title: Gas-phase positive ion chemistry of 1-bromo-1-chloro-2,2,2-trifluoroethane (halothane) upon electron ionization within an ion trap mass spectrometer.
abstract: The positive ion chemistry occurring within an ion trap mass spectrometer upon electron ionization of 1-bromo-1-chloro-2,2,2-trifluoroethane, the important anaesthetic halothane, has been mapped by means of collision-induced decomposition and ion/molecule self-reaction experiments. Ionized halothane (M+*) reacts with neutral halothane to form the ionized olefin [ClBrC=CF2]+*. via HF elimination. Among the ionic fragments, [M-Br]+ and [M-F]+ react with halothane via chloride abstraction while [M-Cl]+ is unreactive under the same experimental conditions. Substituted methyl cations CHFX+ and CF2X+ (X = F, Cl, Br) undergo halide transfer processes, their reactivity being highest for X = F. Ionized carbenes CXY+ (X,Y = F,F; H,Br; H,Cl; H,F) react with halothane to form CClXY+ and CBrXY+, whereas CF+ inserts into the C-Cl bond to form CF3+ and CClF2+. Finally, Br+ and Cl+ react with halothane by charge transfer. Collision-induced dissociation experiments disclosed interesting rearrangements involved in the dissociations of +CHX-CF3 ions (X = Br, Cl), which undergo fluorine migration and elimination of CF2, as already observed for +CCl2-CF3 in a previous investigation.
authors.affiliation: INTM del CNR--Sezione di Padova, Dipartimento di Scienze Chimiche, Università di Padova, Via Marzolo 1, 35131 Padova, Italy.
authors.forename: Ester
authors.initials: E
authors.lastname: Marotta
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Scorrano
authors.forename: Cristina
authors.initials: C
authors.lastname: Paradisi