Reduction of nitro- and nitroso-compounds by tervalent phosphorus reagents. Part III. Kinetic study of the triethyl phosphite reduction of 2-nitrosobiphenyl to carbazole

Abstract

The triethyl phosphite reduction of 2-nitrosobiphenyl to carbazole in triethyl phosphate as solvent is of the first order in both reactants; the activation energy is 11·56 kcal. mole^–1, and the entropy of activation ΔS*, at 25° is –29 e.u. The similarity of these data to those obtained for the Menshutkin and Arbusov reactions indicates that the rate-determining step involves the formation of an intermediate complex involving both reagents, possibly (EtO)₃P⁺–O–^–NAr, which then decomposes rapidly to give products. The possible intermediacy of a nitrene is neither proved or disproved.