Vitamin B<sub>12</sub>, or cobalamin, is a tetrapyrrolic cofactor characterized by its cobalt metal center. It is found in three classes of enzymes, including the reductive dehalogenases that catalyze the dechlorination of organohalides. Chlorinated hydrocarbons are ubiquitous in industry, but they are also associated with health hazards. For example, trichloroethylene was recently identified as a carcinogen, and it has been detected in ground water and aquifers throughout the United States. We are investigating the mechanism of dechlorination through the synthesis and characterization of biomimetic cobalt. We synthesized [Co(TMC)(Cl)]Cl from tetramethylcyclam and cobalt chloride hexahydrate in a nitrogen atmosphere, and the reaction product was characterized by UV-visible spectroscopy, X-ray crystallography and elemental analysis. The reaction of [Co(TMC)(Cl)]Cl with tetrachloroethylene was monitored by UV-vis spectroscopy, and products from the headspace were identified using solid-phase microextraction (SPME) in conjunction with gas chromatography mass spectrometry. Qualitative analysis revealed that tetrachloroethylene could be dechlorinated to trichloroethylene.

Development of a biomimetic catalyst for dechlorination reactions

251st National Meeting (2016)

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