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Low Pressure Gas‐phase Reactions of the Atomic Oxygen Radical Anion with Halomethanes Studied Using Fourier Transform Ion Cyclotron Resonance
Author(s) -
Staneke P. O.,
Kauw J.,
Born M.,
Ingemann S.,
Nibbering N. M. M.
Publication year - 1997
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/(sici)1097-0231(19970115)11:1<124::aid-rcm793>3.0.co;2-w
Subject(s) - chemistry , fourier transform ion cyclotron resonance , halogen , ion cyclotron resonance , bromine , ion , chlorine , atom (system on chip) , photochemistry , organic chemistry , cyclotron , alkyl , computer science , embedded system
The gas‐phase reactions of the O −• radical anion with the halomethanes CH 3 X, CH 2 X 2 , CHX 3 , CX 4 , CF 3 X, CF 2 X 2 , CFX 3 (X = Br and Cl) and CXClBr 2 (X = Cl and F) have been examined at a low pressure (10 −5 –10 −4 Pa) with use of Fourier transform ion cyclotron resonance (FTICR) mass spectrometry. The overall reactions proceed essentially with the collision rate and lead to a variety of product ions dependent on the number and nature of the halogen atoms present in the substrate. For CH 3 CI and CH 3 Br, the dominant pathways are H • abstraction, H 2 +• abstraction and nucleophilic substitution. With CH 2 CI 2 , proton transfer is an additional major pathway and in the reaction with CH 2 Br 2 attack on a halogen atom with formation of BrO − ions also occurs. In the reactions with CHCl 3 and CHBr 3 , proton transfer competes with attack on a halogen atom, whereas initial attack on a halogen atom dominates in the reactions of O −• with the CCl 4 and CBr 4 methanes. Attack on the carbon atom is the main process if CF 3 Cl is the substrate and results in F − , Cl − as well as FCl −• ions. For CF 3 Br, however, attack on the bromine atom with formation of BrO − ions dominates over the reaction at the carbon atom. In the reactions with CF 2 Cl 2 , CFCl 3 , CF 2 Br 2 , as well as the CCl 2 Br 2 and CFClBr 2 methanes, most product ions are formed by competing attack on a chlorine and bromine atom. For some of the halomethanes, the present findings are compared with reported results obtained with use of the high pressure (≡70 PA) flowing afterglow and selected ion flow tube methods. © 1997 John Wiley & Sons, Ltd.