| The preparation of single enantiomer is important for the disaffinity of bioactivity, toxicity and mechanism of metabolizability between enantiomers. Recent years the chiral medicine market is growing bigger and the study and application of single enantiomer pesticides are important because the environmental protection needs higher performance and higher purity of pesticides. As a important chiral intermediate of medicines and pesticides, 2-chloropropionic acid is indispensable to synthesize aryl.oxy.propionic acid herbicides, regulator of plant growth and antiseptics. Furthermore, the degree of optical purity of pesticides is osculating with the degree of chiral intermediate. Obviously, the synthesis and application of (S)-2-chloropro- pionic acid have important meaning.In this paper, (S)-2-chloropropionic acid was studied in two aspects: optimization to synthesis and chiral analysis. First, there are not an accurate density and specific rotation and relative e.e. value of 2-chloropropionic acid. No one has proved that 2-chloropropionic acid can be directly separated by using chiral stationary phase. So we studied that 2-chloropropionic acid was preliminarily derivatized with 1-naphthylamine at 30℃for 10 minutes, then the derivatives was satisfactorily separated in 8 min by using Chiralcel OD-H column and hexane-alcohol eluent. The effects of composition of mobile phase and column temperature on the chiral separation were investigated. The optimal analysis conditions were obtained as: mobile phase hexane-carbinol-ethanol(50:45:5, V/V), flow rate 1.0ml·min-1, temperature 30℃and wavelength 224nm. More accurate standard specific rotation of 2-chloropropionic acid and relative e.e. value are [α]D20-13.94(neat, d1.2547) and e.e.97.9％. This method is proved to be sensitive, easy for operation and good for accurate optical purity measurement of 2-chloropropionic acid.Based on these studies, the chiral optimization to synthesis was stusied. Optically pure (S)-2-chloropropionic acid was synthesized from cheap material L-alanine. The optical purity of product was 95％～98％and yield achieved 65％. The reaction conditions were studied in these aspects: (1) The yield was improved to 65％by changing material ratio; (2) The optimal ice/sodium chloride bath reaction time was 3.5h by using reversed phase HPLC; (3) Using normal phase HPLC, the effect of reaction room temperature on optical purity was studied and found that 20℃was good for the synthesis.In the end, we studied how to synthesize (S)-2-chloropropionic acid from another cheap material L-lactic acid. The optical purity of 2-chloropropionic acid achieved 90％and yield was 45％through 3 step reactions. It proves a new possible method to synthesize (S)-2-chloropropionic acid.
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