title: An aniline dication-like transition state in the Bamberger rearrangement.
abstract: A Bamberger rearrangement of N-phenylhydroxylamine, Ph-N(OH)H, to p-aminophenol was investigated by DFT calculations for the first time. The nitrenium ion, C6H5-NH(+), suggested and seemingly established as an intermediate was calculated to be absent owing to the high nucleophilicity of the water cluster around it. First, a reaction of the monoprotonated system, Ph-N(OH)H + H3O(+)(H2O) n (n = 4 and 14) was examined. However, the rate-determining transition states involving proton transfers were calculated to have much larger activation energies than the experimental one. Second, a reaction of the diprotonated system, Ph-N(OH)H + (H3O(+))2(H2O)13, was traced. An activation energy similar to the experimental one was obtained. A new mechanism of the rearrangement including the aniline dication-like transition state was proposed.
authors.affiliation: Fukui Institute for Fundamental Chemistry, Kyoto University, Takano-Nishihiraki-cho 34-4, Sakyo-ku, Kyoto 606-8103, JAPAN.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Yamabe
authors.forename: Guixiang
authors.initials: G
authors.lastname: Zeng
authors.forename: Wei
authors.initials: W
authors.lastname: Guan
authors.forename: Shigeyoshi
authors.initials: S
authors.lastname: Sakaki
keywords: Bamberger rearrangement; DFT calculations; N-phenylhydroxylamine; proton transfer; reactive intermediates; transition states