Synthesis method of m-dichlorobenzene

Abstract

The invention relates to a synthesis method of m-dichlorobenzene, which is obtained by translocation reaction with dichlorobenzene as a raw material under the action of a catalyst, wherein the catalyst is an ionic liquid including Lewis acid and onium salt chloride. The synthesis method of the present invention uses an ionic liquid composed of a Lewis acid and an onium salt chloride as a catalyst,the selectivity of the reaction is above 90%, the yield can be significantly increased to above 60%, no under-pressure reaction is required, the reaction conditions are mild, the requirements for equipment are low, the catalyst can be reused many times, the amount of the three wastes is small, the environment is friendly, and the industrial production is suitable.

Description

technical field [0001] The invention belongs to the field of fine chemicals, and in particular relates to a synthesis method of m-dichlorobenzene. Background technique [0002] As an important intermediate in organic synthesis, m-dichlorobenzene is widely used in medicine, pesticide and dyestuff industries. In medicine, m-dichlorobenzene is used to synthesize antifungal drugs (such as miconazole, ketoconazole, etc.) Agents (such as propiconazole, hexaconazole, etc.) and herbicides, such as oxaconazole; in terms of dyes, m-dichlorobenzene is mainly used for the synthesis of naphthol AS-ITR, etc. It can be seen that m-dichlorobenzene has a good application prospect. [0003] The existing preparation process of m-dichlorobenzene mainly contains the following: [0004] 1. Nitrification and chlorination process: benzene is first nitrated to generate m-dinitrobenzene, and m-dinitrobenzene is then chlorinated under high temperature conditions to generate m-dichlorobenzene. Due t...

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Problems solved by technology

The nitrification reaction in this process is dangerous to a certain extent, and a large amount of by-products such as waste sulfuric acid, nitroxyl chloride and nitrosyl chloride are produced during the production process, which not only corrodes the equipment greatly, but is also extremely unfriendly to the environment. Increasingly, the process will gradually be eliminated

[0005] 2. Dichlorobenzene transposition process: The isomers of m-dichlorobenzene are used to generate m-dichlorobenzene through catalytic isomerization reaction. According to different catalysts, it can be divided into the following three processes: 1. The catalyst is Lewis Acid aluminum trichloride, advantage is that yield (about 50%) and selectivity are higher (about 90%), and shortcoming is that reaction is homogeneous reaction, and processing catalyst can produce a large amount of waste acid water, and environment is not friendly; Two, catalyst It is a salt melt of aluminum trichloride and lithium chloride, which has the same advantages of high yield and selectivity, but the reaction requires a certain pressure to proceed, and the mechanical reaction requires the introduction of HCl gas, which requires high equipment and salt melting The number of times of solid reuse is limited, and it is more difficult to handle after becoming solid waste; three, the catalyst is ZSM-5 molecular sieve, the advantage of this catalyst is that it is environmentally friendly, and the disadvantage is that the yield is not high (about 40%) and the selectivity is low (80%) %), the reaction requires high temperature and high pressure, high requirements on equipment, and the catalyst activation conditions are also relatively harsh

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