Characterization of Chlorovinylcobalamin, A Putative Intermediate in Reductive Degradation of Chlorinated Ethylenes

Abstract

The first X-ray structure of a vinylcobalamin is reported. Chlorovinylcobalamin is formed in the reaction of cob(I)alamin with chloroacetylene. Subsequently, cob(I)alamin catalyzes the reduction of chlorovinylcobalamin to vinylcobalamin in the presence of excess titanium(III)citrate. Introduction of a chlorine onto the vinyl group of vinylcobalamin greatly changes its reduction potential. These results are discussed with respect to vitamin B12-catalyzed dechlorination of perchloroethylene, a pollutant on the priority list of the EPA.