Dichloroacetaldehyde

an intermediate of organic insecticide

can be synthesized by the catalytic chlorination of paraldehyde or aldehyde. The selection of catalysts

the temperature of various stages of the reaction

etc.

were investigated and dichloroaldehyde was obtained in good yields. The experimental results indicate that antimony trichloride is more active than sulfur for catalytic chlorination of paraldehyde or aldehyde. It is necessary to control the reaction temperature

the quantity of catalyst and the molar ratio of the reactants accurately. The product

containing 90~95% of dichloroacet-aldehyde

was obtained in 75~78% yields. Formation of tarry distillation residue due to the polymerization increases with the increasing of the reaction temperature or the quantity of antimony trichloride.