JPH1036332A - Purification method of cyclohexanone oxime hydrochloride - Google Patents

Abstract

(57) [Problem] To remove water contained in an oil of cyclohexanone oxime hydrochloride subjected to a Beckmann rearrangement reaction. An organic solvent having low compatibility with water and being compatible with cyclohexanone oxime hydrochloride is added to cyclohexanone oxime hydrochloride, and water contained therein is separated and removed by azeotropic distillation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for removing water from cyclohexanone oxime hydrochloride.

[0002]

2. Description of the Related Art For example, cyclohexanone oxime is industrially useful as an intermediate starting material for ε-caprolactam, which is a nylon starting material. .

[0003] However, the oily cyclohexanone oxime hydrochloride obtained by this method is usually about 1 to about 1%.
Contains water by weight. Therefore, when the oxime is converted into a lactam by Beckmann rearrangement, the Beckmann rearrangement catalyst is deactivated.

[0004] However, the oily cyclohexanone oxime hydrochloride obtained by this method is thermally unstable and cannot be removed by ordinary distillation, so that it is directly subjected to the Beckmann rearrangement reaction.

[0005]

Accordingly, there is a need for a method for separating and removing the water contained in the oily cyclohexanone oxime hydrochloride to be subjected to the Beckmann rearrangement reaction under the condition that the oxime is not decomposed.

[0006]

The object of the present invention is to provide an azeotropic distillation by adding an organic solvent having a low compatibility with water to oily cyclohexanone oxime hydrochloride and having compatibility with oily cyclohexanone oxime hydrochloride. By,
The problem is solved by separating and removing the contained water.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail.

Specific examples of the organic solvent used in the present invention which has low compatibility with water and is compatible with cyclohexanone oxime hydrochloride include halogenated hydrocarbons such as chloroform and 1,2-dichloroethane, benzene and chlorobenzene. And aromatic hydrocarbons, among which,
Chloroform and 1,2-dichloroethane are particularly preferred.

The amount of the organic solvent to be used is generally 0.1 to 20 times by weight, preferably 0.5 to 5 times by weight, based on the weight of the oil of cyclohexanone oxime hydrochloride. If the amount of the organic solvent is too small, the distillation temperature cannot be reduced to 90 ° C. or lower, and if it is too large, it is economically wasteful.

In the present invention, by using the above-mentioned organic solvent,
It is desirable from an economic viewpoint that the condensed distillation liquid is separated into two liquid layers of an organic solvent and water, and only the organic solvent layer is returned to the distillation section. Distillation may be a batch method, a continuous method, or a simple distillation, but it is preferable to supply a raw material from a middle column or an upper column of a packed column having 2 to 5 theoretical plates or a tray column and installing a column. .

[0011]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

Example 1 In a 500 ml distillation flask, cyclohexanone oxime hydrochloride oil (cyclohexanone oxime 63% by weight,
Hydrochloric acid 36% by weight, water 1% by weight, 100 g of hydrochloric acid to cyclohexanone oxime (molar ratio: 1.77) and 100 g of 1,2-dichloroethane were charged and evaporated under a pressure of 10.9 KPa. Of the organic solvent was refluxed to the distillation flask with a metering pump. At this time, the internal temperature of the distillation flask was 30 ° C. After treating for 1 hour at an evaporation rate of 500 g per hour, the amount of cyclohexanone oxime was analyzed by gas chromatography, the amount of hydrochloric acid was analyzed by silver nitrate titration, and the amount of water was analyzed by Karl Fischer titration. The water concentration was reduced to 0.026% by weight based on the weight of the charged oil, the decomposition rate of cyclohexanone oxime was 0.1% or less of the charged amount, and the molar ratio of hydrochloric acid to cyclohexanone oxime was 1.00.

Example 2 The procedure of Example 1 was repeated, except that chloroform was used as the organic solvent instead of 1,2-dichloroethane, and the organic solvent was evaporated under a pressure of 17.7 KPa. At this time, the internal temperature of the distillation flask was 30 ° C. As a result of analysis after the treatment, the water concentration was 0.178 based on the weight of the charged oil.
The decomposition rate of cyclohexanone oxime was 0.1% or less of the charged amount, and the molar ratio of hydrochloric acid to cyclohexanone oxime was 1.00.

Example 3 The procedure of Example 1 was repeated except that chloroform was used instead of 1,2-dichloroethane as the organic solvent, and the pressure was changed to atmospheric pressure instead of 17.7 KPa.
At this time, the internal temperature of the distillation flask was 70 ° C. As a result of analysis after the treatment, the water concentration was found to be 0.
The decomposition rate of cyclohexanone oxime was 0.1% of the charged amount, and the molar ratio of hydrochloric acid to cyclohexanone oxime was 1.01.

[0015]

According to the present invention, it is possible to remove the water contained in the oil of cyclohexanone oxime hydrochloride to be subjected to the Beckmann rearrangement reaction under conditions that hardly decompose the oxime. It can be greatly reduced.

Claims (5)

[Claims] 1. An organic solvent having low compatibility with water and being compatible with cyclohexanone oxime hydrochloride is added to cyclohexanone oxime hydrochloride, and water contained therein is separated and removed by azeotropic distillation. For purifying cyclohexanone oxime hydrochloride. 2. The method for purifying cyclohexanone oxime hydrochloride according to claim 1, wherein a halogenated hydrocarbon is used as an organic solvent having low compatibility with water and being compatible with cyclohexanone oxime hydrochloride. . 3. The cyclohexanone oxime hydrochloride according to claim 2, wherein chloroform or 1,2-dichloroethane is used as the organic solvent having low compatibility with water and being compatible with cyclohexanone oxime hydrochloride. Purification method. 4. The method for purifying cyclohexanone oxime hydrochloride according to claim 1, wherein the azeotropic distillation is performed at 90 ° C. or lower. 5. The method for purifying cyclohexanone oxime hydrochloride according to claim 1, wherein the cyclohexanone oxime hydrochloride is oily at room temperature.