Turbulent Ion Flow Tube Study of the Cluster-Mediated Reactions of SF6- with H2O, CH3OH, and C2H5OH from 50 to 500 Torr

Reactions of SF 6 - with H 2 O, CH 3 OH, and C 2 H 5 OH were studied at 298 K from 50 to 500 Torr in a newly constructed turbulent ion flow tube (TIFT). These reactions were found to be cluster-mediated reactions, where the reactants are in equilibrium with a stable association complex and then products are formed via a bimolecular reaction of the complex with a second neutral reactant. By use of known equilibrium constants, rate constants were derived for the reaction of the complex with the second solvent molecule. The rate constants for these reactions, which are essentially pressure-independent, are 3.2 × 10 -14 cm 3 s -1, 1.8 × 10 -13 cm 3 s -1, and 2.2 × 10 -13 cm 3 s -1 for H 2 O, CH 3 OH, and C 2 H 5 OH, respectively. Primary product ions for the H 2 O reaction include SOF 4 - and F - (HF) 2, and primary products for the CH 3 OH and C 2 H 5 OH reactions include F - (HF)(ROH) and F - (HF) 2 . The observed ions are frequently solvated. The product distributions for the alcohol reactions show pressure dependencies from 50 to 500 Torr. These results have implications for the modeling of low-temperature corona or glow-type discharges, as well as for the use of SF 6 - as a chemical ionization mass spectrometry agent in humid environments.