JPH08134001A - Production of aromatic glycol - Google Patents

Abstract

PURPOSE: To produce the subject compound with a common reaction apparatus under mild conditions in high yield by dissolving a dihalomethyl compound of an aromatic hydrocarbon in a mixed solvent of water with a water-soluble organic solvent and hydrolyzing the solution in the presence of a silver salt compound. CONSTITUTION: A dihalomethyl compound of a monocyclic, bicyclic or polycyclic aromatic hydrocarbon is dissolved in a mixed solvent of water with an water-soluble organic solvent. Subsequently, the solution is subjected to hydrolysis in the presence of a silver salt compound such as silver nitrate. This method enables the production of an aromatic glycol in high yield of 99% even at normal temperature and under atmospheric pressure. The compound used as raw material is preferably e.g. a dihalomethyl derivative of benzene, toluene, ethylbenzene, naphthalene, anthracene, biphenyl, etc. The water-soluble organic solvent is preferably acetone, tetrahydrofuran, methyl formate, etc. The method enables the production of the objective compound with a simple apparatus in high yield without accompanying by-products. Further, the production cost can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing aromatic glycols as raw materials for polymer materials, carbon fiber precursors and the like.

[0002]

2. Description of the Related Art Although various attempts have been made to produce a corresponding aromatic glycol using an aromatic dihalomethyl compound as a raw material, a high-purity aromatic glycol can be produced with a simple apparatus. No good industrial method is known.

As a method for producing aromatic glycols which has been widely used in the past, in an aqueous solution of a strong base such as sodium hydroxide or potassium hydroxide, or in an aqueous solution of a metal salt of a weak acid such as sodium carbonate or calcium carbonate. ,
There is a method in which aromatic dihalomethyl is heated, reacted with stirring at the reflux temperature of water, and oxidized to aromatic glycol.
However, since the reaction in this method is a heterogeneous reaction, it usually takes several hours or more to complete the reaction,
Sometimes it takes a few days. Further, an aromatic dihalomethyl compound usually produces a resinous substance, which is difficult to separate from the target product, as a by-product when treated for a long time in the presence of a strong base. It will be difficult.

As an improved method for solving the above-mentioned drawbacks, an aromatic dihalomethyl compound is allowed to act on an aromatic dihalomethyl compound in glacial acetic acid, and an alkali metal salt or an alkaline earth metal salt of acetic acid is reacted.
A method is known in which a corresponding diacetoxymethyl compound is obtained and then saponified in the presence of a strong base such as sodium hydroxide or potassium hydroxide to obtain an aromatic glycol. However, this method is based on a two-step reaction, requires the use of essentially unnecessary reagents, the first-step acetylation still takes several hours, and the second-step saponification The yield in the process is generally low.

Aromatic dihalomethyl compounds generally have sublimability, and, for example, α, α'-halogen-substituted xylenes are sublimed violently when heated under normal pressure for a long period of time, which significantly hinders the reaction.

Therefore, in order to increase the reaction temperature to promote the reaction and to avoid the reaction trouble due to sublimation of the starting aromatic dihalomethyl compound, a method using a pressurized system has been proposed. U.S. Pat. No. 2,938,886 discloses a method of reacting p-xylene dichloride with potassium acetate in water, wherein a closed system is used to prevent sublimation of p-xylene dichloride and to promote the reaction at 135 ° C. under pressure.
Discloses a method of carrying out the reaction. However, in this method, the yield of p-xylene glycol was 84.1% by weight even when the reaction was carried out for 11 hours, and the reaction was further carried out at 30 ° C. for 1 hour with the addition of sodium hydroxide.
Nothing more than.

Japanese Patent Publication No. 40-18296 discloses screws.
Disclosed is a technique in which chloromethyl-m-xylene is saponified continuously in the presence of calcium hydroxide at a high temperature of 120 ° C. or higher under pressure. According to this method, although the reaction time is significantly shortened as compared with the conventional method,
In addition, the retention time of 30 minutes is required, and the yield is limited to 87% by weight, so that the side reaction is not sufficiently suppressed.

JP-B-49-30820 discloses an oil which is obtained by heating a monocyclic or polycyclic aromatic hydrocarbon dihalomethyl compound to a temperature above its melting point or dissolving it in a water-soluble organic solvent. The aromatic hydrocarbon dihalomethyl compound is emulsified and dispersed in an aqueous solution of a hydroxide or carbonate of an alkali metal or an alkaline earth metal under strong shearing stirring or ultrasonic vibration without using an emulsifier. The saponification reaction was performed at a temperature of 100 ° C. or lower, and the result was a yield of 98.7%.
According to this method, the reaction time is significantly shortened and the yield is improved, as compared with the prior art. However, in this method, it is necessary to equip the reactor with a powerful high-speed agitator having a performance of 2000 rpm or more or an ultrasonic generator having a performance of 15 to 30 kilocycles / second, and at 100 ° C. A closed reactor is required to prevent sublimation of the aromatic dihalomethyl below. These devices are generally expensive, and it is very difficult to increase the size.

[0009]

Therefore, the present invention can be carried out under mild reaction conditions using a general reaction apparatus, can suppress side reactions and can be mass-produced. The main object of the invention is to provide a method for producing a class of products.

[0010]

Means for Solving the Problems As a result of intensive studies conducted by the present inventors in view of the above-mentioned state of the art, the dihalomethyl compound of aromatic hydrocarbon was converted into a mixture of water and a water-soluble organic solvent. It has been found that when dissolved and then hydrolyzed in the presence of a silver salt compound, an aromatic glycol can be obtained in a high yield of 99% or more even at room temperature and atmospheric pressure.

That is, the present invention provides the following method for producing an aromatic glycol; Aromatic glycol characterized in that a dihalomethyl compound of a monocyclic, polycyclic or polycyclic aromatic hydrocarbon is dissolved in a mixture of water and a water-soluble organic solvent and then hydrolyzed in the presence of a silver salt compound. Manufacturing method.

In the present invention, the compounds used as raw materials are benzene, toluene, ethylbenzene, o-, and m.
-And p-xylene, mesitylene, pseudocumene,
Dihalomethyl derivatives of monocyclic aromatic hydrocarbons such as durene and isodurene; Dihalomethyl derivatives of polycyclic aromatic compounds such as naphthalene, α- and β-methylnaphthalene and anthracene; Polycyclic compounds such as biphenyl and 3,3′-dimethylbiphenyl It is a dihalomethyl derivative of an aromatic hydrocarbon.

The silver salt compound used in the reaction is a combination of at least one silver salt compound such as silver nitrate, or a combination of these silver salt compounds with one of auxiliary components such as hydrogen peroxide and bis (tributyltin) oxide. use. By using a silver salt compound, the substitution reaction with glycols proceeds efficiently even when the pH of the solvent is under neutral conditions, and elimination and hydrolysis of the ester, which are problems during hydrolysis under basic conditions, occur. Side reactions such as decomposition can be suppressed.
The addition amount of the silver compound needs to be a chemical equivalent amount required for the substitution reaction. The silver halide compound formed after the reaction can be reused by the oxidation and nitrification reaction.

As the water-soluble organic solvent used by mixing with water, ketones such as acetone and methyl ethyl ketone; tetrahydrofuran, tetrahydropyran, 1,4
Ethers such as dioxane and ethylene glycol diethyl ether; soluble in water or relatively well soluble in water such as esters such as methyl formate, ethyl formate, methyl acetate, ethyl acetate and ethyl lactate, and raw materials Solvents that do not react with the aromatic dihalomethyl compounds of These water-soluble organic solvents may be used alone or in combination of two or more. These organic solvents are selected according to the structure of the aromatic dihalomethyl compound that undergoes the substitution reaction. Solvents having active hydrogen such as alcohols and amines are not suitable because they react with the raw material aromatic dihalomethyl compound even if they are soluble in water.

In the reaction, the aromatic dihalomethyl compound is dissolved in a mixture of water and an organic solvent, and the reaction is carried out in the presence of the silver salt compound, preferably at room temperature or a temperature in the vicinity thereof. If the reaction temperature is lower than the azeotropic point of the mixture of water and the organic solvent, it is possible to carry out the reaction at a higher temperature, but since the aromatic dihalomethyl compound as a raw material sublimes, the yield decreases. The reaction is preferably performed while stirring the reaction solution. Since the reaction is carried out under normal pressure and neutral conditions,
It can be performed using a container made of a general material such as glass or stainless steel. The reaction may be carried out in either an atmosphere of air or an inert gas, and may be carried out in a static atmosphere or in an air stream. The reaction time is
Although it may vary depending on the type of raw material, amount of raw material, reaction conditions, etc., it is usually about 2 hours.

[0016]

EFFECTS OF THE INVENTION According to the method of the present invention, aromatic glycols can be produced in a high yield without using side reaction products and by using a simple apparatus.

Further, in the method of the present invention, since the reaction conditions are mild, the reaction can be carried out under normal equipment specifications, so that the production cost can be reduced and it is suitable for industrial production. ing.

[0018]

EXAMPLES Examples and comparative examples will be shown below to further clarify the features of the present invention.

Example 1 10 g of 1,4-dimethyl-2,6-dichlorobenzene and 25 g of silver nitrate were added to 400 m of a 50% by volume aqueous acetone solution.
It was dissolved in 1 and reacted in the atmosphere for 2 hours while rotating the stirring blade in the cylindrical container.

After completion of the reaction, the reaction solution was filtered off, the filtrate was extracted 3 times with 200 ml of ether, and the extract was extracted with 100 ml of water.
After being washed twice with water and dried over anhydrous sodium sulfate, the ether was distilled off to obtain 8.1 g of dimethylparaxylene glycol. The yield was 99.0%.

Comparative Example 1 A reaction solution was prepared in the same manner as in Example 1 except that 10 g of 1,4-dimethyl-2,6-dichlorobenzene and 25 g of silver nitrate were dissolved in 400 ml of water and used for the reaction. Was filtered off, the filtrate was extracted, the extract was washed and dried to obtain 1.2 g of dimethylparaxylene glycol. The yield was 14.7%.

Comparative Example 2 2.5 g of 1,4-dimethyl-2,6-dichlorobenzene
And 4 g of sodium acetate are dissolved in 200 ml of a 50% by volume aqueous acetone solution, and the mixture is reacted in the air at 80 ° C. for 2 hours while rotating a stirring blade in a cylindrical container, and then cooled to obtain 2 g of sodium hydroxide. Was added. Then, the reaction solution was heated to 80 ° C. and reacted for 2 hours under the same conditions.

After completion of the reaction, the reaction solution was filtered off, the filtrate was extracted 3 times with 100 ml of ether, and the extract was extracted with 100 ml of water.
After being washed twice with, and dried over anhydrous sodium sulfate, the ether was distilled off to obtain 1.46 g of dimethylparaxylene glycol. The yield was 71.6%.

Front page continued (72) Inventor Takataka Kazaka 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi, Osaka Prefecture Osaka Gas Co., Ltd. (72) Hiroyuki Fujimoto 4--1, Hirano-cho, Chuo-ku, Osaka-shi, Osaka No. 2 within Osaka Gas Co., Ltd.

Claims (1)

[Claims] 1. A dihalomethyl compound of a monocyclic, polycyclic or polycyclic aromatic hydrocarbon is dissolved in a mixture of water and a water-soluble organic solvent and then hydrolyzed in the presence of a silver salt compound. And a method for producing an aromatic glycol.