Synthetic method of high-purity and high-yield L-2-chloropropionic acid

Abstract

The invention discloses a synthetic method of L-2-chloropropionic acid. The synthetic method comprises the steps of firstly dissolving L-alanine into hydrochloric acid, introducing nitrosyl chloride and hydrogen chloride gas for reaction, after the raw materials are converted, filtering, continuing to stir for 1-2 hours, and an alkaline reagent for neutralization, extracting by virtue of an organic solvent, combining organic phases, drying by virtue of anhydrous calcium chloride, filtering, and carrying out rectification, so as to obtain a product, namely L-2-chloropropionic acid. The method has the advantages that the operation is simple, and the emission of wastewater is reduced; and by taking nitrosyl chloride with relatively high activity as a diazotization regent, aliphatic amino canbe rapidly converted into chlorine, so that the raw material conversation rate and the yield are greatly increased, the yield can reach 90% or above, an original configuration is not reversed in the reaction process, and the optical purity ee value can reach 99.1%.

Description

technical field [0001] The invention belongs to the field of fine chemical industry and relates to a method for synthesizing L-2-chloropropionic acid with high purity and high yield. Background technique [0002] L-2-chloropropionic acid is a key intermediate for the preparation of phenoxy series herbicides, Dexibuprofen, and high-2,4-dipropionic acid herbicides. Its enantiomers exist in the form of competitive inhibitors, which will not only reduce the efficacy of the pesticide, but also reduce the quality of the pesticide, produce toxic and side effects, and lead to phytotoxicity or drug resistance. Therefore, L with higher optical activity is synthesized. -2-chloropropionic acid is of great importance. [0003] At present, the method for synthesizing L-2-chloropropionic acid mainly contains the following kinds: [0004] Method 1: Use propionic acid as a raw material, chlorinate with chlorine gas to obtain racemic 2-chloropropionic acid, and then split to obtain opticall...

AI Technical Summary

Problems solved by technology

The traditional diazotization reaction uses the hydrochloric acid / sodium nitrite reaction system. First, the nitrosyl ion generated attacks the amino group with a lone pair of electrons, and generates chlorine azide through electron pair transfer, and then the temperature rises to release nitrogen gas to form a product. The aliphatic amino group is relatively active in the aqueous solution and can be easily converted into a hydroxyl group. The diazonium reaction of L-alanine in this system can only generate about 70% of the product