International journal of mass spectrometry vol:217 issue:1-3 pages:45-54
date:Univ Louvain, Dept Chem, B-3001 Louvain, Belgium; Univ Mons, Organ Chem Lab, B-7000 Mons, Belgium; Ho Chi Minh City Univ Technol, Fac Chem Engn, Grp Computat Chem, Thanh Pho Ho Chi Minh, Vietnam
A multi-sector tandem mass spectrometer fitted with a radiofrequency (rf)-only quadrupole collision cell (Qcell) has allowed fast and unambiguous identification of dehydroanilinium ions, the distonic isomers of ionized aniline. These ions were prepared by collisional deiodonation of protonated iodoanilines previously generated by chemical ionization (CI) or even better by liquid secondary ion mass spectrometry (LSIMS) conditions. Ab initio quantum chemical calculations were also used to probe the protonation of aniline and halogeno-anilines, X-C6H4-NH2 (X = F, Cl, Br and 1) and the relative stabilities of ionized aniline and its distonic radical cation isomers. Proton affinities (PAs) of anilines at nitrogen and carbon sites were found rather dependent on the nature and the position of the substituents. (C) 2002 Elsevier Science B.V. All rights reserved.