Manufacturing technology of p-xylylene dichloride

Abstract

The invention provides a manufacturing technology of p-xylylene dichloride. The manufacturing technology comprises the following steps: (1) reaction: adding p-xylene in a chlorination reactor, turning on a reaction light source, and then turning on jacket steam of a reaction still to begin to heat and raise the temperature; when the temperature is raised to 80 DEG C, stopping steam heating, and introducing Cl2 to the reaction still; two hours after Cl2 introduction, increasing the chlorine flow, sampling to conduct center control analysis, and stopping introduction of the chlorine after meeting the process control requirements; (2) flash evaporation: simply distilling the mixed liquor obtained in the step (1), collecting the mixture of p-xylene and p-methylbenzyl chloride, and centrally collecting the bed charge inside the distillation still; (3) rectification: transferring the bed charge centrally collected in the step (2) to a benzylidene chloride rectifying column to be decompressed and rectified; collecting 4 mm Hg of fraction at 120-125 DEG C to obtain p-methylbenzylidene; collecting 4 mm Hg of fraction at 135-140 DEG C to obtain p-xylylene dichloride. The manufacturing technology disclosed by the invention can increase the yield of the product, achieves higher purity, and is easy for byproduct separation and purification.

Description

Technical field: [0001] The invention relates to the field of chemical industry, in particular to a process for producing p-dichlorobenzyl. Background technique: [0002] The traditional method for making p-dichlorobenzyl is to use glass reaction bottle to feed chlorine to obtain the p-methyl benzyl chloride crude product. In the crude product, p-xylene content is 60% (GC), and p-methyl benzyl chloride content is 30% (GC). The content of p-dichlorobenzyl is 3-5% (GC), the content of p-methylbenzylidene is 0.5-1.0% (GC), and the content of other impurities is 4% (GC). [0003] After flashing off p-xylene and p-methyl benzyl chloride, the residue of p-methyl benzyl chloride is obtained after rectification. Then, the finished product of p-dichlorobenzyl is obtained by cooling, crystallizing, centrifuging and drying with the offal of p-methyl benzyl chloride as raw material. However, in the process of obtaining the p-dichlorobenzyl finished product by the crystallization metho...

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Problems solved by technology

However, in the process of obtaining the p-dichlorobenzyl finished product by the crystallization method, due to the centrifugal drying method, a large amount of organized discharge gas permeates the operating environment during the operation, and is accompanied by dust, which has a great impact on the environment. Great impact, and caused great harm to the operator's body

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