JPH0692342B2 - Process for producing 4'-hydroxybiphenyl-4-carboxylic acid - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel method for producing 4′-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.

(Prior Art) 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-Phenylphenol was converted to 4-methoxyphenyl by the Friedel-Crafts reaction.
A method for synthesizing methoxy-4'-acetone biphenyl, followed by oxidation to 4-methoxy-4'-carboxybiphenyl, and treating with hydrobromic acid to obtain the desired product [Journal of American Chemical Society (Journal of American Chemical Society J.
A..S., 58 , 1738)].

(B) A method of reacting p-iodobenzoic acid methyl ester with p-iodoanisole to obtain 4-methoxy-4'-carboxybiphenyl, followed by the same treatment as in (a) to obtain the desired product [buritin. Of the Chemical Society of Japan (Bull.Chem.Soc.Japan. 30 , 5
08-13, 1957)].

(C) Method for obtaining target compound by diazotization and hydrolysis of 4'-aminobiphenyl-4-carboxylic acid (FP735,84
6) etc. are known.

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

[Means for solving problems]

The present inventors have conducted intensive studies to improve the above-mentioned drawbacks of the conventional method, and as a result, have found a novel manufacturing method and arrived at the present invention. That is, the present invention has the general formula (I) (In the formula, R represents a hydrogen atom or a lower alkyl group.)
The 4-hydroxybenzoic acid represented by the formula (II) is prepared by catalytic hydrogenation reaction in a secondary alcohol or tertiary alcohol solvent. (In the formula, R is the same as R in formula (I).) A reaction mixture containing cyclohexanone-4-carboxylic acid is obtained, which is reacted with phenol in the presence of an acid catalyst to give a compound represented by the general formula (III ) (In the formula, R is the same as R in the formula (I)) 4,4-
Bis (4-hydroxyphenyl) -cyclohexanecarboxylic acid was obtained, and then this mixture was decomposed and dehydrogenated in the presence of a base and a dehydrogenation catalyst to give 4'-hydroxybiphenyl-4-carboxylic acid from 4-hydroxybenzoic acid. Is a series of industrial manufacturing methods for obtaining

In the method of the present invention, a compound represented by the general formula (II), which is a precursor of 4'-hydroxybiphenyl-4-carboxylic acid as a target product,
I) 4,4-bis (4-hydroxyphenyl) -cyclohexanecarboxylic acid ester and 4,4-bis (4
-Hydroxyphenyl) -cyclohexanecarboxylic acid is a new compound and was previously filed.

Further, the reaction of reacting cyclohexanone-4-carboxylic acid with phenol and then decomposing / dehydrogenating it to synthesize 4'-hydroxybiphenyl-4-carboxylic acid is a completely novel reaction, and was previously filed.

Furthermore, the present inventors have found that 4- (4)
When hydroxybenzoic acids are subjected to catalytic hydrogenation reaction,
Cyclohexanol-4-carboxylic acids, which are perhydrides, are by-produced in a relatively large amount that cannot be ignored, but cyclohexanol-4-carboxylic acids can easily become lactone compounds by removing water or alcohol by heating. Found out.

In particular, when the compound of the general formula (I) used as a starting material is an ester, the corresponding compound of the formula (II) can be obtained in a high yield in a hydrogenation reaction, but for example, by-product cyclohexanol-4
Methyl carboxylate is readily de-methanoled by heating to 2-oxabicyclo [2,2,2] octane-3-one. The difference between the boiling point of this lactone and the boiling point of methyl cyclohexanone-4-carboxylate represented by formula (II) is small, and a very large theoretical plate number and reflux ratio are required to separate the two by distillation, The loss of the compound of formula (II) during the separation is not small.

Therefore, in the catalytic hydrogenation reaction of the compound of formula (I), it is necessary to suppress the by-production of cyclohexanol-4-carboxylic acids as much as possible. In the present invention, 2
By carrying out the catalytic hydrogenation reaction in a tertiary or tertiary alcohol solvent, by-products such as cyclohexanol-4-carboxylic acids are suppressed to a low level, and cyclohexanone-4-carboxylic acids can be rapidly obtained in a high yield. Moreover, since the condensation reaction of the obtained cyclohexanone-4-carboxylic acid and phenol can be carried out in a liquid phase at a relatively low temperature of 100 ° C. or lower, preferably 40 to 70 ° C., the by-product perhydrogenated cyclohexanol Even if -4-carboxylic acids are mixed, the reaction rate is not affected and the lactone is not converted.

Therefore, in the condensation reaction with the phenol of the present invention, the reaction mixture can be used as it is, and the compound of formula (III) obtained by the condensation reaction is produced as a solid precipitate. Further, the perhydrogenated cyclohexanol-4-carboxylic acid can be easily separated by solid-liquid separation.

The present invention was invented based on these findings,
The compound of formula (I) is subjected to catalytic hydrogenation reaction in a secondary or tertiary alcohol solvent, and subsequently reacted with phenol in a reaction mass containing a perhydride to decompose the obtained compound of formula (III) into dehydrogenation reaction. By doing so, the desired 4'-hydroxybiphenyl-4-carboxylic acid can be industrially obtained in a high yield in a series of steps.

The preferred embodiments of the present invention are as follows.

As the secondary alcohol or tertiary alcohol which can be used in the reaction in the present invention, a compound which is liquid at the reaction temperature to be carried out and which is not hydrogenated under the reaction conditions is selected.
For example, aliphatic secondary alcohols such as isopropyl alcohol, sec-butyl alcohol, sec-amyl alcohol, diethyl carbinol, methyl isobutyl carbinol, 3-heptanol, methyl amyl carbinol, t-butyl alcohol, t-amyl alcohol, 1
And tertiary alcohols such as methylcyclohexanol.

Among these solvents, the suppression effect and price of perhydrogen compounds,
Isopropyl alcohol is one of the most preferable solvents in consideration of separation and recovery after the reaction.

The amount used is usually 0.5 to 5 parts by weight, preferably 1 to 3 parts by weight, relative to 1 part by weight of the hydroxybenzoic acid represented by the general formula (I).

The compound of formula (I) which can be used in the present invention includes p-hydroxybenzoic acid and its ester, that is, p
-Methyl hydroxybenzoate, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, butyl p-hydroxybenzoate and the like can be mentioned.

Further, as a catalyst that can be used in the catalytic hydrogenation reaction,
It is not particularly limited as long as it is a known hydrogenation catalyst, for example, Raney nickel, reduced nickel, nickel silicon earth, alumina, pumice stone, silica gel, nickel carrier catalysts supported on various carriers such as acid clay, Raney cobalt, reduced cobalt, cobalt- Cobalt catalysts such as carrier catalysts, Raney copper, reduced copper, copper catalysts such as copper-carrier catalysts, palladium black, palladium oxide, colloidal palladium, palladium-carbon, palladium-barium sulfate, palladium-magnesium oxide, palladium-alumina, etc. Platinum catalyst, platinum catalyst such as platinum black, colloidal platinum, platinum oxide, platinum sulfide, platinum-carrier catalyst such as platinum-carbon, rhodium catalyst such as colloidal rhodium, rhodium-carbon and rhodium oxide, platinum group catalyst such as ruthenium catalyst , Rhenium oxide, rhenium-carbon Rhenium catalysts, copper chromium oxide catalyst ,, oxide, molybdenum catalyst, vanadium oxide catalyst, tungsten oxide catalyst, such as silver catalysts.

Among these catalysts, platinum group catalysts such as palladium catalysts,
Nickel catalysts are preferred. Most preferably, it is a palladium catalyst. Palladium-carbon is one of the most preferred catalysts. The amount used is usually 0.0001 to 0 as a palladium atom based on 1 mol of 4-hydroxybenzoic acid as a raw material.
It is in the range of 2 gram atoms, preferably 0.0003 to 0.01 gram atoms.

The pressure of hydrogen is usually 1 to 50 kg / cm ² , preferably ² to 30 kg.
The range is / cm ² . Higher pressure tends to increase by-products.

Also, the reaction temperature varies depending on the amount of catalyst and solvent type, but usually
It is in the range of 80 to 200 ° C.

The crude cyclohexanone-4-carboxylic acid thus obtained in the hydrogenation reaction step is subjected to the next step as the reaction mass obtained by distilling off the solvent, but even if reacted with phenol in the condensation step 4, 4-bis (4-hydroxyphenyl) -cyclohexanecarboxylic acid and its ester do not contain the above impurities.

In the reaction of the cyclohexanone-4-carboxylic acid of the compound of formula (II) with phenol, the reaction is carried out in the presence of an acidic catalyst to obtain the corresponding compound of formula (III) 4,4-bis (4-).
Hydroxyphenyl) cyclohexanecarboxylic acids are obtained. When the compound of the formula (III) is an ester, a part of it is hydrolyzed at this time by using an acid catalyst to give 4,4-bis (4
-Hydroxyphenyl) -cyclohexanecarboxylic acid.

Of course, when R is a hydrogen atom in the formula (II), only 4,4-bis (4-hydroxyphenyl) -cyclohexanecarboxylic acid is obtained.

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

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-butyl mercaptan, isobutyl mercaptan, t
Alkyl mercaptans such as -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 to these can also be used.

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

The reaction temperature in this condensation reaction is in the range of 30 ° C to 100 ° C, preferably 40 ° C to 70 ° C. If the reaction temperature is high, by-products will increase and the yield tends to decrease.

The precursor 4,4-bis (4-hydroxyphenyl) -cyclohexanecarboxylic acid thus produced is produced by cooling the reaction mass by discharging the reaction mass into a solvent in which these compounds such as benzene are difficult to dissolve. Then, solid-liquid separation is performed, and the product is subjected to a decomposition dehydrogenation reaction. The by-products in the hydrogenation reaction are separated into the liquid phase without reacting with phenol.
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.

When R of the formula (II) is an alkyl group, 4,4-bis (4-hydroxyphenyl) -cyclohexanecarboxylic acid, which is a by-product of hydrolysis, is obtained by reacting the compound of the formula (III) under normal conditions. It is about 10 to 30% by weight, and it can be subjected to the decomposition / dehydrogenation reaction as a mixture with the ester without separation. Of course, it does not matter if they are separated.

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

A basic catalyst is used in the decomposition reaction. Efficient basic catalysts 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. , Acetates, phenoxides, salts of weak organic acids.

Among these catalysts, strong basic catalysts such as sodium hydroxide are preferred, and usually 2 to 40 relative to 4,4-bis (4-hydroxyphenyl) -cyclohexanecarboxylic acid ester of formula (III) and the corresponding acid. The dehydrogenation reaction is carried out in the presence of a dehydrogenation catalyst.
The catalyst is not particularly limited as long as it is a known dehydrogenation catalyst,
For example, Raney nickel, reduced nickel, nickel-supported catalysts of various types of carriers such as silicon earth, alumina, pumice, silica gel, acid clay, Raney cobalt, reduced cobalt, cobalt catalysts such as cobalt-supported catalysts, Raney copper, Reduced copper, copper catalysts such as copper-supported catalysts,
Palladium black, palladium oxide, colloidal palladium,
Palladium catalysts such as palladium-carbon, palladium-barium sulfate, palladium-magnesium oxide, palladium-calcium oxide, palladium-alumina, platinum-carrier catalysts such as platinum black, colloidal platinum, platinum oxide, platinum sulfate, platinum-carbon, etc. Platinum catalyst, colloidal rhodium,
Rhodium catalyst such as rhodium-carbon and rhodium oxide, platinum group catalyst such as ruthenium catalyst, rhenium heptaoxide, rhenium catalyst such as rhenium-carbon, copper chromium oxide catalyst, molybdenum oxide catalyst, vanadium oxide catalyst, tungsten oxide catalyst , Silver catalysts, and the like.

Among these catalysts, platinum group catalysts such as palladium catalysts are preferable. The ratio of these dehydrogenation catalysts to be used is usually such that the metal atom of the dehydrogenation catalyst is 1 mol with respect to 1 mol of the 4,4-bis (4-hydroxyphenyl) -cyclohexanecarboxylic acid ester represented by the general formula (III). 0.001 ~
0.2 gram atom, preferably in the range of 0.004 to 0.1 gram atom.

The dehydrogenation reaction of the present invention can be carried out without a hydrogen acceptor, but by coexisting with a hydrogen acceptor, the target product can be obtained in a higher yield.

The hydrogen acceptor need not be particularly limited, but includes several types of compounds. For example, ethylene, an organic compound containing ethylenic unsaturation such as propylene, acetylene, an organic compound containing acetylenic unsaturation such as methylacetylene, an organic compound containing an azo group such as azobenzene, nitro or Carbonyl compound,
Or a phenol compound etc. are mentioned.

Among these, preferred hydrogen acceptors are organic compounds containing a conjugated double bond such as styrenes such as α-methylstyrene, nitrobenzene, maleic anhydride, methylacetylene, crotonic acid and the like. Not only are these hydrogen acceptors highly active, but they should be selected so that the product after hydrogenation is a useful material, such as cumene in the case of α-methylstyrene.

The reaction temperature of the decomposition dehydrogenation reaction is 100 to 400 ° C, preferably 18
It is carried out in the range of 0 to 300 ° C. When the reaction temperature is low, the reaction rate is low, and when it is high, side reactions tend to occur.

The decomposition dehydrogenation reaction can be carried out in the gas phase, but since the boiling points of the raw materials and products are high, 300 ° C for the gas phase reaction.
The above high temperature is required, and it is preferable to carry out in the liquid phase from the viewpoint of yield, operability, energy saving and the like. At that time, it is preferable to carry out in the presence of a solvent. Specifically, in addition to water, ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, diethylene glycol monomethyl ether, tetrahydrofuran, dioxane, dipropyl ether, ethers such as diphenyl ether, ethanol, isopropanol. Alcohols such as 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.

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

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

[Example-1] Methyl p-hydroxybenzoate 45.6 g (0.30 mol), 5
% Palladium-carbon 0.23 g, 2-propyl alcohol 100
ml into a 300 ml stainless steel autoclave, and after replacing the inside with nitrogen gas, the temperature was 180 ° C and the gauge pressure was 20 kg /
cm ^2, and allowed to absorb 0.6 moles of hydrogen at 170 hours. After cooling
After filtering the catalyst, the solvent was distilled off to obtain 47.0 g of a liquid. The yield of methyl cyclohexanone-4-carboxylate was 77.6% and the yield of methyl cyclohexanol-4-carboxylate was 15.0% as analyzed by gas chromatography.

Next, the total amount of this liquid was charged into a 300 ml reaction flask together with 110.0 g of phenol and 10 ml of 36% hydrochloric acid and reacted at 60 ° C. for 5 hours. After completion of the reaction, the reaction mass was discharged into 300 ml of benzene and stirred at room temperature for 3 hours. The crystallized crystals were filtered, washed and dried to obtain 65.0 g of white crystals. As a result of the analysis, it was confirmed that methyl cyclohexanol-4-carboxylate was not contained in the crystals at all and was transferred to the filtrate.

Next, the total amount of the white crystals was charged into a 500 ml stainless autoclave together with 8.2 g of caustic soda, 1.2 g of 5% palladium carbon, 66.0 g of α-methylstyrene, and 300 ml of water, and the inside was replaced with nitrogen gas, and then at 250 ° C. for 4 hours. It was made to react. After the completion of the reaction, upon cooling, some crystals were precipitated, so 100.0 g of a 20% aqueous sodium hydroxide solution was added to dissolve the crystals, and the catalyst was separated by filtration. Benzene 30 from the filtrate
After extracting and recovering α-methylstyrene and cumene with 0 ml, hydrochloric acid water was added to acidify 4′-hydroxybiphenyl-4-carboxylic acid.

The crystals were filtered, washed with water and dried to obtain 42.4 g of 4'-hydroxybiphenyl-4-carboxylic acid. The purity as determined by liquid chromatography was 91.2%, and the yield based on methyl p-hydroxybenzoate was 60.2%.

[Example-2] 41.4 g (0.30 mol) of p-hydroxybenzoic acid, 2.1 g of 5% palladium carbon and 100 ml of isopropyl alcohol were charged into a stainless steel autoclave, and after the inside was replaced with nitrogen gas, the temperature was 120 ° C. 0.60 mol of hydrogen was absorbed at a gauge pressure of 20 kg / cm ² .

After cooling, the catalyst was filtered off and the solvent was distilled off to obtain 42.8 g of white crystals. As a result of analysis by gas chromatography, the yield of cyclohexanone-4-carboxylic acid was 40.3%, and the yield of cyclohexanol-4-carboxylic acid was 20.4%.

Next, the total amount of the crystals was charged into a 300 ml reaction flask together with 140 g of phenol and 15 ml of 36% hydrochloric acid and reacted at 45 ° C. for 6 hours.

After completion of the reaction, the mixture was discharged into a mixed solution of 500 ml of toluene and 100 ml of water and stirred at 20 ° C. for 1 hour. The crystals were separated by filtration and dried to obtain 31.0 g of white crystals. The purity of 4,4-bis (4-hydroxyphenyl) cyclohexanecarboxylic acid was 95.0%, and the yield in terms of purity from cyclohexanone-4-carboxylic acid was 78%.

Next, the total amount of the white crystals was charged into a 500 ml stainless autoclave together with 1.18 g of 5% palladium carbon, 4.5 g of caustic soda and 150 g of phenol, the inside was replaced with nitrogen gas, and the reaction was carried out at 200 ° C. for 6 hours. After the reaction was completed, the crystals that had crystallized in the reaction mass were filtered, and then 10% aqueous sodium hydroxide solution was added.
The catalyst was dissolved in 0 ml and the insoluble catalyst was collected by filtration. Hydrochloric acid was added to the filtrate until the pH reached 1, and 4'-hydroxybiphenyl-4-carboxylic acid was acidified.

The crystals were filtered, washed with water and dried to obtain 18.6 g of white crystals of 4'-hydroxybiphenyl-4-carboxylic acid having a purity of 99.5%. The yield in terms of purity from 4,4-bis (4-hydroxyphenyl) cyclohexanecarboxylic acid was 92%.

Claims (1)

[Claims] 1. A general formula (I) (In the formula, R represents a hydrogen atom or a lower alkyl group.)
The 4-hydroxybenzoic acid represented by the formula (II) is prepared by catalytic hydrogenation reaction in a secondary alcohol or tertiary alcohol solvent. (In the formula, R is the same as R in the formula (I).) A reaction mixture containing a cyclohexisanone-4-carboxylic acid is obtained, which is subsequently reacted with phenol in the presence of an acid catalyst to give a compound represented by the general formula ( III) (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 was obtained, and then this mixture was decomposed and dehydrated in the presence of a base and a dehydrogenation catalyst. 1. A method for producing 4'-hydroxybiphenyl-4-carboxylic acid, which comprises reacting elementary reaction.