Relation to Triarylmethyl

When one of the aromatic groups of the triarylmethyl free radical is replaced by an alkyl group, a decrease in stability due to a loss of resonance stabilization is to be expected. The paramagnetism and reactions associated with these less stable radicals will therefore appear only when the ethane is heated well above room temperature, the dissociation being endothermic. The rate of formation, but not the equilibrium constant, is experimentally accessible for these radicals since the radical once formed is subject to rearrangement, cleavage, and disproportionation reactions  

The rate of dissociation has been measured by oxygen uptake in the presence of an inhibitor of chain reactions as in the case of hexaaryl-ethanes. Since the uptake of oxygen obeys the same kinetic law, it is a reasonable extrapolation to suppose that here too the rate-determining step is a dissociation into radicals. When one of the phenyl groups in triphenylmethyl is replaced by a cyclohexyl group, the rate of dissociation of the ethane is reduced by a factor of 170.38 Some dissociation rate parameters are given in Tables III A and B. 

When solutions of ethanes with four aryl groups and two bulky 

The same thing happens when alkyl halides are treated with silver in the presence of oxygen.41 The reaction with silver in the absence of oxygen is of course one of the methods used to prepare the stable triarylmethyl free radicals. 

When the nitrile IV is heated it develops color reversibly at 100° and above. Bases, however, cause the formation of a product analogous 

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