Thr Study On Production And Purification Technology Of M-dichlorobenzene

M-dichlorobenzene is an indispensable fine chemical raw material in the chemical industry.It is mainly used in the production of pharmaceuticals,pesticides,dyes and pigments.With the rapid development of my country’s chemical industry in recent years,especially the introduction of new Chinese medicines in the pharmaceutical field,As a result,the demand for m-dichlorobenzene has been increasing year after year,and the supply of products exceeds the demand,and the development prospects are broad.In the industry of m-dichlorobenzene,the mixed dinitrobenzene is the main raw material.The m-dinitrobenzene can be obtained by sulfonation method.The m-dinitrobenzene can be obtained by chlorination.This method will produce a lot of organic wastewater and seriously pollute the environment.Based on previous research,the methoxygenation reaction is selected to purify the raw materials,which improves the efficiency of the raw materials utilization of raw materials.The study on the preparation of m-dichlorobenzene by photocatalysis chlorination of m-dinitrobenzene was carried out in a circulating reactor,which is of great practical significance for industrial production.In this paper,the effects of various reaction conditions on the purification of m-dinitrobenzene by methoxylation of mixed dinitrobenzene and the photocatalytic chlorination of m-dinitrobenzene were studied by single factor experiments.The optimum reaction conditions were explored by laboratory methods.The optimal reaction conditions of raw material purification process were as follows: methanol was selected as the reaction solvent,the molar ratio of o-dinitrobenzene,p-dinitrobenzene and sodium methoxide was 1:1.05,the mass ratio of mixed dinitrobenzene and methanol was 1:0.3,the reaction temperature was maintained at 76℃,the dropping time of sodium methoxide was controlled at 30 min,the stirring reflux reaction time was 50 min,and the stirring rate was 200r/min After drying,m-dinitrobenzene was obtained.The purity of m-dinitrobenzene was 99.9%,and the conversion of o-dinitrobenzene and p-dinitrobenzene was over 99.8%.The reaction conditions for the preparation of m-dichlorobenzene by photocatalytic chlorination were as follows: the light source was 25 W ultraviolet lamp,the reaction temperature was 160℃,the reaction time was 9h,and the chlorine gas flow rate was controlled at 210ml/min.the crude product of m-dichlorobenzene was prepared under the reaction conditions.The m-dichlorobenzene was separated and purified by distillation unit,the vacuum degree was-0.097 Mpa,and the reflux ratio was controlled at about 12.By gas chromatography analysis,the yield of m-dichlorobenzene is 91.2%,and the purity of m-dichlorobenzene after distillation is99.9%,which meets the product quality requirements.