JPS6013734A - Oxidation of phenol compound - Google Patents

Abstract

PURPOSE:To produce p-benzoquinone, by the liquid-phase oxidation of phenol or an alkylphenol free from the substituent group at the p-position of the OH group with O2-containing gas in the presence of active clay, silica gel or silica-alumina in the reaction liquid. CONSTITUTION:p-Benzophenone is produced by the liquid-phase oxidation of phenol or an alkylphenol compound free from substituent group at the p-position of the OH group with an oxygen-containing gas. The oxidation is carried out in a solvent such as acetonitrile, methanol, etc. in the presence of a copper catalyst and 0.2-2pts.wt. of powdery active clay, silica gel or silica-alumina based on 1pt.wt. of the phenolic compound. Benzoquinone can be produced in high yield when the reaction is carried out at about 10-20 deg.C and an oxygen partial pressure of about 10kg/cm<2>. USE:Antioxidant, an intermediate of hydroquinone derivative, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for the liquid phase oxidation of phenolic compounds to benzoquinone with an oxygen-containing gas.

Benzoquinone derivatives are themselves useful compounds as antioxidants, and the corresponding hydroquinone derivatives can be easily obtained by reduction.

Various attempts have been made to obtain benzoquinone derivatives from the corresponding alkylphenol compounds using various oxidizing agents, but few economical methods have yielded satisfactory results.

As a method for oxidizing a phenol compound with oxygen in the presence of a copper catalyst, for example, there is a method using a complex made from a copper catalyst and a solvent in a nitrile solvent as shown in JP-A-52-17432. However, the yield of quinone product increases with increasing oxygen partial pressure, and in the case of p~benzoquinone, pressures higher than about 100 atm are required to obtain a satisfactory yield. . Various improvement methods have been shown since then, but C-0 or C-C
Although the production of coupled polymers was unavoidable and the yields were low in both cases9, high oxygen pressure remains required. U.S. Patent No. 4,257,968 states:
A method for producing p-benzoquinone by oxidizing phenol with oxygen in a mixed solvent of acetonitrile and methanol in the presence of a copper catalyst has been disclosed, but this method cannot be applied to the oxidation of alkyl-substituted phenols. The selectivity and yield of alkyl-substituted quinones are still insufficient.

The present inventor has conducted research on the reaction of oxidizing an alkylphenol compound that is not substituted at the nocra position to a p-benzoquinone derivative, and first converted 〇-tertiary glycylphenol into a nitrile or a nitrile and a lower aliphatic alcohol or a lower fatty acid ester. invented a method for producing tertiary-glutyl-p-benzoquinone, which is characterized by oxygen oxidation in the presence of a cuprous chloride or cuprous bromide catalyst in a dilute solution in a mixed solvent of -69215), but in this invention, the phenol compound in the reaction solution is
Since it is necessary to maintain a dilute solution with a diameter of 0 φ or less, the productivity of the product is difficult, and it is necessary to devise ways to maintain the economic efficiency of industrial implementation. Furthermore, the selectivity was not sufficient for phenol and other alkylphenol compounds.

As a result of further research, the present inventor discovered that the above-described drawbacks of the conventional oxidation methods for alkylphenol compounds can be improved by adding activated clay, silica gel, or silica-alumina to the reaction solution. This invention has been achieved. That is, the present invention provides a method for liquid-phase oxidation of phenol or an alkylphenol compound having no substituent at the /4' position relative to the hydroxyl group to p-benzoquinone using an oxygen-containing gas, in which active clay, silica gel, or silica is used together with a copper catalyst. - It is an object of the present invention to provide a method for oxidizing a phenol compound, which is characterized in that the oxidation is carried out in the presence of alumina.The present invention will be explained in more detail below.

Phenol compounds that can be used in the present invention include phenol,
0 or m-cresol, 0 or m-tert-ditylphenol, 2.6-theta-diarynotylphenol, 0 or m-inglovirphenol, etc. or an alkylphenol compound having no substituent at the para position relative to the hydroxyl group・These phenol compounds are contained in the following solvent in an amount of 10 to 300, preferably 5 to 100.
It is used by dissolving it at a concentration of φ. If it is less than 10φ, productivity will be difficult, while if it is more than 300v1, the selectivity of the desired reaction product will decrease, making industrial implementation difficult.

Solvents that can be used in the present invention include acetonitrile, carbon number 4
The following alcohols or mixed solvents thereof, or mixed solvents of organic nitriles and acetic esters of alcohols having 4 or less carbon atoms are preferred, but polar solvents such as dimethyl sulfoxide and dimethyl formamide can also be used.

The activated clay, silica gel, or silica-alumina to be used together with the copper catalyst of the present invention is powdered and used in an amount of 0.2 to 2 parts by weight based on the phenol compound. If the amount of activated clay, silica gel, or silica-alumina is less than this range, the effect will be small, and if it is too much, there will be no particular problem in the reaction, but the effect will not be commensurate with that and it will be uneconomical.

As a copper catalyst, a monovalent copper halide such as cuprous chloride or cuprous bromide is usually used at a rate of 0.01% relative to the phenolic compound.
~0.51 part by weight is used. The form of the copper salt may be such that equimolar 7-rhodan ions are present in negative copper ions, and the treatment may be performed using equimolar amounts of cupric salt and metal steel.
It may also be one in which metallic copper and /41 o ) hydrogen fluoride are treated in equimolar amounts. In addition, if metallic copper, cupric chloride, cupric bromide, iron, ferrous chloride, ferric chloride, etc. are mixed and coexisted during this reaction, it is particularly bad for the selectivity of the target product. There is no effect.

Note that if the concentration of copper halide as a catalyst is within an appropriate range, it will have almost no effect on the selectivity of benzoquinone, but using a large amount of copper halide will be economically disadvantageous and may not be present in the reaction solution. It is not preferable because it becomes insoluble. On the other hand, in the method of the present invention, the reaction rate is usually 0.5 to 5011/11, (
is 5 to 2011/l (it is appropriate to use it in the D range).

Generally, the higher the reaction temperature, the lower the selectivity, but the reaction rate tends to increase. Therefore, the preferred temperature range is 0 to 100°C, and in particular, around 10 to 20°C is preferred in consideration of reaction rate and selectivity.

In addition to oxygen gas, an oxygen-containing gas such as air is also used as the oxygen source, but the higher the oxygen partial pressure during the reaction, the better the selectivity, and good results can be obtained from an oxygen partial pressure of 2 kgAtn2 or more. Regarding the upper limit of the oxygen partial pressure, there are no restrictions on the reaction, but if it is too high, there will be restrictions on the equipment, so up to 100 liters is appropriate6 10
Since benzoquinone can be obtained in high yield even with an oxygen partial pressure of around kg/crIt2, the reaction pressure around this point is
most preferred.

In general, it can be lower than when activated clay, silica glue, or silica-alumina is not used. Also,
Stirring efficiency also affects selectivity, so it is necessary to carry out effective stirring.

Next, the present invention will be specifically explained with reference to Examples.

Example 1 Phenol 10.01 was added to a 1/2 glass autoclave.
(0,106 mol) and acetonitrile 100-,
Methanol 1001d1 Cuprous chloride 2.0Ii, Powdered activated clay (Mizusawa Chemical Exhibition, Galleon Earth N) 10, Og
and maintained at 60℃, oxygen pressure 6.0 kg/crlG.
The mixture was reacted for 5.0 hours with vigorous stirring.

After the reaction was completed, the reaction solution was quantified by gas chromatography to determine the conversion rate of phenol, selectivity of p-benzoquinone,
The yield was estimated. The results are shown in Table 1.

Examples 2 to 7 Using the same method as in Example 1, the results shown in Table 1 were obtained for various alkylphenol compounds under the reaction conditions shown in Table 1.

Examples 8 to 13 Activated clay was mixed with powdered silica dal (Merck Silica Dull 6)
0, 70 to 230 meshes) were used for various phenols in the same manner as in Examples 1 to 12.
Nine results as listed in Table 2 were obtained under the reaction conditions listed in the table.

Example 14 In a 11 f glass autoclave, add 10.0.9 o-t-butylphenol and Zo acetonitrile.

d1 methanol 100 FILl, cuprous chloride 1. OII
, silica-alumina powder (catalyst chemical industry l5-13
) Add lO009, keep at 10℃, oxygen pressure 5.0kg
The reaction was carried out for 5.0 hours while stirring vigorously with #G. After the reaction was completed, the reaction solution was analyzed by gas chromatography, and the conversion rate of o-t-butylphenol was 98%.
The selectivity of t-butylbenzoquinone was 82% and the yield was 80%.

Comparative Example The results shown in Table 3 were obtained under the reaction conditions shown in Table 3 in the same manner as in the Examples except that activated clay, silica dal, or silica-alumina were not used.

As can be seen from the above Examples and Comparative Examples, according to the present invention, the selectivity of the target reaction product can be significantly improved even when productivity improvement measures such as keeping the concentration of the phenol compound high and the reaction temperature high are taken. can be kept high, thus p
- A method for oxidizing a phenol compound with high productivity and yield of benzoquinone can be achieved.

Patent applicant: Showa Denko Co., Ltd.

Claims (1)

[Claims] m In a method of liquid-phase oxidation of phenol or an alkylphenol compound that does not have a substituent at the position opposite to the hydroxyl group to p-benzoquinone using an oxygen-containing gas, oxidation is performed in the presence of activated clay, silica dal, or clicar alumina together with a copper catalyst. A method for oxidizing a phenolic compound, characterized by carrying out