Preparation method of MHA (2-hydroxy-4-(methylthio) butyric acid)

Abstract

The invention discloses a preparation method of MHA (2-hydroxy-4-(methylthio) butyric acid). According to the preparation method, nitrile generated by a reaction of a hydrocyanic acid aqueous solution and (methylthio) propionaldehyde is subjected to acidolysis and then treated to obtain an organic phase containing MHA and an aqueous phase containing ammonium salt, the organic phase is subjected to concentrating under reduced pressure and organic solvent treatment or is subjected to direct centrifugal treatment to remove ammonium salt, and MHA is obtained; and the ammonium salt can be further purified to obtain high-purity ammonium salt by-product, and brine waste is not generated. During the preparation process, the used organic solvent can be recycled for application, the used hydrocyanic acid aqueous solution has no tail gas incineration, hydrocyanic acid rectification is not required, and the energy consumption is low; and the organic phase and the aqueous phase are treated separately, compared with direct water removal without phase-splitting, the influence of the ammonium salt on water distillation is reduced, the condition that mass transfer and heat transfer during water distillation are affected by a great amount of ammonium salt is avoided, so that the water distillation quantity is reduced greatly while energy consumption is reduced, and steam is saved.

Description

technical field [0001] The invention belongs to the technical field of chemical industry, and in particular relates to a preparation method of 2-hydroxy-4-methylthiobutyric acid as a feed additive. Background technique [0002] 2-Hydroxy-4-methylthiobutyric acid (MHA), also known as methionine hydroxy analog, is the hydroxy homologue of the basic amino acid methionine in racemic form. In poultry feeding, 2-hydroxy-4- Methylthiobutyrate exhibits properties similar to amino acids known to play a growth-promoting role and has therefore become a major additive in animal feed. [0003] 2-Hydroxy-4-methylthiobutyric acid is mainly obtained by adding hydrocyanic acid (HCN) to methylthiopropionaldehyde to obtain 2-hydroxy-4-methylthiobutyronitrile, and then hydrolyzing the nitrile. The difference between the preparation methods in the prior art is mainly reflected in the difference in the physical state of the hydrocyanic acid used in the preparation process and the separation and ...

AI Technical Summary

Problems solved by technology

This production process has the characteristics of high yield of 2-hydroxy-4-methylthiobutyric acid, high monomer content and high purity of by-product ammonium sulfate. Too much ammonium sulfate at the time will affect the mass and heat transfer during steaming, especially when the final moisture is lower than 10%, the viscosity of the system will increase, the overall volume of steamed water will increase, and the energy consumption will increase

[0005] The above methods either have complicated process, low yield, high cost, high energy consumption, or large consumption of raw materials, many wastes, and difficult industrial implementation, resulting in high cost and serious environmental pollution of these methods in the expanded industrial production. Therefore, , it is necessary to improve the above method to become a reality

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