Proton affinities and heats of formation of the imines CH2NH, CH2NMe and PhCHNH
- 1 January 1990
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 2
- No. 11,p. 1825-1828
- https://doi.org/10.1039/p29900001825
Abstract
The proton affinities of the imines CH2 NH, CH2 NMe and PhCHNH have been determined by Fourier transform ion cyclotron resonance (FT-ICR) mass Spectrometry to be 854 ± 8 kJ mol–1, 880 ± 8 kJ mol–1 and 908 ± 8 kJ mol–1, respectively. These results lead, in conjunction with known ΔHf 0 values for the protonated species, to ΔHf 0(CH2 NH)= 69 ± 8 kJ mol–1, which is significantly lower than previously reported in the literature, and to ΔHf 0(CH2 NMe)= 44 ± 8 kJ mol–1. The proton affinities of the small imines are between the values for the corresponding amines and nitriles. The decrease in proton affinity with the change in hybridization of the nitrogen atom from sp3 to sp2 to sp is discussed together with the increase in proton affinity upon introduction of a methyl group on either the carbon atom or the nitrogen atom in CH2 NH.This publication has 34 references indexed in Scilit:
- The gas-phase acidities of the alkanesJournal of the American Chemical Society, 1989
- Quantum chemical study of the site of protonation in conjugated schiff basesJournal of Molecular Structure: THEOCHEM, 1987
- Stable covalent and hydrogen-bonded acid-base association. Ab initio study of [CH2O · H · NH3]+ and [CH2NH · H · OH2]+ complexesInternational Journal of Mass Spectrometry and Ion Processes, 1987
- The electronic structure of CH2NH, CH2NLi and CH2NBeHJournal of Molecular Structure: THEOCHEM, 1986
- Geometry, basis set, and correlation energy dependence of computed protonation energies of imino basesJournal of Computational Chemistry, 1984
- Theoretical studies of the gas-phase proton affinities of molecules containing phosphorus-carbon multiple bondsThe Journal of Physical Chemistry, 1984
- Molecular orbital study of some protonated basesThe Journal of Physical Chemistry, 1982
- Electronic structure of vinylamine. Proton affinity and conformational analysisJournal of the American Chemical Society, 1981
- Scale of acidities in the gas phase from methanol to phenolJournal of the American Chemical Society, 1979
- Gas phase basicities and relative proton affinities of compounds between water and ammonia from pulsed ion cyclotron resonance thermal equilibriums measurementsJournal of the American Chemical Society, 1977