On the formation of benzenediazonium chloride in Gomberg–Hey type reactions of diazonium salts with bromotrichloromethane, carbon tetrachloride, and chloroform. The solution of a long-standing mechanistic puzzle

Abstract

A mechanism is offered for the formation of benzenediazonium chloride from the diazonium acetate in bromotrichloromethane and other polyhalogenomethanes, and of ‘anomalous’ halogen abstractions involving diazonium salts in general, based on the transient intermediacy of radical-derived trichloromethyl benzenediazoate (PhNNOCCl₃) which decomposes into the diazonium chloride and phosgene, which in turn reacts with unchanged diazonium acetate to give the diazonium chloride, acetic anhydride, and carbon dioxide.