The reactions of diazomethane, introduced as the gas over extended periods (1.5-3 hr.), with bromopolychloromethanes (or 1-bromo-l, l-dichloroethanes) under irradiation give a series of products of successive interpositions of methylene-initially between chlorine and carbon, and finally between bromine and the same carbon. For these examples, the previously suggested free-radical chain mechanism must be modified to propose attack by ...