ION/MOLECULE REACTIONS STUDIED WITH THE FLOWING AFTERGLOW AND THEORETICAL METHODOLOGY

Initial interest in ion/molecule chemistry was because of its importance in atmospheric chemistry, but researchers have moved to investigating other interests involving organic reaction mechanisms. The study of ion/molecule reactions has flourished with the invention of instruments, such as the flowing afterglow instrument, and the advances in computational chemistry. The hydronium ion has been utilized as a reagent ion in ion/molecule chemistry for the detection of volatile organic compounds (VOCs). A limitation to the utility of the hydronium ion is that it is susceptible to clustering reactions with water. The propensity to cluster can be eliminated by replacing the hydrogens on the hydronium ion with trimethylsilyl groups to form the tris-trimethylsilyloxonium ion, (TMS)3O+. This strategy takes advantage of the trimethylsilyl cation's proclivity to react as if it were a proton. Hexamethyldisiloxane was allowed to react with TMS+, (TMS)2Cl+, TMSOH2+, and TMSC6H6+ in an attempt to form (TMS)3O+. However, every attempt to create the novel (TMS)3O+ via a gas phase approach was unsuccessful. The available data suggests that the target ion may be formed, but is so reactive under the experimental conditions that it reacts away prior to detection. An investigation of the formation and reactions of the bis-trimethylsilylmethyloxonium ion ((TMS)2OCH3+) was conducted to gain further understanding of the chemistry of the formation and reactivity of oxonium ions. After successful formation of the bis-trimethylsilylmethyloxonium ion, six neutrals (water, dimethylsulfide, acetonitrile, ethyl acetate, triethylamine, and acetone) were allowed to react one at a time with it. Trimethylsilyl transfer was the primary reaction pathway, which bodes well for our goal of creating a novel reagent ion.The oxygen radical anion, O·-, has been studied by others with respect to atmospheric chemistry and has been utilized for chemical ionization reactions. To better understand its reactivity, a theoretical study of the reaction of the O·- with methanol has been analyzed. Reaction schemes and potential energy diagrams for observable products and for all possible products were created. The potential energy surface computed during this study suggests that at 298 K the expected product distribution is proton transfer