A kind of method of continuous rapid synthesis 2-hydroxyl-4-methylthiobutyronitrile

Abstract

The invention provides a method for continuously and rapidly synthesizing 2-hydroxy-4-methylthiobutyronitrile, comprising: adding methional and hydrocyanic acid liquid containing a catalyst into a microchannel reactor after being mixed by a static mixer Carrying out the reaction, controlling the reaction temperature to be 30° C. to 70° C., the pressure to be 0.05 to 0.5 MPa, and the total residence time of the reaction mixture in the microchannel to be 0.5 to 10 minutes to obtain 2-hydroxy-4-methylthiobutyronitrile. The present invention enhances the dispersed contact of heterogeneous raw materials through static mixer premixing and uses the micro-reactor to decompose the reaction volume, realizes the reaction time of methionine and hydrocyanic acid and the residence time of cyanohydrin product greatly shortens, reduces The production of by-products in the reaction process is eliminated, and a clear and high-purity cyanohydrin product is obtained, which is conducive to the continuous preparation of high-quality methionine; at the same time, the utilization rate of hydrocyanic acid is improved, which increases the yield of the product, thereby achieving a certain production cost reduction.

Description

technical field [0001] The invention relates to the field of chemical industry, in particular to a method for continuously and rapidly synthesizing 2-hydroxy-4-methylthiobutyronitrile. [0002] technical background [0003] 2-Hydroxy-4-methylthiobutyronitrile, also referred to as cyanohydrin, is usually synthesized from methylthiopropionaldehyde and hydrocyanic acid (hydrogen cyanide) under the action of a catalyst. Suitable catalysts are pyridine and triethylamine. Hydrolysis of cyanohydrin and inorganic acid such as sulfuric acid to obtain methionine hydroxyl analogs (referred to as liquid methionine), and cyanohydrin reacts with ammonium bicarbonate or carbon dioxide, ammonia aqueous solution to generate 5-(2-methylthioethyl)-hydantoin Urea (hydantoin for short), which can be hydrolyzed with inorganic bases such as sodium hydroxide or potassium carbonate, potassium hydroxide to obtain methionine. [0004] From eg patent USA4960932 it is known to produce methionine by a f...

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Problems solved by technology

[0014] In view of the above-mentioned shortcoming of the prior art, the object of the present invention is to provide a kind of method for the continuous rapid synthesis of 2-hydroxyl-4-methylthiobutyronitrile, the method possesses atom economy, and is used to solve the problems in the prior art. When synthesizing 2-hydroxy-4-methylthiobutyronitrile, the reaction time is long, hydrocyanic acid is excessive and easy to polymerize, methylthiopropionaldehyde is thermally decomposed and polymerized, and by-products are easily produced, and the reaction rate is slow, resulting in the formation of colored impurities, Insufficient response, not economical and economical, resulting in waste of resources, not green and environmental protection, etc.

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