Method for synthesizing dichloroacetonitrile

Abstract

The invention discloses a method for synthesizing dichloroacetonitrile. The method comprises the following steps of adding dichloromethane into tetrachloroethylene, then slowly introducing ammonia gasinto a dichloromethane-tetrachloroethylene system for pressurization, using water bath for temperature rising, maintaining the temperature and the pressure for a reaction, and after the reaction is finished, lowering the temperature; meanwhile, removing residual ammonia gas and collecting fractions through distillation to obtain dichloroacetonitrile. According to the method, a new synthesis routeis adopted for preparing dichloroacetonitrile serving as a florfenicol raw material. A process for generating dichloroacetonitrile through the pressurization reaction between tetrachloroethylene andammonia gas, compared with a traditional dichloroacetic acid production process, has the advantages that the process is simple, no phosphorus-containing wastewater is generated, and no bromine elementis introduced for post-treatment. The yield and purity of a product are both improved, the generation of three kinds of waste is avoided, and the method has a good industrialization prospect.

Description

technical field [0001] The invention belongs to the technical field of organic chemical production, in particular to a method for synthesizing dichloroacetonitrile as a raw material of the veterinary drug Florfenicol. Background technique [0002] Dichloroacetonitrile is the raw material needed for the production of the national second-class new veterinary drug Florfenicol. Effective treatment of infections and enteric infections, especially in food-producing animals. Florfenicol will replace chloramphenicol and has broad application in veterinary medicine. [0003] The molecular structural formula of dichloroacetonitrile is shown in the following formula: [0004] [0005] At present, the preparation of dichloroacetonitrile at home and abroad mainly contains the following two synthetic methods: [0006] The first is to use dichloroacetic acid (the production corner material of chloroacetic acid, the chlorinated product of chloroacetic acid) as the initial raw material...

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Problems solved by technology

The production method of this factory is relatively simple, and the raw materials are cheap, but the phosphorus-containing wastewater is difficult to solve, and the pressure on environmental protection is extremely high.

[0007] The second is Dibromoacetonitrile{OrganicSyntheses, Coll.Vol.4, p.254(1963); Vol.38, p1.6(1958).} It is mentioned in the literature that N-bromosuccinimide (N-chloro succinimide) reacts with cyanoacetic acid to obtain dibromoacetonitrile, and N-chlorosuccinimide has the same properties as N-bromosuccinimide, and dichloroacetonitrile can be synthesized in the same way. And this route yield is 75%~87%, and yield is lower and can produce bromide and bromine-containing waste water, and aftertreatment problem is comparatively troublesome, and environmental protection requirement is high, and pressure is big, and total yield is lower

[0008] The literature (Chlorination of Cyanoethanoic Acid in Aqueous Medium--Environ.Sci.Technol, Vol.24, No.1, 1990) mentions that in the reaction process of cyanoacetic acid and sodium hypochlorite, there will be dichloride in the gas phase detection at low pH value. Acetonitrile is produced, but there are many types of products produced by this method, and the content of the target product dichloroacetonitrile is small, and it only stays in the experimental stage, and there is a big gap from industrialization

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