Formation of Unstable Radicals in the Liquid Phase

The formation of radicals in the liquid phase is of greater interest to organic chemists than is the corresponding gas phase reaction, because it is not limited to substances of low molecular weight. It takes 

For example, in the decomposition of phenylazotriphenylmethane in benzene, triphenylmethyl peroxide is formed if oxygen is present, indicating a radical reaction. The unstable phenyl radical does not persist long enough to dimerize but reacts instead with the solvent. 

when the radical generated is -chlorophenyl, no dichlorobi-phenyl is formed but only -chlorobiphenyl.55 

The decomposition of aromatic diazonium salts in neutral or alkaline solution generates radicals that attack supernatant benzene.64 

An intramolecular transfer of hydrogen as well as ring closure occurs with diazonium salts containing a suitably located second aromatic ring.87 The amount of ring closure by radicals, however, is very much less than the amount that occurs in the corresponding polar reaction. 

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