57178-38-8Relevant articles and documents
Gas-phase reactions of oxide and superoxide anions with CF4, CF3Cl, CF3Br, CF3I, and C2F4 at 298 and 500 K
Morris, Robert A.
, p. 2372 - 2381 (2007/10/02)
Rate constants and product branching fractions have been measured for the gas-phase reactions of oxide (O-) and superoxide (O2-) anions with the halocarbons CF4, CF3Cl, CF3Br, CF3I, and C2F4 using a variable temperature-selected ion flow tube (VT-SIFT) instrument operated at 298 and 500 K.The reactions of O- with CF3X (X = Cl, Br, I) are fast and produce F-, XF-, and XO- for all X.For CF3Cl and CF3Br, X- is also formed.For CF3I, CF3- and IOF- are minor products.O- reacts rapidly with C2F4 producing F- as the major ionic product, along with contributions from reactive detachment and minor formation of FCO-, CF3-, and C2F3O-.The reaction of O2- with CF3Cl is slow, and both clustering and X- formation were observed.For CF3Br and CF3I, the reactions with O2- are fast, and nondissociative charge transfer was observed in addition to X- formation.O2- reacts rapidly with C2F4 by reactive detachment, in addition to producing F- as the major ionic product with smaller amounts of F2-, FCO-, FCO2-, CF3O-, and C2F4O-.O- and O2- were both found to be unreactive with CF4 at 298 and 500 K.The efficiencies of the reactions of both O- and O2- with CF3X are greater for the heavier halides at both 298 and 500 K.The rate constants for the reactions of O2- with CF3X appear to correlate both with the rates of thermal electron attachment to CF3X and with the electron affinities of CF3X, indicating that the O2- + CF3X reaction mechanism may involve initial electron transfer followed by dissociation.Thus the negative electron affinity of CF3Cl may explain the very slow rate for reaction with O2- despite the available exothermic pathways.
