Revision of the α H2 value for N,N-dialkylhydroxylamines based on kinetic and spectroscopic measurements

Abstract

Kinetic solvent effects on hydrogen-atom abstraction from N,N-diethylhydroxylamine and N,N-dibenzylhydroxylamine by the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH˙) indicated that these compounds are much weaker hydrogen-bond donors than implied by the currently accepted α^H₂ value of 0.453. Lower α^H₂ values were also obtained by monitoring 1 ∶ 1 complex formation with two strong hydrogen-bond acceptors, HMPA and DMSO, in tetrachloromethane using IR spectroscopy. It is concluded that the α^H₂ value for sterically non-hindered N,N-dialkylhydroxylamines should be revised downward to 0.29.