Study On The Synthesis Of R-Metalaxyl

Metalaxyl, the chemical name for the D, L-N-(2,6–dimethylphenyl) - N-(methoxy-acetyl) ester. rock crystal, the melting point of 71.8 to72.3℃, preparations for white or beige powder. It was developed by the company Ciba– Jiaji of Switzerland in 1977. It is a new, highly efficient, low toxicity to prevent and treat gang diseases, Systemic Fungicide, and have effects for the variety of crops and downy mildew epidemic Mold.Metalaxyl is raceme. Studies show that the active of R-isomer is 20 to 30 times higher than the S-isomer and even 100-fold in some areas. When applied outside raceme, the active of R-isomer is reduced by S-isomer, which has the opposite effect. R-isomer is more bactericidal activity and its efficacy is longer, It reduces the number of application and extends the application period, the amount of metalaxyl is only 62% of the racemate. At the same time, the degradation of R-isomers is faster than the mixed spin's in the environment, has a better environment compatibility. Synthesis of single metalaxyl R-isomer has important significance on reducing the dosage and increasing efficacy.In this paper, the intermediates of methyl 2 -(2, 6-dimethylphenyl) alanine and methoxy-chloride first were synthesized, and then the metalaxy was synthesized by the reaction of replacing.In the synthesis process of intermediates methyl 2 -(2, 6-dimethylphenyl) alanine selection of 2,6 - dimethylaniline and 2 - bromopropionaldehyde in the presence of tied acid methyl ester, Optimized the temperature and time of the reaction, lashing the choice of acid conditions. Determine the best reaction conditions for the use of pyridine tied acid, a mild reaction conditions were a high yield. Methyl 2-(2, 6-dimethylphenyl) alanine selected in the process of Pseudomomas sp. Lipase, PSL, Candida antarctia Lipase, CAL-B lipase two kinds of methyl 2 -(2, 6-dimethylphenyl) alanine to split research, the two split on the results of comparison, the use of the PSL subdivides access to the S- 2-(2, 6-dimethylphenyl) alanine and R-2-(2,6 - dimethyl-phenyl) propionic acid. Both have high e.e.p% value.In the process of S-2 -(2, 6-dimethylphenyl) alanine racemization, using microwave and conventional heating two ways, the use of aldehydes and organic acid racemization of their research. Initially get an effective method of racemic by optimizing time, reagents and the heating temperature of the reaction.Through this study, basically complete the optical pure metalaxyl small test synthesis work, and lay the foundation for industrial production of the R configuration metalaxyl.