CN1264697A

CN1264697A - Process for preparing monochloroacetic acid

Info

Publication number: CN1264697A
Application number: CN 00112627
Authority: CN
Inventors: 李守昌; 陈仁霖; 应佐奎
Original assignee: JIALING CHEMICAL PRODUCTS CO Ltd CHONGQING
Current assignee: Chongqing Changyuan Chemical Corporation Limited
Priority date: 2000-01-14
Filing date: 2000-01-14
Publication date: 2000-08-30
Anticipated expiration: 2020-01-14
Also published as: CN1105702C

Abstract

A process for preparing monochloroacetic acid includes proportioning acetic acid and sulfur, introducing chlorine gas at 90-100 deg.C, leading out the resultant acetyl chloride gas, condensing to become liquid, sucking it by cold acetic acid, mixing the liquids obtained previously, preheating, continous chlorinating reaction in tower while introducing chlorine gas to it, condensating the resultant chloroacetyl chloride and acetyl chloride gas for recovering them and cyclic generation of raw monochloroacetic acid. Its advantages are high reaction speed, continuous hydrogenation reaction, use of existing equipment and simple process.

Description

Process for preparing monochloroacetic acid

The present invention relates to a process for preparing monochloroacetic acid.

At present, solid sulfur (S) is used as a catalyst in the chlorination reaction for preparing monochloroacetic acid domestically, is used for chlorination reaction in an intermittent enamel reaction kettle, is not suitable for tower-type continuous chlorination reaction, has too low reaction speed and poor catalytic effect, and is used for preparing acetic anhydride [ (CH) for monochloroacetic acid by individual enterprises at home and abroad and in China₃CO)₂O]As a catalyst, the acetic anhydride is more than one time higher than acetic acid, and the dosage is large, thus being uneconomical. Acetic anhydride belongs to an intermediate of a drug, and has complex management and monitoring relation and inconvenient use.

The invention aims to provide a process for preparing monochloroacetic acid, which is particularly suitable for tower-type continuous chlorination operation, and has good catalytic effect and high reaction speed.

The above object of the present invention is achieved by a technical solution of a process for preparing monochloroacetic acid, characterized in that: the method comprises the following steps:

1. adding acetic acid and sulfur into an enamel reaction kettle according to the ratio of 25-35: 0.5-1.5, introducing chlorine gas at the temperature of 90-100 ℃, and keeping the reaction time as follows: generating gases such as acetyl chloride and the like within 7-9 hours;

2. leading out the gas in the reaction kettle, cooling the gas by a condenser to obtain liquid acetyl chloride, and then leading the liquid acetyl chloride and the residual gaseous acetyl chloride into another enamel kettle to be absorbed by cold acetic acid for later use;

3. preparing the liquid materials generated in the step 1 and the step 2 in a preparation kettle according to the proportion of 2: 1, and preheating at the temperature of about 60 ℃;

4. and (3) continuously placing the liquid material prepared in the step (3) into a chlorination reaction tower from the top at a high position, introducing chlorine gas into the bottom of the reaction tower, maintaining the temperature in the tower at 90-120 ℃, discharging the generated hydrogen chloride gas, recovering the chloroacetyl chloride gas after the chloroacetyl chloride gas is changed into liquid through a condenser, reacting with acetic acid in the tower to generate a chloroacetic acid crude product, leading out the chloroacetic acid crude product, reacting the generated acetylchloride gas with the chlorine gas, then regenerating the chloroacetyl chloride gas, condensing the chloroacetic chloride gas and then circulating the chloroacetic acid in the tower. The reaction formula is as follows:

the attached drawing is a block diagram of the process steps of the invention.

Referring to the drawings: a preferred embodiment of the present invention is: adding acetic acid and solid sulfur into an initial material reaction kettle according to the ratio of 30: 1, and then introducing chlorine for 8 hours; the temperature in the continuous chlorination reaction column was chosen to be 100 ℃.

The invention has the following advantages due to the process:

1. the catalytic effect is good, the chlorination reaction speed is high and is not lower than that of acetic anhydride;

2. liquid state mixing, no caking or hole blockage phenomenon, and suitability for tower type continuous chlorination reaction operation;

3. the preparation of the catalyst utilizes the existing production equipment and conditions;

4. the preparation is carried out on site in the production process, and the method is simple and convenient;

5. the condensation and recycling of gases such as acetyl chloride and the like in the process are cheaper than acetic anhydride and other catalysts, and the economical efficiency is good.

Claims

1. A process for preparing monochloroacetic acid is characterized in that: the method comprises the following steps:

(1) adding acetic acid and sulfur into an enamel reaction kettle according to the ratio of 25-35: 0.5-1.5, introducing chlorine gas at the temperature of 90-100 ℃, and keeping the reaction time as follows: generating gases such as acetyl chloride and the like within 7-9 hours;

(2) leading out the gas in the reaction kettle, cooling the gas by a condenser to obtain liquid acetyl chloride, and then leading the liquid acetyl chloride and the residual gaseous acetyl chloride into another enamel kettle to be absorbed by cold acetic acid for standby;

(3) preparing the liquid materials generated in the step 1 and the step 2 in a preparation kettle according to the proportion of 2: 1, and preheating at the temperature of about 60 ℃;

(4) continuously placing the liquid material prepared in the step 3 into a chlorination reaction tower from the top at a high position, introducing chlorine gas into the bottom of the reaction tower, maintaining the temperature in the tower at 90-120 ℃, discharging generated hydrogen chloride gas, recovering the chloroacetyl chloride gas after the chloroacetyl chloride gas is changed into liquid through a condenser, reacting with acetic acid in the tower to generate a monochloroacetic acid crude product, leading out, reacting the generated acetyl chloride gas with the chlorine gas, then regenerating chloroacetyl chloride gas, condensing the chloroacetyl chloride gas and then circulating in the tower to generate monochloroacetic acid.