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Collision‐induced dissociation and charge‐reversal processes of isomeric C 6 H 4 X − (X = F, Cl and Br) anions
Author(s) -
Tomperi Päivi H.,
Matimba Henri E. K,
Ingemann Steen,
Nibbering Nico M. M.
Publication year - 1993
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.1290070814
Subject(s) - chemistry , halogen , bromobenzene , dissociation (chemistry) , ion , fourier transform ion cyclotron resonance , deuterium , fluorobenzene , mass spectrometry , analytical chemistry (journal) , photochemistry , benzene , atomic physics , alkyl , physics , organic chemistry , chromatography , catalysis , biochemistry
The NH 2 −ion reacts with fluoro‐ and chlorobenzene in the cell of a Fourier‐transform ion cyclotron resonance instrument only by proton abstraction, whereas the reaction with bromobenzene also yields Br − ions. The deprotonation of these halogen‐substituted benzenes occurs the 2‐, 3‐ or 4‐positions as revealed by deuterium labelling in combination with high kinetic energy (8keV) collision‐induced dissociation (CID) experiments performed with a double‐focusing quadrupole hybrid mass spectrometer. The 2‐fluoro‐ and 3‐ fluorophenyl anions eliminate HF following collision with an oxygen molecule. By contrast, the collisions between 4‐fluorophenyl anions and O 2 do not yield detectable amounts of negatively charged fragment ions owing to the exclusive occurrence of electrom detachment. Electron detachment is also the only process observed in the 8 keV CID experiments with chlorophenyl anions and 3‐ and 4‐bromophenyl anions, whereas the ion formed by proton abstraction from the 2‐position in bromobenzene dissociates to Br − and 1,2‐dehydrobenzene. The 8 keV collision‐induced charge‐reversal spectra of the anions formed by proton abstraction from the 2‐, 3‐ or 4‐positions in a given halogen‐substituted benzene are virtually identical, indicating that this method does not provide insight into the position of the charge with respect to the halogen atom in the substituted phenyl anions.