A quantum chemical study of unexpected reaction of α-chloroacyl chlorides with 1,2-dichloroethylene in the presence of aluminum chloride

Abstract

The reactions of acetyl chloride and chloroacetyl chloride with 1,2-dichloroethylene in the presence of aluminum chloride have been mechanistically studied at the M06/6-311+G(d,p) level of theory. The reaction with acetyl chloride proceeds via the classical channel to afford the expected 1,2-dichlorovinyl ketone. The reaction with chloroacetyl chloride occurs through the alternative channel delivering dichloromethyl-2-chlorovinylketone instead of anticipated chloromethyl-1,2-dichlorovinylketone. The quantum-chemical calculations have shown that the difference between classical and alternative channels is due to the competitive processes occurring at the first stage of the reaction, namely formation of adducts and elimination of hydrogen chloride. In the reaction involving acetyl chloride, the first channel is kinetically more favorable, whereas in the reaction with participation of chloroacetyl chloride, the second channel becomes preferable.