Preparation method of p-chlorophenol

Abstract

The invention discloses a preparation method of p-chlorophenol. The preparation method comprises feeding chlorine gas into a mixture of phenol, copper chloride and a polar solvent under the normal pressure so that the mixture undergoes a full phenol chlorination reaction, and collecting p-chlorophenol from the chlorination reaction products, wherein the polar solvent is hydrochloric acid, dimethylsulfoxide or their mixed solvent. The preparation method utilizes a one-step reaction method, copper chloride as a chlorinating agent and the polar solvent, solves the problem that the existing copper chloride method needs harsh conditions such as high temperature and high pressure and the copper chloride conversion rate is low because of use of single copper chloride, and has high para-selectivity. After the reaction, the copper chloride-polar solvent can be used for the circular chlorination reaction.

Description

technical field [0001] The invention relates to a preparation method of p-chlorophenol. Background technique [0002] P-Chlorophenol is widely used in medicine, pesticide, dyestuff and other industries, and is an important organic chemical intermediate. Because the dye intermediate 1,4-dihydroxyanthraquinone has a large demand for the raw material p-chlorophenol, the domestic production of p-chlorophenol and the research on process optimization have become a hot spot. [0003] At present, there are three preparation methods of p-chlorophenol, chlorine gas method, sulfuryl chloride method and copper chloride method. In the direct chlorination method, phenol can be chlorinated directly with chlorine gas without a catalyst to generate p-chlorophenol, o-chlorophenol and a small amount of m-chlorophenol. The reaction conditions have a great influence on the selectivity of the target product p-chlorophenol. This method is simple in process and easy to operate, but its disadvanta...

AI Technical Summary

Problems solved by technology

This method is simple and easy to operate, but its disadvantage is that the para-selectivity is not high and a large number of by-products are generated

[0004] The sulfuryl chloride method uses sulfuryl chloride as the chlorination agent, and reacts to generate p-chlorophenol in the presence of a catalyst. The catalysts used mainly include iron trichloride, aluminum trichloride, etc., and the selectivity of the target product p-chlorophenol is very high , so this process route is a mature process commonly used in western industrialized countries, but the preparation process of the chlorinating agent sulfuryl chloride is complicated, the cost is high, it is uneconomical, and the reaction of ferric chloride is easy to pollute the environment as waste

[0005] The copper chloride method uses copper chloride as the chlorinating agent, and the selectivity of the target product of this route is relatively high. Japanese patent JPS5436221 uses copper chloride as the chlorinating agent, hydrochloric acid as the solvent, and reacts under high pressure at 130°C. The ratio reaches 10:1, but the disadvantage is that the reaction is carried out under high temperature and pressure; Acetic acid and N,N-dimethylformamide replace the water phase, copper chloride is used as the chlorinating agent, react in a pressure cooker at 180°C, and the ratio of monochlorinated products to / adjacent reaches 6:1. The disadvantage is that high temperature and high pressure are required, and The para-ortho ratio of monochlorinated products is low; Chlorine is passed into copper chloride-hydrochloric acid aqueous solution to prepare p-chlorophenol, extracted with dichloromethane after the reaction, and dichloromethane is evaporated after drying with anhydrous potassium carbonate, and the yield of p-chlorophenol is 65%. The yield of chlorophenol is low, the post-treatment is complicated, and the amount of raw material copper chloride is large, and the cost is high if it is not recycled.

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