The chemical synthesis method of betaine, and investigates the effects of the feed ratio of chloroacetic acid, sodium hydroxide, and trimethylamine in the reactants, reaction temperature and time on the product content and yield were explored. The optimal reaction conditions were determined to be：n(chloroacetic acid)∶ n (sodium hydroxide)∶ n (trimethylamine)=1∶1.05∶1.1, dropped at room temperature of 20 ~ 25 ℃, kept for 60 minutes after dripping, continued to be heated to 50 ~ 55 ℃ for 60 minutes, and then heated again to 70 ~ 75 ℃ for 60 minutes. The mixed solution prepared by the reaction was desalination by electrodialysis membrane, achieving the separation of betaine and sodium chloride; After desalination, the mother liquor is concentrated, filtered, and dried to obtain the product betaine. After testing, the content reaches 99.2%, and the chloride ion content is less than 0.2%, meeting the feed grade betaine type I standard with a yield of 91.8%. It is far superior to traditional separation methods, with less equipment investment, economic and environmental protection, while avoiding the generation of a large amount of waste liquid.
