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

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Eur. J. Mass Spectrom. 5, 259 - 265 (1999)

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

Marta Herreros, Jean-Fran‡ois Gal,_* Pierre-Charles Maria and Michèle Decouzon
Groupe FT-ICR, GRECFO-Chimie Physique Organique, Université de Nice-Sophia, Antipolis, F-06108 Nice Cedex 2, France. E-mail: .

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.

Keywords: ab initio calculations, amides, basicity, lithium, mass spectrometry, FT-ICR mass spectrometry.

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