JPH02311433A - Production of dihydric phenol - Google Patents

Abstract

PURPOSE:To easily obtain the subject compound in high yield without necessitating any additional treatment by carrying out a nuclear hydroxylation with phenol using a ketone peroxide or a combination of a ketone and hydrogen peroxide in the presence of a dithiolanethione as the catalyst. CONSTITUTION:Using a dithiolanethione (esp. pref. 1,3-ditholane-2-thione) as catalyst, a phenol is put to nuclear hydroxylation by reaction with a ketone peroxide or a combination of a ketone and hydrogen peroxide to obtain the objective dihydric phenol. The dithiolanethione as the catalyst is pref. a compound of formula I or II (R1 to R4 are each H, alkyl or aryl, at least two of them may form a ring). With the present process, high yield can be accomplished, additional treatments such as neutralization are not required, and also isolation can easily be made. The present process is simple; therefore, catechol, hydroquinone, etc., useful as raw material for medicines, pesticides, perfumes, etc., can be produced in high purity at low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Application Field" The present invention relates to a method for producing dihydric phenols such as catechol and hydroquinone, which are useful as raw materials for medicines, agricultural chemicals, fragrances, and the like.

``Conventional technology'' Conventionally, phenols have been converted to nuclear oxygen to produce catechol,
One of the methods for obtaining hydroquinone, etc., which provides the highest yield, is the ketone peroxide method, in which phenol and ketone peroxide are reacted in the presence of a catalyst (Japanese Patent Publication No. 52-38546, Japanese Patent Publication No. 52-38547). Publication No.). According to this method, when using a sulfuric acid catalyst under the condition of a molar ratio of phenol/hydrogen peroxide of -20/1,
゜1%, up to 97% when using various sulfate catalysts.
Dihydric phenol is obtained with a yield of 1%.

"Problem to be Solved by the Invention" However, no matter which production method has been proposed so far, satisfactory results have not been achieved in terms of yield and isolation of the product after the reaction. Haven't gotten it yet. For example, in the above-mentioned ketone peroxide method, when various sulfate catalysts are used, the amount of catalyst used is extremely large, making it difficult to separate the product from the product, and a neutralization step may also be required. However, it cannot be said to be industrially advantageous. Furthermore, when sulfuric acid is used as a catalyst, only a small amount is required, but a neutralization step is still required and the yield is considerably reduced.

The present invention was made in view of the above circumstances, and aims to provide a method for producing dihydric phenols such as catechol and hydroquinone, which has a high yield and is easy to process after the reaction. .

"Means for Solving the Problems" The present inventors have discovered that the above objects can be achieved by reacting phenols with ketone peroxide or ketone and hydrogen peroxide in the presence of dithiolanthiones. This discovery led to the completion of the present invention.

Hereinafter, the method for producing dihydric phenols of the present invention will be explained in detail.

As mentioned above, in the method for producing dihydric phenols of the present invention, when phenols are nuclear oxidized by reacting with ketone peroxide or ketone and hydrogen peroxide, this reaction is carried out in the presence of dithiolanthione. It is characterized by carrying out nuclear oxidation.

Examples of the phenols include phenol, alkylphenol, halogenated phenol, etherified phenol, etc. Among them, phenol, p-(tert-butyl)phenol, p-cresol, anisole, etc. are preferable, and among them, phenol is particularly preferable.

Further, in the present invention, as the oxidizing agent used for nuclear oxidation of phenols, (1) ketone and hydrogen peroxide, and (2) ketone peroxide are used.

In the above (2), the ketone used together with hydrogen peroxide is not particularly limited, but may be of the general formula (wherein R6 and R represent an alkyl group or an aryl group having 1 to 12 carbon atoms. and R1 may form a ring.) Compounds represented by these are preferred.

Examples of the ketone represented by the above-mentioned formula (I) include:
Examples include methyl isobutyl ketone, methyl ethyl ketone, acetone, cyclohexanone, and acetophenone.

Further, the concentration of hydrogen peroxide used together with the ketone is not particularly limited, but it is preferably as high as possible, particularly preferably 60% by weight or more.

The amount of the above ketone used is 0 per mol of hydrogen peroxide.
, 01 to 10 mol is suitable.

It is also possible to use a large amount of ketone as a solvent.

Examples of methods for using this ketone and hydrogen peroxide as oxidizing agents include a method in which the ketone and hydrogen peroxide are mixed in advance and then added to a mixed solution of phenols and a catalyst;
Examples include a method of adding hydrogen peroxide to a mixed solution of phenols, ketones, and catalysts, and any method may be used.

Examples of the above ketone peroxide include methyl isobutyl ketone peroxide, diisobutyl ketone peroxide, acetophenone peroxide, etc.
Among these, methyl isobutyl ketone peroxide is preferred in the present invention.

In the present invention, the amount of hydrogen peroxide or ketone peroxide used for phenols is 0.01 to 1.0 to 1 mole of phenols. It is preferably within the range of 0 mol.

If the amount used is more than 1.0 mol, it is not preferable because problems such as side reactions may occur.

A feature of the method for producing dihydric phenols of the present invention is that dithiolanthions are used as catalysts for the nuclear oxidation reaction of phenols. The dithiolanthions will be explained below.

In the present invention, among these dithiolanthions, the general formula (wherein Rl+Rt+R3,R represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group, and at least two of these may form a ring.) Dithiolanthions represented by the following are preferred, and specifically, 1, where R, , R, , R, , R, are both hydrogen atoms,
3-dithiolane-2-thione, or 1°2-dithiolane-3-thione, R, , R, , R3+ R.

Examples include dithiolanthions in which one or more of these is substituted with an alkyl group or an aryl group such as methyl, ethyl, n-propyl, 18o-propyl, n-butyl, etc.

In the present invention, in the above general formula, (I
) 1,3-dithiolane-2-thiones represented by the formula (1) are preferable, and among the 1,3-dithiolane-2-thiones represented by the formula (1), RI, Rt, Rs, R4 1,3-dithiolane-2-thione, in which both are hydrogen atoms, is particularly preferred.

The amount of catalyst used in the present invention can vary over a wide range, but in order to obtain a sufficient reaction rate, it is usually 0.0001 to 100 parts by weight per 100 parts by weight of the above phenols.
It is used in an amount of 1 part by weight, preferably 0.001 to 0.01 part by weight.

The reaction temperature of the nuclear oxidation reaction of phenols in the method for producing dihydric phenols of the present invention is preferably within the range of 50 to 200°C, and in order to obtain a sufficient reaction rate,
A range of 0 to 120°C is particularly preferred. Furthermore, the reaction temperature can also be adjusted by increasing or decreasing the amount of catalyst used.

After the nuclear oxidation reaction is completed, the target product can be isolated by a commonly used method.

That is, after water, ketones, and phenols are recovered by distillation, the target divalent phenols such as catechol and hydroquinone can be obtained by subsequent distillation or by methods such as recrystallization.

Note that the recovered ketones and phenols can be reused in the next reaction.

"Example" Hereinafter, the method for producing dihydric phenols of the present invention will be specifically described using Examples.

(Examples 1 to 6) A 300 mQ four-loaf flask was equipped with a stirrer, a condenser, and a thermometer, and 65.8 g (0.7 mol) of phenol and 3.5 g (0°043
5 mol), and 1,3-dithiolane-2 shown in Table 1
-3.3 mg of thiones were added.

The above mixture was heated to 100°C, 2.0 g (0,035 mol) of 60% by weight hydrogen peroxide solution was added, and the mixture was stirred for 1 hour. This reaction solution was analyzed by gas chromatography to determine the yields of catechol and hydroquinone. The results are shown in Table 1. In addition, ph in Table 1 represents a phenyl group.

(Example 7) Methyl isobutyl ketone peroxide 4.1 g (0,
Methyl isobutyl ketone solution containing 8.5 mol)
The experiment was conducted in the same manner as in Example 1 except that g was used. The results are shown in Table 1.

(Examples 8 to 12) Experiments were conducted using the same materials as in Example 1, the same blending amounts, and the same operations, except that the compounds shown in Table 2 were used as ketones. The results are shown in Table 2.

(Examples 13 to 15) Other than using the compounds shown in Table 3 as phenols,
An experiment was conducted in the same manner as in Example 1. The results are shown in Table 3.

(Comparative Examples 1 to 3) Experiments were conducted in the same manner as in Example 3, except that the types and amounts of catalysts were changed as shown in Table 4. The results are shown in Table 4.

(Hereinafter, in the margin) "Effects of the Invention" The present invention provides a method for producing dihydric phenols, which is characterized by reacting phenols with ketone peroxide, or ketones and hydrogen peroxide in the presence of dithiolanthione. Therefore, it is a production method that provides a good yield of dihydric phenols, does not require post-treatments such as neutralization, and is easy to perform post-reaction treatments such as isolation. Therefore, the method for producing dihydric phenols of the present invention has simple steps, and furthermore, it is suitable for pharmaceuticals, agricultural chemicals,
This method has the effect that dihydric phenols such as catechol and hydroquinone, which are useful as raw materials for perfumes, can be produced with high purity and at low cost.

Claims (3)

[Claims] (1) Phenols in the presence of dithiolanthione,
A method for producing dihydric phenols, which comprises reacting with ketone peroxide, or a ketone and hydrogen peroxide. (2) Dithiolanthions have the general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (I) or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (II) (In the formula, R_1, R_2, R_3, R_4 are , a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group, at least two of which may form a ring. 1. The method for producing dihydric phenols according to 1. (3) The method for producing dihydric phenols according to claim 1, wherein the dithiolanthione is a 1,3-dithiolane-2-thione represented by the general formula (I).