Mechanistic aspects of chlorinated ethylene degradation by vitamin B12

Chlorinated organic molecules constitute the largest single group of compounds on the list of priority pollutants compiled by the EPA. Among these compounds are tetrachloroethylene (PCE) and trichloroethylene (TCE), widely used solvents that are abundant pollutants of soil and ground water. Catalytic amounts of vitamin B12 in the presence of Ti(III)citrate can reductively dechlorinate PCE and TCE to dichlorethylenes (DCE). To distinguish between these various mechanistic possibilities, X-ray crystallographic, kinetic, and computational approaches are used. These studies suggest an electron transfer pathway for the reduction of PCE to TCE, and the intermediacy of organocobalt complexes in the dechlorination of TCE and DCE. This is an abstract of a paper presented at the 230th ACS National Meeting (Washington, DC 8/28/2005-9/1/2005).