Heavy-Atom Kinetic Isotope Effects in the Acid-Catalyzed Rearrangement of N-2-Naphtyl-N'-phenylhydrazine. Rearrangement Is Shown To Be a Concerted Process

Article abstract of DOI:10.1021/ja00309a041

Heavy-atom kinetic isotope effects (KIE) have been measured in the acid-catalyzed rearrangement of N-2-naphthyl-N'-phenylhydrazine (1) into 1-(o-aminophenyl)-2-naphthylamine (2).A combination of whole-molecule-ion and isotope ratio mass spectrometry and scintillation counting has given KIE for 15N, 13C, and 14C.Use of <15N,15N'>1 and whole-molecule-ion mass spectrometry gave a KIE of 1.0434 (for two 15N atoms).Use of <1-13C>1 and isotope-ratio mass spectrometry gave a KIE of 1.0196 for one naturally abundant 15N atom and 1.0042 for one 13C atom.Use of <2'-14C>1 gave a KIE of 1.0142 for one 14C atom.The results show that this rearrangement is a concerted process, namely a <3,3>-sigmatropic shift.The transition state, furthermore, appears to be unsymmtetrical.That is, the extents of N-N bond breaking and C-C bond forming appear to be unequal.