Glycine synthesis method

Abstract

The invention discloses a glycine synthesis method which comprises the following steps: adding mother liquor, silicone oil and a crystallization aid into a reaction kettle, and heating the reaction kettle to 75-85 DEG C, wherein the mother liquor contains an alcohol-water system and urotropine; dropwise adding a chloroacetic acid solution into the reaction kettle, introducing ammonia gas into thereaction kettle at the same time, ensuring that the pH value is 6.5-8, and keeping the temperature for 20-40 minutes in the reaction process; after the reaction is finished, centrifugally separating out a mixed crystal containing glycine, and leaving mother liquor containing impurities and a byproduct ammonium dichloroacetate; and separating glycine from the mixed crystal, feeding the mother liquor containing impurities and the byproduct ammonium dichloroacetate into a degumming kettle, changing the magnetic field of the mother liquor, and removing the byproduct ammonium dichloroacetate and impurities by using an alcohol precipitation method to obtain the mother liquor. According to the method, the crystal form granularity and the wall scraping phenomenon are effectively controlled, meanwhile, the solvent content in the mixed crystal is controlled, urotropin and impurities are effectively separated in the synthesis process, and urotropin and impurities are prevented from entering the mixed crystal separation process.

Description

technical field [0001] The invention relates to a synthesis method of glycine. Background technique [0002] At present, glycine is the amino acid with the simplest structure and the smallest molecular weight. It is widely used in the fields of medicine, food, feed and chemical industry, and is the main raw material for the production of herbicide glyphosate. The synthesis methods mainly include Streck method, Bucherer method, phase transfer catalysis method and chloroacetic acid ammonolysis method, and domestically, chloroacetic acid ammonolysis method is the main method. [0003] 70% of domestic production capacity of glycine is used to produce glyphosate, and the quality of glycine directly determines the quality of glyphosate. Generally, the production of glyphosate requires the purity of glycine to be ≥ 98.5%, and the cl- content to be ≤ 0.4%. However, the current domestic production process of glycine has the following disadvantages: [0004] 1. Large amount of mothe...

AI Technical Summary

Problems solved by technology

In the current domestic production process, urotropine is mixed in ammonium chloride, and the temperature when ammonium chloride is distilled and concentrated is 180°C. This temperature causes the degradation of urotropine to turn yellow, and formaldehyde is produced after the degradation of urotropine. It has a bactericidal effect, which seriously affects the quality of ammonium chloride. In addition, urotropine cannot be reused, resulting in waste of resources;

[0006] 3. Low yield

But the crystal that occurs rapidly releases heat of crystallization, easily forms peritectic and wall phenomenon, causes the pH value in the reaction solution to be unequal, and then causes urotropine to be degraded with pH value change (especially when pH≤6), thereby Affect the yield of the reaction and a large amount of impurities, causing difficulties in the mixed crystal separation process

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