Ionisation rates of β-substituted nitroethanes

Abstract

Ionisation rates of a series of aliphatic nitro-compounds, YCH₂·CH₂·NO₂, have been measured in aqueous sodium hydroxide and in ethanolic sodium ethoxide. Rectilinear σ*ρ* plots for substituents Me, H, Ph, OH, and EtO with ρ*_H2O= 2·07 and ρ*_EtOH= 1·88 have been obtained; the β-diphenyl compound, Ph₂CH·CH₂·NO₂ ionises more slowly than the monophenyl compound notwithstanding the expected rate-accelerative effect of the second phenyl group.

Solvent and salt effects are discussed in connection with transition states for ionisation.