JPH0667874B2 - Process for producing 4'-hydroxybiphenyl-4-carboxylic acid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing 4'-hydroxybiphenyl-4-carboxylic acid. More specifically, the general formula (I) (Wherein R represents a lower alkyl group), which is obtained by reacting cyclohexanone-4-carboxylic acid ester represented by the formula (II) with phenol in the presence of an acid catalyst. (In the formula, R is the same as R in the formula (I).) 4,4
A mixture of -bis (4-hydroxyphenyl) -cyclohexanecarboxylic acid ester and 4,4-bis (4-hydroxyphenyl) -cyclohexanecarboxylic acid is then decomposed / dehydrogenated in the presence of a base to give 4'- The present invention relates to a novel method for producing hydroxybiphenyl-4-carboxylic acid.

4'-Hydroxybiphenyl-4-carboxylic acid is a very useful compound as a polymer raw material and a liquid crystal compound intermediate.

[Conventional technology]

There are few methods proposed as a method for producing 4'-hydroxybiphenyl-4-carboxylic acid, and only the following three methods are known.

(A) After p-phenylphenol was changed to p-methoxybiphenyl, 4-by-Friedel-Crafts reaction was performed.
A method for synthesizing methoxy-4'-acetobiphenyl, followed by oxidation to 4-methoxy-4'-carboxybiphenyl, and treating with hydrobromic acid to obtain the desired product [JAC of the Society (JAC
S., 58 , 1738)].

(B) A method of reacting p-iodobenzoic acid methyl ester with p-iodoanisole to obtain 4-methoxy-4'-carboxybiphenyl, and subsequently treating it in the same manner as in (a) to obtain the desired product [Britin of The Chemical
Society of Japan (Bull.Chem.Soc.Japan.
30 , 508-13, 1957)].

(C) Method for obtaining target compound by diazotization and hydrolysis of 4'-aminobiphenyl-4-carboxylic acid (FP73584
6) etc. are known.

[Problems to be solved by the invention]

However, in the conventional methods as described above, all the methods require expensive raw materials. Even in the method (a) in which p-phenylphenol, which is relatively inexpensive, is used as a starting material, it requires many steps, the raw material used in each step is expensive, and there are many problems in terms of wastewater treatment. Have. Therefore, inevitably obtained 4'-hydroxybiphenyl-4
It is no exaggeration to say that carboxylic acids have to be extremely expensive and that no industrial production method has been proposed yet.

[Means for solving problems]

The inventors of the present invention have conducted extensive studies to improve the drawbacks of the above conventional method, and as a result, the following formula (I ′) (In the formula, R represents a hydrogen atom or a lower alkyl group.) Cyclohexanone-4-carboxylic acid is used, and this is condensed with phenol to give a corresponding formula (II ′). To obtain 4,4-bis (4-hydroxyphenyl) -cyclohexanecarboxylic acid, which is then subjected to a dehydrogenation reaction to give 4'-hydroxyphenyl-
A novel manufacturing method for obtaining 4-carboxylic acids was previously found and applied.

After that, the inventors of the present invention further studied and used cyclohexanone-4-carboxylic acid ester as the compound of the formula (I ′), and the condensation reaction of this with phenol was carried out in the presence of an acid catalyst. At that time, as a by-product, the hydrolyzed 4,4-bis (4-hydroxyphenyl) -cyclohexanecarboxylic acid is mixed in the formula (II ′), but this does not need to be separated and the mixture It was found that the target product can be obtained in high yield when the decomposition dehydrogenation reaction is carried out in the presence of a base.

The present inventors have arrived at the present invention based on these findings.

In the method of the present invention, the cyclohexanone-4-carboxylic acid ester of the compound of formula (I) used as a raw material has the corresponding 4
-Hydroxybenzoic acid ester, that is, methyl 4-hydroxybenzoate, ethyl 4-hydroxybenzoate, 4-
It can be obtained by reacting propyl hydroxybenzoate or butyl 4-hydroxybenzoate with hydrogen in a solvent such as water, acetic acid or alcohol using a catalyst such as palladium supported on a carrier.

In the present invention, in order to obtain the compound of the formula (II), the cyclohexanone-4-carboxylic acid ester of the compound of the formula (I) is reacted with phenol in the presence of an acidic catalyst to give a corresponding 4,4- Bis (4-hydroxyphenyl) cyclohexanecarboxylic acid ester is obtained. At this time, a part is hydrolyzed to 4,4-bis (4-hydroxyphenyl) -cyclohexanecarboxylic acid by using an acid catalyst.

The amount of 4,4-bis (4-hydroxyphenyl) -cyclohexanecarboxylic acid, which is a by-product of hydrolysis, is about 10 to 30% by weight based on the compound of the formula (II) under normal conditions. Without being used, the mixture is directly subjected to the decomposition / dehydrogenation reaction. Of course, it does not matter if they are separated.

Examples of the acid catalyst used in the reaction of the compound of the formula (I) with phenol according to the present invention include hydrochloric acid, sulfuric acid, phosphoric acid, toluenesulfonic acid, BF ₃ , ZnCl ₂ , AlCl ₃ , SnCl 4 and a cation having a mobile acidic group. Examples include ion exchange resins. The amount of these catalysts used is in the range of 0.1 to 30 parts by weight per 100 parts by weight of cyclohexanone-4-carboxylic acid ester of formula (I).

It is also possible to increase the reaction rate by adding a co-catalyst, such as methyl mercaptan, ethyl mercaptan, n
-Propyl mercaptan, isopropyl mercaptan, n
Alkyl mercaptans such as -butyl mercaptan, isobutyl mercaptan, t-butyl mercaptan or high molecular weight alkyl mercaptans are active cocatalysts.

Further, other sulfur compounds such as hydrogen sulfide, thiophenol, thioalcohol, thioacid, polymer thioacetone, dialkyl sulfide and selenium compounds similar thereto can also be used.

The reaction of the present invention can be carried out using a solvent which does not adversely influence the reaction, such as aromatic hydrocarbon, chlorinated aliphatic hydrocarbon, glacial acetic acid and the like. However, it is desirable to use an excess of phenol as solvent to increase the yield of product and minimize side reactions. The amount of phenol used is cyclohexanone-4-carboxylic acid ester 1
2 to 10 parts by weight per part by weight are suitable.

The reaction temperature in the present invention is in the range of 30 ° C to 100 ° C,
It is preferably in the range of 40 ° C to 70 ° C. If the reaction temperature is high, by-products increase and the yield decreases, which is not preferable.

The thus produced 4,4-bis (4-hydroxyphenyl) -cyclohexanecarboxylic acid ester and the by-produced acid discharge the reaction mass into a solvent in which these compounds are difficult to dissolve, such as benzene. After cooling and crystallization, solid-liquid separation is performed and the product is subjected to a decomposition dehydrogenation reaction.

Further, the phenol used in excess can be recovered and reused by a method such as filtering out a salt which has been neutralized and crystallized, or distilling under reduced pressure.

In the cracking dehydrogenation reaction of the present invention, the cracking reaction and the dehydrogenation reaction can be carried out as separate steps, but it is efficient to carry out in one step.

A base biocatalyst is used in the decomposition reaction. Efficient base biocatalysts for decomposition include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, alkaline earth metal hydroxides and carbonates such as magnesium hydroxide and barium hydroxide. , Acetate, phenoxide, salts of weak organic acids, etc.

Among these catalysts, strong basic catalysts such as sodium hydroxide are preferable, and are usually used for 4,4-bis (4-hydroxyphenyl) -cyclohexanecarboxylic acid ester of formula (II) and the corresponding by-produced acid. 2-40% by weight, preferably 5
Used in the range of up to 20% by weight.

In the decomposition dehydrogenation step of the present invention, the ester group of the compound of formula (II) is easily hydrolyzed to a free carboxylic acid by using a basic catalyst in this way, and the desired product is obtained in high yield. can get. The dehydrogenation reaction is usually carried out in the presence of a dehydrogenation catalyst. The catalyst is not particularly limited as long as it is a known dehydrogenation catalyst. Cobalt
Cobalt catalyst such as carrier catalyst, Raney copper, reduced copper, copper-
Copper catalyst such as carrier catalyst, palladium black, palladium oxide, colloidal palladium, palladium-carbon, palladium-barium sulfate, palladium-magnesium oxide, palladium-calcium oxide, palladium catalyst such as palladium-alumina, platinum black, colloidal platinum, oxidation platinum,
Platinum catalysts such as platinum-support catalysts such as platinum sulfide and platinum-carbon, colloidal rhodium, rhodium-carbon, rhodium catalysts such as rhodium oxide, platinum group catalysts such as ruthenium catalyst, rhenium heptoxide, rhenium-carbon, etc. Examples thereof include catalysts, copper chromium oxide catalysts, molybdenum oxide catalysts, vanadium oxide catalysts, tungsten oxide catalysts, and silver catalysts.

Among these catalysts, platinum group catalysts such as palladium catalysts are preferable. The proportion of these dehydrogenation catalysts used is such that the metal atom of the dehydrogenation catalyst is based on 1 mol of the 4,4-bis (4-hydroxyphenyl) -cyclohexanecarboxylic acid ester represented by the general formula (II) and the acid. Usually 0.01 ~
0.2 gram atom, preferably in the range of 0.004 to 0.1 gram atom.

The method of the present invention can be carried out without a hydrogen acceptor, but can be carried out in a higher yield by coexisting with the hydrogen acceptor.

The hydrogen acceptor does not need to be particularly limited, but includes several types of compounds. For example, organic compounds containing ethylenic unsaturation such as ethylene and propylene, organic compounds containing acetylenic unsaturation such as acetylene and methylacetylene, organic compounds containing azo groups such as azobenzene, nitro or Examples thereof include carbonyl compounds and phenol compounds.

Of these, preferred hydrogen acceptors are organic compounds containing conjugated double bonds such as styrenes such as α-methylstyrene, nidrobenzene, maleic anhydride, methylacetylene, crotonic acid and phenol. Moreover, these hydrogen acceptors are not only highly active, but also their products after hydrogenation, such as cumene in the case of α-methylstyrene,
In the case of phenol, it is better to select it so that it is useful such as cyclohexano.

The reaction temperature is 100 to 400 ° C, preferably 180 to 300 ° C. When the reaction temperature is low, the reaction rate is low, and when it is high, side reactions may occur, which is not a good strategy.

The method of the present invention can be carried out in the gas phase, but since the melting points of the raw materials and products are high, a high temperature of 300 ° C. or higher is required in the case of the gas phase reaction, and in terms of yield, operability, energy saving, etc. It is preferably carried out in the liquid phase. At that time, it is preferable to carry out in the presence of a solvent, and specifically, in addition to water, ethers such as ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, diethylene glycol monomethyl ether, tetrahydrofuran, dioxane, dipropyl ether and diphenyl ether, ethanol,
Examples include alcohols such as isopropanol, ethylene glycol, diethylene glycol, triethylene glycol and propylene glycol, nitriles such as acetonitrile, propionitrile and benzonitrile, and aromatic hydrocarbons such as benzene, toluene, xylene, mesitylene, ethylbenzene and cumene. . Further, it is possible to use the hydrogen acceptor as a solvent.

4-hydroxybiphenyl-4 thus produced
For the carboxylic acid, the target product of high purity can be obtained in high yield by separating the catalyst from the mixture after the reaction and then taking it out by a method such as crystallization.

Hereinafter, the present invention will be specifically described with reference to examples.

[Example-1] 62.5 g (0.40 mol) of methyl cyclohexanone-4-carboxylate, 188.2 g (2.0 mol) of phenol and 20 ml of 36% hydrochloric acid were added to a 300 ml reaction flask, and the mixture was stirred at 40 to 45 ° C for 5 hours for reaction. Let After completion of the reaction, the mixture was discharged into 500 ml of benzene and stirred at 20 ° C for 1 hour. The crystals were separated by filtration and dried to obtain 103.7 g of white crystals. Liquid chromatographic purity was 82.2% methyl 4,4-bis (4-hydroxyphenyl) -cyclohexanecarboxylate, 4,4-bis (4-
Hydroxyphenyl) -cyclohexanecarboxylic acid 17.7
%Met.

Next, 20.0 g of this white crystal was mixed with 2.7 g of caustic soda, 21.9 g of α-methylstyrene, 100 g of water and 0.4 g of 5% Pd-carbon to obtain 3 parts.
The mixture was charged into a 00 ml autoclave made of stainless steel, the inside was replaced with asphyxiation gas, and then the mixture was reacted at 250 ° C. for 4 hours. After the completion of the reaction, upon cooling, some crystals were precipitated, so 30.0 g of a 20% aqueous sodium hydroxide solution was added to dissolve the crystals, and the catalyst was separated by filtration. Benzene 10 from the filtrate
After extracting and recovering α-methylstyrene and cumene with 0 ml, hydrochloric acid was added to acidify 4′-hydroxybiphenyl-4-carboxylic acid. Crystals are filtered off, washed with water, dried and mp
13.0 g of 4'-hydroxybiphenyl-4-carboxylic acid having a temperature of 297 ° C was obtained. The purity by liquid chromatography was 99%, and the total yield from methyl cyclohexanone-4-carboxylate was 78%.

[Example-2] 68.1 g of ethyl cyclohexanone-4-carboxylate instead of 62.5 g of methyl cyclohexanone-4-carboxylate
(0.40 mol) was used to carry out the condensation reaction and treatment in the same manner as in Example-1 to obtain 4,4-bis (4-hydroxyphenyl).
109.6 g of a mixture of ethyl 82.4% cyclohexanecarboxylate and 17.6% 4,4-bis (4-hydroxyphenyl) -cyclohexanecarboxylic acid were obtained. Then 20.0 g of this mixture
Cleavage, dehydrogenation and treatment were carried out in the same manner as in Example 1 to obtain 12.5 g of 99% pure 4'-hydroxybiphenyl-4-carboxylic acid. The token yield from ethyl cyclohexanone-4-carboxylate was 79%.

Claims (1)

[Claims] 1. A general formula (I) (In the formula, R represents a lower alkyl group.) A cyclohexanone-4-carboxylic acid ester represented by the following formula is reacted with phenol in the presence of an acid catalyst to give a compound of the general formula (I
I) (Wherein R is the same as R in formula (I)) and 4,4-bis (4-hydroxyphenyl) -cyclohexanecarboxylic acid ester and 4,4-bis (4-
A process for producing 4'-hydroxybiphenyl-4-carboxylic acid, which comprises obtaining a mixture of (hydroxyphenyl) -cyclohexanecarboxylic acid, and then subjecting this mixture to a decomposition / dehydrogenation reaction in the presence of a base.