Continuous flow preparation method of clethodim intermediate 5-[2-(ethylthio) propyl]-2-propionyl-3-hydroxy-2-cyclohexene-1-ketone

The invention belongs to the technical field of organic chemical engineering, and particularly relates to a continuous flow preparation method of a clethodim intermediate 5-[2-(ethylthio) propyl]-2-propionyl-3-hydroxy-2-cyclohexene-1-ketone. The preparation method comprises the following steps: mixing a toluene solution of 5-[2-(ethylthio) propyl]-3-hydroxy-2-cyclohexene-1-ketone and triethylamine with a toluene solution of propionyl chloride; conveying to a multi-stage oscillation reactor, and carrying out acylation reaction to obtain a preliminary 5-[(2-ethylthio) propyl]-3-ketone-1-cyclohexene-1-propionate product and a suspension of triethylamine hydrochloride; separating out triethylamine hydrochloride and a reaction solution through a liquid storage tank; and then mixing with a toluene solution of DMAP (4-dimethylaminopyridine), feeding the mixture into a microchannel reactor, and carrying out Fries rearrangement to obtain the final product 5-[2-(ethylthio) propyl]-2-propionyl-3-hydroxy-2-cyclohexene-1-