A study of essentially free carbocations derived via diazonium and oxo diazonium ions in the liquid phase

Nitrogen- and nitrous oxide-separated ion pairs containing Li-substituted b enzyl cations and carboxylate or tosylate anions were prepared by thermolys is of N-nitroso- and N-nitroamides, acidification of phenyldiazomethane, an d nitrosation of N-benzyl-O-benzoylhydroxylamine. The cations were generate d in benzene/toluene and benzene/anisole mixtures and were found to partiti on between the counterion and the solvent and between the aromatic cosolven t and benzene. A familial relationship among the methods was observed. As t he cation became more reactive, the yield of solvent-derived products (SDPs ) rose and the ratio of rate constants for its reaction with toluene versus benzene, k(T)/k(B), fell. The yield of SDP also rose as the temperature wa s decreased and as N-2 was replaced by N2O; however, k(T)/k(B) remained unc hanged. Inert diluents had no effect on k(T)/k(B) but decreased hydrocarbon yield by 40% on 2-fold dilution. In the presence of reactive diluents that are converted into secondary alkylating agents, both the % hydrodarbon and k(T)/k(B) rose. These results are interpreted in terms of the intermediacy of inert-molecule-separated ion pairs (IMSIPs) in deamination. The cation reacted with benzoates and tosylates not only at the oxygens but also at th e ipso carbon; subsequent decarboxylation and desulfonylation, respectively , led to diphenylmethanes. The ester/SDP ratio is introduced as a new measu re of carbocation reactivity.