Mechanisms of nucleophilic attack at carbon-nitrogen double bonds: Reactions of benzohydrazonoyl halides with secondary amines in benzene

The reactions of a series of substituted benzohydrazonoyl halides with cyclic secondary amines in benzene as solvent are investigated. The rate equations for these reactions were complex and the derived rate data are reported. The element effect data showed that the fluoro compounds only reacted when a second amine molecule was available to assist the reaction, whereas the chloro and bromo compounds reacted by reactions which were both first order and second order in amine (k ''(Br): k ''(Cl) = 9.5:1 and k'''(Br):k'''(Cl):k'''(F) = 4.7:1:0.65). The mechanism of these reactions is discussed.