A method for producing 2,6-dichlorobenzylidene dichloride while by-producing 2,6-dichlorotoluene

Abstract

The invention discloses a method for producing 2,6-dichloro benzal chloride with a byproduct of 2,6-dichlorotoluene. Through a chlorination-rectification-chlorination process, the method is capable ofmeeting a purpose of continuous reactions. The method comprises the following steps: by adopting a backpack type reaction rectification coupling mode and 2-chlorine-6-nitrotoluene as a raw material,adding the raw material and a catalyst into a chlorination reactor coupled with a rectification tower, and introducing chlorine to implement a chlorination reaction; transferring the material after the chlorination reaction into a #1 rectification tower, backflowing a top part of the tower, and discharging the material from the tower top to obtain 2,6-dichlorotoluene; transferring the residual material after the chlorination reaction into a #2 rectification tower, backflowing the top part of the tower, and discharging the material from the tower top to obtain 2-chloro-6-nitrotoluene, mixing the 2-chloro-6-nitrotoluene with a fresh raw material, circulating, transferring into the chlorination reactor, collecting residual liquid at the bottom of the #2 rectification tower as 2-chloro-6-nitrobenzyl chloride and 2,6-dichloro monobenzyl chloride, further mixing the product with the fresh raw material, feeding back to the chlorination reactor coupled with the rectification tower, and carrying out deep chlorination to obtaining 2,6-dichloro benzal chloride.

Description

technical field [0001] The invention relates to a method for producing chemical raw materials, more specifically to a method for producing 2,6-dichlorobenzylidene dichloride while by-producing 2,6-dichlorotoluene. Background technique [0002] 2,6-dichlorobenzylidene dichloride, also known as 2,6-dichlorobenzylidene dichloride, is used as an intermediate of 2,6-dichlorobenzaldehyde and 2,6-dichlorobenzonitrile in industrial production The deep chlorination reaction is carried out with 2,6-dichlorotoluene or 2-chloro-6-nitrotoluene as the raw material. The reaction mechanism is a free radical reaction. The chlorination temperature is high and the time is long. In addition to 2,6-dichlorobenzylidene dichloride, there are polychlorinated products such as 2,6-dichlorobenzyl chloride and 2,6-dichlorobenzylidene trichloride. Therefore, for green production, researchers Continuous research and improvement has been carried out. [0003] Chen Qun et al. (Chen Qun, chlorination proc...

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Problems solved by technology

[0004] The above-mentioned prior art uses 2-chloro-6-nitrotoluene as a raw material to synthesize 2,6-dichlorobenzylidene dichloride, and chlorination involves the substitution of nitro on the benzene ring, the one, two, and three chlorines of side chain methyl groups. Substitution and substitution of chloromethyl and other series-parallel reactions, so the process is more complicated, the reaction terminal is difficult to control, the deep chlorination, the yield is low, not only post-processing difficulties but also certain harm to the environment; with 2,6 -Dichlorotoluene is used as raw material for deep chlorination to obtain 2,6-dichlorobenzylidene dichloride, which also has these problems, and the cost is higher

When the reaction yield is not high, 2,6-dichlorobenzylidene dichloride contains a large amount of impurities which is not only unfavorable for subsequent reactions, but also causes serious environmental pollution

The Chinese patent whose publication number is CN 103172490A only relates to the rectification and separation of products, and does not relate to reactive distillation; and the Chinese patent whose publication number is CN 101070267A mentions a knapsack type reactive distillation device for producing benzylidene dichloride, but its The reaction raw materials and process are simple, and the generated components are single, so it is not suitable for complex chlorination reactions

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