more carbon atoms can be used, and a biphenyl compound can be synthesized using benzene having no alkyl group or xylene or trimethylbenzene which is polyalkylbenzene.

Cyclohexene is suitable as the cyclohexene used as the alkylating agent, and it is industrially available in large quantities at low cost. In addition to this, 4- having a methyl group
Methylcyclohexene, 3-methylcyclohexene, 2
-Methylcyclohexene, 4-ethylcyclohexene, 4-vinylcyclohexene and the like can also be used. Further, 4-cyanocyclohexene having a nitrile group and the like can also be used.

For example, when toluene is used as the alkylbenzenes and cyclohexene is alkylated at a reaction temperature of 50 ° C. or lower in the presence of a hydrogen fluoride catalyst or a hydrogen fluoride-boron fluoride catalyst, cyclohexyltoluene is obtained in a high yield. can get. In the presence of a hydrogen fluoride catalyst, a mixture of cyclohexyltoluene in which the ortho, meta and para positions are cyclohexylated with respect to the methyl group on the benzene ring is obtained. In the presence of the hydrogen fluoride-boron fluoride catalyst, the production of 1-cyclohexyl-3-methylbenzene in which the meta position is cyclohexylated is increased.

It is known that cyclohexenes undergo an isomerization reaction in the presence of an acid catalyst to form a 5-membered ring compound such as methylcyclopentane or methylcyclopentene. For example, when alkylation is carried out at a high temperature of 200 ° C. or higher using a solid acid catalyst, the yield of cyclohexyltoluene is low and the by-product of methylcyclopentyltoluene is remarkable. When alkylation is performed in the presence of a hydrogen fluoride catalyst or in the presence of a hydrogen fluoride-boron fluoride catalyst, the alkylation reaction proceeds even at a low temperature of 50 ° C. or lower, and the cyclohexene isomerization reaction caused at a high temperature is also caused. It never happens. Further, when the alkylation is carried out at a reaction temperature of 50 ° C. or lower, the production of high boiling by-products such as polyalkyl compounds is small and the production amount of monoalkyl compounds can be increased.

The temperature of the alkylation reaction is 50 ° C. or lower, preferably -20 to 10 ° C. for the above reasons. Even if the temperature is lower than -20 ° C, the reaction proceeds sufficiently, but this temperature range is preferable from the viewpoint of the capacity and economy of the refrigerator. 10
If the temperature exceeds ℃, by-product of methylcyclopentyltoluene and polyalkyl compound will increase and the yield will decrease.

The molar ratio of cyclohexenes to alkylbenzenes in this reaction can be selected from a wide range of 0.01 to 100, but in order to obtain a monoalkyl product in a high yield, the reaction is carried out under an excess of alkylbenzenes. Is preferred. From the viewpoint of recovery of unreacted raw materials, space-time yield, operability, etc., the amount of cyclohexenes used is preferably in the range of 0.05 to 0.95 times the molar amount of alkylbenzenes. Even if a polyalkyl compound is produced as a by-product during the alkylation reaction, the polyalkyl compound can be transalkylated to be converted into a monoalkyl compound.

The amount of hydrogen fluoride as a catalyst can be selected from a wide range of 0.001 to 1000 times mol relative to the alkylbenzenes. When the amount of hydrogen fluoride increases, the reaction rate increases, but a large amount of energy is required to separate it from the raw materials and products. The range of 0.01 to 50 times mol is sufficient for economically carrying out on an industrial scale.

The alkylation reaction proceeds even if boron fluoride is present together with hydrogen fluoride. When hydrogen fluoride is used in an amount equal to or more than the cyclohexene and boron fluoride is used in an amount equal to or more than the cyclohexene, the cyclohexyl-alkylbenzenes particularly produced are only the meta form.

The alkylation reaction is a batch reaction in which alkylbenzenes, cyclohexenes and a catalyst are charged in a lump: a batch reaction in which alkylbenzenes and a catalyst are charged in a reactor and then cyclohexenes are sequentially added: Any method such as a continuous method in which the cyclohexenes and the catalyst are continuously supplied and the product is continuously extracted can be used.

The extracted alkylation reaction product liquid can be separated into an unreacted starting material, a target product, and a by-product polyalkyl compound by distillation after recovering the catalyst by, for example, a thermal decomposition method. The catalyst can be recovered and reused, and the unreacted raw material and polyalkyl compound can be recycled to the alkylation reactor.

The cyclohexyl-alkylbenzenes obtained by the alkylation reaction can be directly converted into a biphenyl derivative by a dehydrogenation reaction. Especially 4-
When an alkyl biphenyl is to be obtained, the ortho and meta isomers are isomerized to the para isomer and then dehydrogenated to give 4-
It can be converted to an alkyl biphenyl.

Platinum or palladium is used as the catalyst for the dehydrogenation reaction. The platinum and palladium are used in the form of being supported on a metal black or a carrier. As the carrier, activated carbon, silica, alumina, silica-alumina, titania, etc. are preferably used.

The dehydrogenation reaction can be carried out in a liquid phase or a gas phase by either a continuous method or a batch method, but a gas phase fixed bed flow reaction method is simple. The reaction is 250-35 under normal pressure.
It is performed in the temperature range of 0 ° C. This reaction is carried out under conditions such that the starting material cyclohexyl-alkylbenzenes and the product biphenyls are substantially in the gas phase. As a method for maintaining the gas phase, there are a method of carrying out the reaction at a temperature equal to or higher than the boiling point of the raw material, a method of carrying out the reaction by lowering the partial pressure of the raw material using a diluent. Examples of the diluent medium include inert gases such as nitrogen, argon, and helium, and aliphatic hydrocarbons and aromatic hydrocarbons that become a gas under the reaction conditions.

When the cyclohexyl-alkylbenzenes used as the raw material for the dehydrogenation reaction are in the ortho or meta form, or when the alkylation reaction is carried out using methylcyclohexene or the like as an alkylating agent, 4-alkylbiphenyl or 4, Alkyl biphenyls other than 4'-dialkyl biphenyl are produced, but these are isomerized to form 4 or 4-4 '.
It can be converted into the body and used.

[0021]

EXAMPLES Next, the present invention will be specifically described with reference to Examples.
However, the present invention is not limited to these examples.
In the following Examples, Examples 1 to 5 and Comparative Example 1 are for an alkylation reaction, and Examples 6 to 10 are for a dehydrogenation reaction.

Example 1 (Alkylation reaction) Toluene 6 was placed in a 300 ml stainless steel autoclave.
0.0g and 10.7 g of cyclohexene were charged and cooled to -10 ° C with stirring. 39.1 g of hydrogen fluoride was introduced while paying attention to heat generation, and the reaction was carried out for 15 minutes. The reaction temperature at this time was -10 to -1.2 ° C. After the reaction, the produced liquid was extracted into ice water, and the oil layer was washed with water and an alkaline aqueous solution for analysis. The results are shown in Table 1. Unreacted cyclohexene was not observed, and monocyclohexyltoluene was obtained at a yield of 96.84% and dicyclohexyltoluene at a yield of 3.16%. The production ratio of each isomer in monocyclohexyltoluene was ortho-form-33.0%, meta-form-18.3%, and para-form-48.7%.

Examples 2 to 4 The procedure of Example 1 was repeated except that the amounts of hydrogen fluoride and boron fluoride used as catalysts and the reaction temperature were changed. The results are shown in Table 1.

Comparative Example 1 Example 1 was repeated except that the reaction temperature was 55 to 65 ° C. The results are shown in Table 1. In this result, as the reaction temperature increases, the light-boiling product containing methylcyclopentyltoluene as the main component and the high-boiling product containing dicyclohexyltoluene as the main component increase, and the yield of monocyclohexyltoluene is 80 at 50 ° C. or higher. % Or less.

[0025]

[Table 1] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Molar ratio HF / Tol 3.0 6.0 3.1 6.0 3.0 BF ₃ / Tol 0.0 1.5 0.18 0.0 0.0 CHEN / Tol 0.2 0.2 0.2 0.2 0.2 Reaction temperature (° C ) -10 to -1.2 -8.7 to -0.3 -5.9 to 4.1 27 to 38 55 to 65 Yield Light boiling point product 0.0 0.0 0.0 5.25 10.25 (%) Monoalkyl compound 96.84 94.84 92.26 83.01 74.18 High boiling point product 3.16 5.16 7.74 11.74 15.57 Monoalkyl isomer distribution (%) o-body 33.0 0.0 0.0 30.7 31.6 m-body 18.3 99.6 95.3 16.4 17.2 p-body 48.7 0.39 4.68 52.9 51.2 (usage code) Tol: toluene, CHEN: cyclohexene light boiling point product : Methylcyclopentyltoluene is the main component Monoalkyl compound: Cyclohexyltoluene High-boiling product: Dicyclohexyltoluene is the main component

Example 5 12. Methyl 4-methylcyclohexene was used as an alkylating agent.
Example 2 was repeated except that 5 g was used. Table 2 shows the results.

[0027]

[Table 2] (Usage code) Tol: Toluene, CHEN: 4-methylcyclohexene Light boiling point product: Main components are dimethylcyclopentyltoluene and 1-methyl-metatoluyl-cyclohexane Monoalkyl compound: Methyl-metatoluylcyclohexyne 3,3 'compound: 3 -Methyl-metatoluyl-cyclohexane 3,4 'form: 4-methyl-metatoluyl-cyclohexane

Example 6 (Dehydrogenation reaction) 0.5% by weight platinum / particles of 0.5-1.0 mm in a glass reaction tube having an inner diameter of 13 mmφ and a length of 350 mmL.
4.0 g of activated carbon catalyst was loaded. The top of the catalyst was filled with glass beads at a height of 200 mm, and the reaction tube was heated to 280 ° C. The product liquid in Example 1 was subjected to simple distillation to separate a monocyclohexyltoluene fraction, and then a 33% n-heptane solution of this cyclohexyltoluene was supplied from above the glass beads at a supply rate of 7.0 g / hour for dehydrogenation reaction. I went. When the product liquid was analyzed by gas chromatography, the reaction rate of cyclohexyltoluene was 9
The reaction proceeded quantitatively with 9.5% and a selectivity to methylbiphenyl of 99.9%. The ratio of 2-methylbiphenyl in the generated methylbiphenyl is 33.0%,
The proportion of 3-methylbiphenyl was 18.3%, and the proportion of 4-methylbiphenyl was 48.7%, which were the same as the ortho, meta, and para isomer ratios in the starting material cyclohexyltoluene.

Example 7 The same as Example 6 except that 1.0 wt% palladium / activated carbon was used as a catalyst, the cyclohexyltoluene obtained in Example 2 was used as a raw material, and the reaction was carried out in the absence of a diluent. did. As a result, the reaction rate of cyclohexyltoluene is 98.5% and the selectivity to methylbiphenyl is 99.8%.
The ratio of 3-methylbiphenyl in the produced methylbiphenyl was 99.6%.

Example 8 A reaction was carried out in the same manner as in Example 6 except that 1.0% by weight platinum / alumina was used as a catalyst. As a result, the reaction rate of cyclohexyltoluene was 99.3% and the selectivity to methylbiphenyl was 99.8%.

Example 9 The reaction was performed in the same manner as in Example 6 except that 1.0% by weight platinum / silica was used as the catalyst. As a result, the reaction rate of cyclohexyltoluene was 99.4% and the selectivity to methylbiphenyl was 99.8%.

Example 10 A mixture of 3-methyl-metatoluyl-cyclohexane and 4-methyl-metatoluyl-cyclohexane obtained by simple distillation of the product solution of Example 5 as a raw material (molar ratio 69: 3).
0.5% by weight of 33% toluene solution of 1) as a catalyst
The reaction was carried out in the same manner as in Example 6 except that platinum / activated carbon was used. As a result, the reaction rate of methyl-metatoluyl-cyclohexane was 99.9%, the selectivity of dimethylbiphenyl was 99.7%, the proportion of 3,3′-dimethylbiphenyl was 69%, and the proportion of 3,4′-dimethylbiphenyl. Was 31%.

[0033]

As is apparent from the examples, the target biphenyl compound can be obtained in an extremely high yield by the method of the present invention. The method of the present invention proposes a new inexpensive and efficient industrial production method of a biphenyl compound, which is a raw material of 4,4′-biphenyldicarboxylic acid, and its industrial significance is great.

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[Procedure amendment]

[Submission date] July 18, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0027

[Correction method] Change

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[0027]

[Table 2] (Usage code) Tol: Toluene, MCHEN: 4-methylcyclohexene Light boiling point product: Main components are dimethylcyclopentyltoluene and 1-methyl-metatoluyl-cyclohexane Monoalkyl compound: Methyl-metatoluylcyclohexane 3,3 'compound: 3- Methyl-metatoluyl-cyclohexane 3,4 'form: 4-methyl-metatoluyl-cyclohexane

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Claims (4)

[Claims] 1. A method for producing a biphenyl compound, which comprises alkylating alkylbenzenes with cyclohexene in the presence of hydrogen fluoride to obtain a phenylcyclohexane derivative, which is then dehydrogenated to synthesize a biphenyl skeleton. . 2. The method for producing a biphenyl compound according to claim 1, wherein the alkylation is carried out in the presence of hydrogen fluoride and boron fluoride. 3. The method according to claim 1, wherein the alkylation is performed at 50 ° C. or lower.
A method for producing a biphenyl compound. 4. The method for producing a biphenyl compound according to claim 1, wherein platinum and / or palladium is used as a dehydrogenation catalyst.