Process for preparing r-(+)-2-chloropropionic acid with high optical purity by transesterification

Abstract

The invention discloses a process for preparing high-optical-purity R-(+)-2-chloropropionic acid through an ester exchange method. The process comprises the following steps: placing ethyl chloropropionate in a reactor, sequentially adding formic acid with the mass fraction of 94% and strong-acid cation exchange resin under stirring, slowly heating to 54DEG C, extracting ethyl formate, continuously heating, and recovering formic acid; and forming a negative pressure after the recovery of formic acid, and extracting R-(+)-2-chloropropionic acid. The process has the advantages of simple technology, no strong acidic tails, environmental protection and short production period, and the optical purity and the yield of the prepared R-(+)-2-chloropropionic acid are not smaller than 99% and not smaller than 90% respectively.

Description

technical field [0001] The invention relates to a preparation method of intermediates such as pesticides, dyes, medicines and nutritional supplements, and in particular to a preparation method of R-(+)-2-chloropropionic acid with high optical purity by transesterification. Background technique [0002] R-(+)-2-chloropropionic acid is one of the important intermediates in the synthesis of pesticides, dyes, medicines, nutritional supplements, etc. Its application involves many fields of the national economy and people's daily life. It is an important product . Because optical enantiomers are different in biological activity, toxicity, pharmacology, etc., the preparation of single enantiomers is extremely important. In recent years, the chiral pharmaceutical market has developed rapidly, and the research and application of single enantiomer drugs are also More and more important, so it is of great significance to prepare R-(+)-2-chloropropionic acid with high optical purity. ...

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Problems solved by technology

[0003] CN103435469A provides a kind of preparation method of preparing high optical purity R-(+)-2-chloropropionic acid, utilizes 10% sulfuric acid to hydrolyze 2-chloropropionic acid methyl ester, and its yield is 86%, has not been reported in the patent Its optical purity; but it is hydrolyzed with sulfuric acid, the oxidizing property is too strong, the corrosiveness is too strong, it is easy to oxidize carbon-containing compounds when the temperature rises, and the raw materials are lost, the reaction liquid becomes viscous, the yield is reduced, and isomerism occurs body, affecting its optical purity; and the carbon compounds produced hinder the reaction, and are difficult to handle, polluting the environment, and there are a large number of by-product tails that need post-processing

However, using sodium hydroxide to hydrolyze under alkaline conditions produces more chiral impurities, and the total yield is only 61.93%. The yield is too low and the cost of industrial production is high.

There is also a chromatographic resolution method, which mainly adopts the separation of 2-chloropropionic acid optical isomers on the chirality of cyclodextrin or cyclodextrin derivatives. This type of method is mainly used for analysis and detection, and is not suitable for industrial use. Production

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