Synthesis And Process Optimization Of Clethodim

Herbicides are one of the most important means to control weeds in farmland. With the development of herbicide, cyclohexenone herbicides have good prospects in the field of weeding because of their highly selectivity and the ability of controlling a variety of grassy weeds. Clethodim as a typical cyclohexenone herbicide, has been widely applied in weeding. Because it has the advantages of high efficiency, low toxicity, broad-spectrum weed control and safety for the crop.In this paper, an efficient rout to prepare clethodim was investigated according to the previous methods. Firstly, crotonaldehyde reacted with ethanethiol to give3-ethylthiobutanal. Secondly, ethyl acetoacetate was converted to6-ethylthio-3-ene-2-heptanone via hydrolysis, condensation with3-ethylthiobutanal and dehydration. Then6-ethylthio-3-ene-2-heptanone reacted with dimethyl malonate by Michael addition and Claisen condensation, followed by saponification and decarboxylation reaction to generate5-[(2-ethylthio)propyl]-3-hydroxyl-2-cyclohexen-l-one, which was propylaeylated to give5-[2-(ethylthio)propyl]-2-propionyl-3-hydroxyl-2-cyclohexen-1-one. Finally, clethodim was obtained by the reaction of trione with3-chloropropenyl-oxyamino. The target product and all the intermediates were characterized by1H-NMR or MS.Moreover, all steps were selected to further optimize the conditions, particularly of the dehydration reaction and the acylation reaction. The method provide several advantages, such as simpler procedures, lower cost and higher yields, thereby offering considerable potential for industry operation..