Dehalogenation of lindane by a variety of porphyrins and corrins

The dehalogenation of lindane by a range of hemoproteins, porphyrins, and corrins has been tested under reducing conditions in the presence of dithiothreitol. In addition, a series of porphyrin-metal ion complexes have been prepared and have also been screened for the capacity to dehalogenate lindane. Hemoglobin, hemin, hematin, and chlorophyll alpha all catalyzed the dehalogenation of lindane, as did all of the corrins tested. The porphyrins which did not contain metal centers--coproporphyrin, hematoporphyrin, protoporphyrin, and uroporphyrin--were inactive. However, when these porphyrins were then complexed with Co, Fe, Mg, Mo, Ni, or V, lindane dehalogenation was observed. In all cases, the reaction proceeded by an initial dechlorination to produce tetrachlorocyclohexene, which was further dehalogenated to yield chlorobenzene as the end product.