Study On The Synthetic Process Of Cyhalofop-Butyl

Pesticides promote the development of agriculture,Aryloxyphenoxypropionate(APP)herbicides have been invented to be one of the optical active herbicides for the control of annual and perennial grasses in broadleaf crop field in the last forty years.Aryloxyphenoxypropionate herbicides with high efficiency,low toxicity,low residue,high selectivity,have been developed vigorously.Cylaofop-butyl is an aryloxyphenoxypropion-ate herbicides with high safety,it is highly effective to eradicate gramineae weeds.The only effective type of cyhalofop-butly is the(R)-isomer.This dissertation is focused on process research synthesis of cyhalofop-butyl.In the present paper,synthetic methods of cyhalofop-butyl were reviewed in detail.This paper focuses on the disadvantages and advantages of the synthetic routes and makes plans for a new synthetic process for industrial production.(S)-2-Chloropropionic acid was synthesized from staring material L-alanine through diazotization.(S)-2-Chloropropionic acid reacted with hydroquinone to give(R)-2-(4-hydroxyphenoxy)-(R)-2-(4-hydroxyphenoxy)propionic acid,which was esterified with butyl alcohol to give butyl(R)-2-(4-hydroxyphenoxy)propionate.Finally cyhalofop-butyl was synthesized from butyl(R)-2-(4-hydroxyphenoxy)propionate and 3,4-difluorobenzonitrile.The optimal conditions such as reactant proportion,reacting temperature and reacting time,ect.have been found through a mumber of tests.The total of the product yield was 44.2%and the purity was 98.5%,ee%94.2%.Meanwhile the problems in each of the reaction and side reactions were studied and discussed.The synthetic process has some advantages of high yield,simple operation and high purity,and is suitable for industrial production.The chemical structures of cyhalofop-butyl and intermediates had been characterized by ~1H-NMR.