Gas-phase basicity of simple amides toward proton and lithium cation: an experimental and theoretical study

Abstract

The gas-phase lithium cation basicities (LCBs) of the six amides RC(O)NRR' (R, R' = H or Me) were reexamined by means of Fourier transform ion cyclotron resonance mass spectrometry and using the kinetic method. LCBs for HCONH2, MeCONH2 and MeCONHMe were reevaluated. The new set of experimental data was found to be consistent with the expected methyl-substitution effects. For a series of compounds including the six amides and H2CO, MeCHO and Me2CO, density functional theory calculations of LCBs and gas-phase proton basicities (GBs) at the B3LYP level reproduce satisfactorily the trend of substitution effects.