Method for continuously rapidly synthesizing 2-hydroxy-4-methylthio butyronitrile

Abstract

The invention provides a method for continuously rapidly synthesizing 2-hydroxy-4-methylthio butyronitrile. The method comprises the following steps: mixing methylthiopropanal containing a catalyst with hydrocyanic acid liquid through a static mixer, then feeding the mixture into a microchannel reactor for reaction, controlling the reaction temperature to be 30 to 70 DEG C and the pressure to be 0.05 to 0.5MPa, and ensuring that the total residence time of a reaction mixture in a micro channel is 0.5 to 10min to obtain the 2-hydroxy-4-methylthio butyronitrile. By adopting the method, the reaction time of the methylthiopropanal and hydrocyanic acid and the residence time of a cyanohydrin product are greatly shortened by enhancing dispersion contact of heterogeneous materials through premixing of the static mixer and decomposing reaction volume through a microreactor, the production of by-products during reaction is reduced, clear and high-purity cyanohydrin products are obtained, and continuous preparation of high-quality methionine is facilitated; and meanwhile, the utilization of hydrocyanic acid is improved, and the yield of products is improved, so that certain reduction of theproduction cost is realized.

Description

Technical field [0001] The invention relates to the field of chemical engineering, 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 with hydrocyanic acid (hydrogen cyanide) under the action of a catalyst. Suitable catalysts are pyridine and triethylamine. The methionine hydroxy analogue (liquid methionine for short) is obtained by the hydrolysis of cyanohydrin and inorganic acid such as sulfuric acid, and the cyanohydrin reacts with ammonium bicarbonate or an aqueous solution of carbon dioxide and ammonia to form 5-(2-methylthioethyl)-hydantoin Urea (hydantoin for short), which can be hydrolyzed with inorganic bases such as sodium hydroxide or potassium carbonate or potassium hydroxide to obtain methionine. [0004] It is known from, for example, the patent USA496093...

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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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