Ion [C5H5O]+ formation in the electron-impact mass spectra of 4-substituted N-(2-furylmethyl)anilines.: Relative abundance prediction ability of the DFT calculations

Six 4-substituted N-(2-furylmethyl)anilines have been studied by electron ionization (EI) mass spectrometry. The heterolytic dissociation of the C-N bond of the molecular ions was proposed as the route to the main fragment ion in the mass spectra, [C5H5O](+) (m/z = 81). Reaction energies for this process were calculated at UB3LYP/6-31G(d,p) and UHF/6-31G(d,p) levels of theory. DFT calculations produced reaction energy values that showed very good correlation with the logarithms of the peak intensity ratios for the [C5H5O](+) and [M](+) center dot ions. Linear regression yielded an equation, which could be used to calculate the intensity ratio [C5H5O](+)/[M](+) center dot, with an error < 10%, from both the analogous ratio in a known mass spectrum and theoretical reaction energies. (c) 2006 Elsevier B.V. All rights reserved.