Synthesis and Characterization of 4-Ethoxy-2,3-difluoroacetophenone

The liquid crystal intermediate 4-ethoxy-2,3-difluoroacetophenone of a purity of more than 99% was synthesized via Friedel-Crafts reaction with 2,3-difluoroethoxybenzene and acetyl chloride as starting materials.The target compound was characterized by means of 1HNMR,IR and GC-MS.When dichloromethane was used as reaction solvent,the molar ratio of 2,3-difluoroethoxybenzene/aluminium chloride/acetyl chloride was 1∶ 1.14∶ 1.3,the reaction temperature was-10~-5 ℃ and the reaction time was 1 h,the reaction results was best,with the mass ratio of the main product being 89.2%,the mass ratio of 2,3-difluoroethoxybenzene being 4.83%,the mass ratio of 4-acetyl-2,3-difluorophenyl acetate being 0.12% and the content of the isomers of the product being not detected.The generation reason of the by-products during Friedel-Crafts reaction was proposed according to the results of the experiments.