Method for preparing p-xylylene dichloride through ultraviolet-induced catalysis

Abstract

The invention relates to a method for preparing p-xylylene dichloride by ultraviolet-induced catalysis, wherein the method comprises the following steps: step 1, adding p-xylene and a catalyst into areaction kettle, and slowly heating to a certain temperature; turning on an ultraviolet lamp, introducing chlorine gas from the bottom (or inserting a gas guide pipe into the bottom), and controllingthe introduction rate of the chlorine gas until a tail gas absorption liquid is slightly bubbled; when the temperature rises to 100 DEG C, heating is stopped, carrying out heat preservation, and introducing chlorine gas at the constant temperature for reaction; and after 5 hours, monitoring the reaction process by gas chromatography to obtain a high-temperature reaction solution; step 2, pre-adding a large amount of water into another kettle with strong stirring, and rapidly adding the reaction solution obtained in the step 1 into the water under strong stirring to form a large amount of whiteprecipitates; step 3, carrying out suction filtration, and rinsing the obtained white solid with water several times. and step 4, drying to obtain the target product p-xylylene dichloride.

Description

technical field [0001] The invention relates to the field of organic chemical synthesis, in particular to a method for synthesizing p-dichlorobenzyl. Background technique [0002] p-Dichlorobenzyl is an important chemical raw material, its appearance is white crystal or powder, and its melting point is 98-102 degrees Celsius. It can be used to produce terephthalamide; terephthalaldehyde; p-xylylene dimethyl ether and other downstream chemical raw materials; using p-dichlorobenzyl as a crosslinking agent can synthesize polysulfone hollow fiber nanofiltration composite membrane; it is also a Important pharmaceutical intermediates; in addition, it is also widely used in the synthesis of dyes and sewage treatment agents. [0003] There are many ways to also synthesize p-dichlorobenzyl, for example, using p-phenylenedimethanol as a raw material, using NMP as a solvent, chlorinating through benzoyl chloride (CN 106187674); or using dichloromethane as a solvent, using thionyl chlo...

AI Technical Summary

Problems solved by technology

The above methods either use other solvents, or use p-xylene as a solvent, and are also chlorinated in the form of raw materials, which have problems such as low conversion rate and high cost; The crude product with low content can be obtained, and the final product must be rectified under high temperature and vacuum. The whole process is long and requires high equipment, so the pressure on environmental protection and cost are relatively high.