Radical abstraction of iodine from aromatic iodides

Abstract

Decompositions of the isomeric o-, m-, and p-iodo-N-nitrosoacetanilides in benzene give o-, m- and p-di-iodo-benzenes as well as the expected 2-, 3-, and 4-iodobiphenyls, respectively. Decompositions of aroyl peroxides [(ArCO₂)₂] in iodobenzene, and even in iodobenzene diluted with benzene, give good yields of the aryl iodide (Arl) together with isomeric mixtures of 2-, 3-, and 4-iodobiphenyls formed by homolytic phenylation of iodobenzene. These results point to very rapid radical abstraction of iodine by the aryl radical from aryl iodides. The corresponding reaction with aryl bromides does not take place. The kinetics of the decomposition of dibenzoyl peroxide in iodobenzene, measured, for the first time, by a new route involving reduction of unchanged peroxide by triethyl phosphite, are similar to those of the decomposition in bromobenzene.

Di-p-nitrobenzoyl peroxide in iodobenzene gives (di-p-nitrobenzoyloxyiodo)benzene as an additional product.