Synthetic method of malononitrile

Abstract

The invention discloses a synthetic method of malononitrile. Cyanoacetamide reacts with triphosgene in the presence of a catalyst to synthesize malononitrile, wherein the catalyst is any one substance or a mixture of multiple substances selected from N,N-dimethyl formamide, sodium chloride, pyridine and triethylamine. The method provided by the invention employs the triphosgene as a dehydrating agent, and the triphosgene is low in cost, available and high in stability, and facilitates storage and transportation; the reaction products of the cyanoacetamide and the triphosgene only include carbon dioxide and hydrogen chloride gases except for the malononitrile, without solid waste, and therefore, after the reaction is completed, the steps of removing the solid waste by means of filtering, centrifuging and the like are not needed; the reaction mixture is directly subjected to reduced pressure distillation after the solvent is recovered so that the malononitrile having the purity of higher than 98% can be obtained; and the posttreatment is simple.

Description

technical field [0001] The invention belongs to the field of chemical industry and relates to a synthesis method of malononitrile. Background technique [0002] Malononitrile is an important raw material for organic synthesis and an important intermediate for the synthesis of drugs (such as vitamin B1, triamterene, adenine, etc.) . At the same time, malononitrile also has important uses in synthetic dyes, metal anticorrosion, and resin crosslinking agents. [0003] There are many synthetic methods of malononitrile, including cyanoacetamide dehydration method, allene oxidation ammonolysis method, acetonitrile cyanamide gas phase method, acetonitrile high temperature pyrolysis method, acrylonitrile and aminoacetonitrile method, etc. Among them, the cyanoacetamide dehydration method is a common method for synthesizing malononitrile because of its simple route, cheap and easy-to-obtain raw materials, mild reaction conditions, low process requirements, simple equipment, and few...

AI Technical Summary

Problems solved by technology

[0004] In the preparation of malononitrile by the dehydration method of cyanoacetamide, the commonly used dehydrating agents are phosphorus oxychloride, phosphorus pentachloride and phosphorus pentoxide, but the use of the above dehydrating agents has the following disadvantages: a large amount of phosphorus containing solid waste, and these phosphorus-containing solid wastes are relatively viscous and easy to stick to the reactor wall. Usually, it is necessary to add carriers such as sodium chloride, diatomaceous earth, silica gel, and calcium chloride to the reaction system for adsorption, thereby further increasing The amount of solid waste generated; at the same time, these solid wastes need to be removed by filtration, centrifugation and other means after the reaction, which also makes the post-processing operation more cumbersome

Although this method does not produce phosphorus-containing solid waste, and the obtained by-product cyanuric acid can be used as antifouling agent or marine insecticide, it still needs to filter and separate the by-product, and the post-treatment operation is still relatively complicated, and the dehydrating agent cyanuric chloride is in the air. Medium unstable, volatile, inconvenient for storage and transportation

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