22499-63-4Relevant articles and documents
Chemical ionization using CF3+: Efficient detection of small alkanes and fluorocarbons
Dehon, Christophe,Lemaire, Jo?l,Heninger, Michel,Chaput, Aurélie,Mestdagh, Hélène
, p. 113 - 119 (2011)
The trifluoromethyl ion CF3+ is evaluated as a chemical ionization (CI) precursor in a compact Fourier Transform Ion Cyclotron Resonance (FTICR) mass spectrometer. It reacts with alkanes by hydride abstraction allowing characterization and quantification of alkanes up to C4 and cyclic. With larger alkanes fragmentation occurs. Fluorocarbons react by fluoride abstraction. Rate coefficients have been measured for reaction with alkanes, fluoroalkanes, chlorofluoroalkanes as well as several common VOCs. Use of CF3+ for trace analysis in air has been tested on an air sample containing traces of acetone, toluene, benzene and cyclohexane. The results are consistent with those obtained with H3O+ precursor and allow additional cyclohexane quantification.
Dissociative proton transfer reactions of H3+, N2H+, and H3O+ with acyclic, cyclic, and aromatic hydrocarbons and nitrogen compounds, and astrochemical implications
Milligan, Daniel B.,Wilson, Paul F.,Freeman, Colin G.,Meot-Ner (Mautner), Michael,McEwan, Murray J.
, p. 9745 - 9755 (2007/10/03)
A flowing afterglow-selected ion flow drift tube has been used to measure the rate coefficients and product ion distributions for reactions of H3O+, N2H+, and H3+ with a series of 16 alkanes, alkenes, alkynes, and aromatic hydrocarbons as well as acrylonitrile, pyrrole, and pyridine. Exothermic proton transfer generally occurs close to the collision rate. The reactions of H3O+ are mostly nondissociative and those of H3+ are mostly dissociative, but many reactions, especially those of N2H+, have both dissociative and nondissociative channels. The dissociative channels result mostly in H2 and/or CH4 loss in the small hydrocarbons and in toluene, loss of C2H2 from acrylonitrile, and loss of HCN from pyrrole. Only nondissociative proton transfer is observed with benzene, pyridine, and larger aromatics. Drift tube studies of N2H+ reactions with propene and propyne showed that increased energy in the reactant ion enhances fragmentation. Some D3+ reactions were also investigated and the results suggest that reactions of H3+ with unsaturated hydrocarbons B proceed through proton transfer that forms excited (BH+)* intermediates. Pressure effects suggest that a fraction of the (BH+)* intermediates decomposes too rapidly to allow collisional stabilization in the flow tube (t -8 s). The other low-energy (BH+)* intermediates are formed by the removal of up to 40% of the reaction exothermicity as translational energy, and these intermediates result in stable BH+ products. The results suggest that, in hydrogen-dominated planetary and interstellar environments, the reactions of H3+ can convert C2-C6 hydrocarbons to smaller and less saturated molecules, but polycyclic aromatics are stable against decomposition by this mechanism. The dissociative reactions of H3+ can therefore favor the accumulation of small unsaturated hydrocarbons and aromatics in astrochemical environments.
Elemental Compositions from Daughter Ion Spectra of m1+ and 1 + 1>+: Some Applications of the Method
Bozorgzadeh, M. H.,Lapp, R. L.,Gross, M. L.
, p. 712 - 718 (2007/10/02)
The elemental compositions of ions can be determined in tandem mass spectrometry by comparing the daughter ion spectra of the m1+ and 1 + 1>+ ions.The method is demonstrated for mass-analyzed ion kinetic energy spectra but is applicable to all types of daughter ion spectra, including complex collisionally activated dissociation spectra.In this work, the method is applied to compounds that produce daughter ions of known elemental compositions, and the errors and limitations are evaluated.Following that test, the procedure is applied to a compound that may produce daughters of more than one possible elemental composition.The method is sometimes useful even if the formula of the parent is not known; that is, the formulae of unknown parent and daughter ions may be found.Locating a specific atom in an isotopically labeled molecule is another capability of the method.The basic equation of the method was generalized and incorporated into a computer program for performing the calculations.
