JPH0759526B2 - Process for producing p-phenylphenols - Google Patents

Description

FIELD OF THE INVENTION The present invention relates to an improved process for the production of p-phenylphenols. More specifically in the presence of a hydrogen transfer catalyst,
The present invention relates to a method for producing p-phenylphenols, which comprises using phenols as hydrogen acceptors when decomposing and dehydrogenating 1,1-bis (4-hydroxyphenyl) cyclohexanes.

p-phenylphenols are raw materials for producing phenolic resins for special purposes such as varnishes, adhesives, and coating agents, pharmaceuticals,
It is used for manufacturing intermediates such as pesticides and antifungal agents.

2. Description of the Related Art Conventionally, many methods have been proposed as a method for producing p-phenylphenols.

For example, a method in which biphenyl is sulfonated to give p-phenylbenzenesulfonic acid, which is melt-decomposed in the presence of a base and then acid-deposited to obtain p-phenylphenols is a conventional typical production method. is there.

In recent years, many methods similar to the method of the present invention have been proposed.

That is, 1,1-bis (4-hydroxyphenyl) cyclohexane is decomposed into p-cyclohexenylphenol, and then dehydrogenation reaction is carried out in the presence of sulfur as a hydrogen acceptor (Japanese Patent Publication No. 44-3584). ), In which case α-methylstyrene or the like is used as a hydrogen acceptor, and the reaction is carried out in the presence of a dehydrogenation catalyst (JP-B-45-7046).

A method for producing p-phenylphenol by decomposing and dehydrogenating 1,1-bis (4-hydroxyphenyl) cyclohexane in the presence of a catalyst is also known (Japanese Patent Publication No. 47-18758). At that time, an improved method of decomposing and dehydrogenating in the presence of styrenes has already been proposed (JP-A-58-62127).

Problems to be Solved by the Invention However, in the above-mentioned conventional method, the method using biphenyl as a starting material requires a large amount of acid and base, and it is necessary to carry out the alkali melt decomposition reaction under severe conditions of 300 ° C. or higher. Therefore, it must be said that the industrial manufacturing method is a process including many problems in terms of equipment, wastewater treatment, and energy saving.

In addition, p-cyclohexenylphenol or 1,1-
In the method for producing p-phenylphenol from bis (4-hydroxyphenyl) cyclohexane by a dehydrogenation reaction, the yield is low when a dehydrogenation catalyst and a hydrogen acceptor are not used, and the amount of hydrogen generated in the system is low. It has a drawback that it is not used effectively.

The above-mentioned Japanese Patent Publication No. 45-7046 and JP-A No.
In the method disclosed in 58-62127, styrenes such as α-methylstyrene and the like are used as hydrogen acceptors.

However, since these hydrogen acceptors are converted into compounds that are originally unrelated to the production of p-phenylphenols after the reaction is completed, it is necessary to purify and separate them after the completion of the reaction, let alone reuse of these hydrogen acceptors. Yes, unless necessarily considering the effective utilization of hydrogen acceptor compounds such as styrenes,
Industrially, it has a drawback of being extremely expensive.

Means for Solving the Problems The inventors of the present invention have made diligent studies on a method of improving the above-mentioned drawbacks of the conventional method and selectively producing p-phenylphenols in a high yield. As a result, in the presence of a hydrogen transfer catalyst. , 1,1-bis (4-
The present inventors have found that the above object can be achieved by allowing phenols to coexist as a hydrogen acceptor when decomposing and dehydrogenating hydroxyphenyl) cyclohexanes, and reached the present invention.

That is, the present invention has the general formula [I] (In the formula, R ¹ represents a hydrogen atom, a hydroxyl group, or a lower alkyl group, and R ₂ represents a hydrogen atom or a lower alkyl group), 1,1-bis (4-hydroxyphenyl) cyclohexanes When the thermal decomposition dehydrogenation reaction is performed, phenols are used as hydrogen acceptors, the general formula [II] (In the formula, R ₁ and R ₂ are the same as the above.) A method for producing p-phenylphenols.

Since the method of the present invention uses phenols as hydrogen acceptors, it has the following advantages. That is, the phenols can be used not only as a hydrogen acceptor but also as a reaction solvent, and there is no need for purification and separation as in the case where a known solvent such as toluene is used. Further, the hydrogen generated during the production of p-phenylphenols is used for the reduction of the phenols to the corresponding cyclohexanones, so that not only is the hydrogen effectively utilized, but the produced cyclohexanones are This is an extremely simple and excellent method for producing p-phenylphenols, since it can be used as a synthetic raw material for 1,1-bis (4-hydroxyphenyl) cyclohexanes as a raw material.

The 1,1-bis (4-hydroxyphenyl) cyclohexanes that can be used in the method of the present invention are represented by the above general formula [1].
When R ₁ and R ₂ are lower alkyl groups, an alkyl group having 1 to 4 carbon atoms can be usually used, and specifically, a methyl group, an ethyl group, an n-propyl group, Isopropyl group, n-butyl group, sec-butyl group, t
Examples thereof include an ert-butyl group and an isobutyl group. In particular, R ₁
And R ₁ is a hydrogen atom or a methyl group, 1,1-bis (4
-Hydroxyphenyl) cyclohexanes are preferred.

Examples of the phenols used in the method of the present invention include phenol, methylphenol, ethylphenol, isopropylphenol, butylphenol and the like, with preference given to phenol and methylphenol. The amount used in the reaction system is in the range of 1.0 to 10 mol per mol of 1,1-bis (4-hydroxyphenyl) cyclohexanone. If it is less than 1.0 mol, the reaction rate is low, and if it is used in excess of 10 mol, the reaction rate is not affected, but it is not preferable in terms of volumetric efficiency and economical efficiency. Of course, a normal organic solvent inert to the reaction, for example, an aromatic hydrocarbon such as benzene, toluene and cumene may be used, but in that case, it is necessary to purify and separate after the reaction, which is complicated and economical. Instead, it is better to use phenols as the self-solvent.

The catalyst used in the method of the present invention needs to be a catalyst having both functions of dehydrogenation reaction and reduction reaction, but usually a suitable hydrogenation reduction reaction catalyst is also suitable for dehydrogenation reaction. Specifically, Raney-Nickel, reduced Nickel or Nickel-supported catalyst, Raney cobalt, reduced cobalt or cobalt-supported catalyst, Raney copper, reduced copper or copper-supported catalyst, precious metal catalyst of Group 8 of the periodic table or its precious metal as a carrier, Examples thereof include catalysts supported on carbon, alumina, barium carbonate, rhenium catalysts such as rhenium-carbon, and copper-chromium oxide catalysts. Of these catalysts, palladium is preferred, and palladium-
Palladium catalysts supported on carriers such as carbon, palladium-alumina, and palladium-magnesium oxide are preferred. The amount used is usually 1,2 bis (4-hydroxyphenyl) cyclohexane as a catalyst metal
0.001 to 1.0% by weight, preferably 0.005 to 0.5% by weight is good.

The reaction temperature is 200 to 300 ° C. If it is lower than this range, the reaction rate is low, and if it is higher, side reactions may occur, which is not a possible measure, and a temperature range of 230 to 280 ° C is preferably selected.

Reaction pressure is usually 1 to 40 kg / cm ² G, preferably ^{2 to 20} kg / cm
A range of ² G is good.

The p-phenylphenols produced in the method of the present invention can be obtained by treating the mixture after completion of the reaction according to a conventional method such as distillation, crystallization and extraction.

Next, the method of the present invention will be specifically described by way of Examples.

Example 1 80.4 g of 1,1-bis (4-hydroxyphenyl) cyclohexane was added to a stainless steel autoclave having an internal volume of 300 ml.
(0.3 mol), phenol 84.6 g (0.9 mol) and 5% pd /
1.61 g of carbon was charged and the inside of the autoclave was replaced with nitrogen. The temperature was raised to 250 ° C. and the reaction was carried out at the same temperature for 2 hours. After the reaction completion liquid was heated to separate the catalyst, the catalyst was washed with phenol. The liquid is distilled to obtain p-phenylphenol 5
I got 1.1g. The purity was 99.5% as determined by gas chromatography (yield 99.5%). At that time, as a result of quantification by gas chromatography, 26.4 g (0.27 mol) of cyclohexanone was contained in the recovered phenol.

Example-2 The amount of phenol in Example-1 was 28.2 g (0.3 mol).
Example 1 was repeated except that the above was changed to. 50.7 g of p-phenylphenol was obtained (purity 99.5%). Cyclohexanone was found to be 2
It contained 6.1 g (0.26 mol).

Example-3 The procedure of Example-1 was repeated, except that the amount of phenol was changed to 282 g (3 mol) in Example-1. 51.1 g of p-phenylphenol was obtained (purity 99.5%). The recovered phenol contained 26.8 g (0.27 mol) of cyclohexanone as determined by gas chromatography.

Claims (1)

[Claims] 1. A compound represented by the general formula [I] in the presence of a hydrogen transfer catalyst. (Wherein R ₁ represents a hydrogen atom, a hydroxyl group or a lower alkyl group, and R ₂ represents a hydrogen atom or a lower alkyl group), and heated 1,1-bis (4-hydroxyphenyl) cyclohexane 1,1 during the decomposition dehydrogenation reaction
-Bis (4-hydroxyphenyl) cyclohexanes 1
1.0 to 10 moles of phenols relative to moles are added as a hydrogen acceptor and reacted to react with the compound of the general formula [I
I] (In the formula, R ₁ and R ₂ are the same as above.) A method for producing p-phenylphenols.