Catalytic aqueous reductive dechlorination of chlorinated ethylenes with a water soluble cobalt porphyrin

Chlorinated ethylenes, (CE), specifically perchloroethylene (PCE) and trichloroethylene (TCE), are widespread groundwater pollutants listed as EPA priority pollutants. The catalytic dechlorination of CE by a water soluble porphyrin, tetrakis-(4-carboxyphenyl)-porphyrin cobalt, (TCPP)Co, was studied and had superior aqueous phase dechlorination activity. The CE dehalogenation catalytic cycle was elucidated with kinetic, spectroscopic, and synthetic studies. The Co^I porphyrin species was active for dehalogenation through studies with UV-visible absorbance spectroscopy and cyclic voltammetry. Evidence for chlorovinyl complexes as potential catalytic cycle intermediates was obtained through the preparation of (TPP)Co(trans-C₂H₂Cl) and (TPP)Co((Z)-C₂HCl₂) and the observation of (TCPP)Co(C₂HCl₂) by MS. This is an abstract of a paper presented at the 230th ACS National Meeting (Washington, DC 8/28/2005-9/1/2005).