Method for preparing glycine by utilizing common ion effect

Abstract

The invention relates to a clean production process for preparing glycine in an alcohol-water mixed solvent by utilizing the common ion effect. A novel catalyst pyridine base compound or a traditionalcatalyst urotropine and paraformaldehyde is adopted as the catalyst. The method comprises the following steps: ammoniating ammonium chloroacetate in an alcohol-water mixed solvent under the conditionof a catalyst by introducing ammonia to synthesize glycine, carrying out centrifugal separation to obtain glycine, adding a solid chlorethamin into the mixed solvent obtained by centrifugation, cooling to 0-20 DEG C, and carrying out centrifugal separation to obtain ammonium chloride, and centrifugally separating ammonium chloride to obtain a circular reaction mixed solvent, and circularly carrying out a glycine synthesis reaction.

Description

technical field [0001] The invention relates to a clean production process of glycine, which uses the same ion effect to prepare glycine in an alcohol-water mixed solvent, and belongs to the technical field of chemical production. Background technique [0002] Glycine is an important raw material for products such as glyphosate and glycine ethyl ester hydrochloride, and it can also be refined into food-grade glycine for use. The traditional domestic aqueous phase chloroacetic acid ammonolysis method for glycine production process is as follows: Add an aqueous solution of about 25% catalyst urotropine into a reaction kettle with cooling water, and at the same time add about 80% of chloroacetic acid aqueous solution dropwise and pass it into Ammonia, the ammonolysis reaction is carried out at a pH value of about 7 and a reaction temperature of about 80°C. The ammonolysis reaction liquid containing glycine and ammonium chloride obtained after the reaction is separated by metha...

AI Technical Summary

Problems solved by technology

[0004] 1. The catalytic ability of urotropine is low, and the concentration requirement in the synthetic reaction aqueous solution is high. The production of one ton of glycine needs to consume about 150 kilograms of catalyst, and it is a one-time use and cannot be recycled;

[0005] 2. Urotropine is easy to decompose. Under high temperature or acidic conditions, urotropine will decompose into formaldehyde and ammonia.

[0007] 3. Wastewater containing urotropine, because it contains high concentration of formaldehyde, cannot be biochemically treated, and can only be treated by catalytic oxidation, which greatly increases the difficulty and cost of wastewater treatment

This scheme mainly has the following problems: firstly, the glycine product cannot be obtained directly in the glycine ammoniation reaction solution, only the mixed crystal solid of glycine acid and ammonium chloride can be obtained first, and the glycine product can only be obtained after subsequent treatment.

[0010] Patent CN1176062C introduces a method for producing glycine by the alcohol phase method. Although the catalyst can be recycled, the mixed crystal solid of glycine and ammonium chloride obtained by the reaction has no good separation method, and only electrodialysis or alcohol can be used. separation by means of analysis consumes a large amount of energy