The invention relates to the technical field of
organic synthesis, in particular to a synthesis method of high-purity clethodim, which comprises the following steps: mixing modified
crotonaldehyde and modified
methyl acetoacetate for
condensation reaction to prepare intermediate feed liquid; introducing
nitrogen into the intermediate feed liquid for protection and
dehydration to prepare a dehydrated intermediate; carrying out
acylation and transposition reaction on the dehydrated intermediate to prepare propionyl
triketone feed liquid; mixing a propionyl
triketone feed liquid with the modified chlorinated allyloxyamine, adding a stabilizer, carrying out oximation reaction in a fourth microchannel reactor, and after the reaction is finished, carrying out cooling recrystallization, filtering and
drying post-treatment to obtain the high-purity clethodim. By adopting a microchannel reactor
continuous flow process and combining
targeted modification treatment on three raw materials, namely
crotonaldehyde,
methyl acetoacetate and chloro-allyloxyamine, the conversion efficiency of each step of reaction is improved, the
reaction conditions are mild, the process is controllable, the product purity is relatively high, the yield is stable, and meanwhile, side reactions are reduced.