This grant in Organic and Macromolecular Chemistry is made under the auspices of the Research Opportunities for Women Program. The award provides support for research by Dr. Hilkka Kenttamaa, Purdue University, which is aimed at characterizing the chemical and physical properties of molecular fragments in the gas phase. Quadrupole mass spectrometry will be employed to measure reactivity of both charged (cationic) and neutral (radical) fragments of organic molecules. Understanding the reactivity of molecular fragments in the gas phase is important both for understanding chemical events which occur in the upper atmosphere, and for understanding the influence of solvation upon the many chemical reactions which occur in solution. Two different types of quadrupole mass spectrometers will be employed: an ion trap equipped with pulsed valves, and a triple quadrupole tandem mass spectrometer. The various capabilities of the two techniques will be utilized in studies on three different areas. (i) Mechanisms and potential energy surfaces of acid-catalyzed reactions of epoxides in the absence of solvents will be studied. In addition, experiments are planned which will yield thermochemical data for neutral epoxides, protonated epoxides and their isomeric forms. (ii) Relative stabilities and intrinsic chemical reactivity of coordinately unsaturated borocations are a topic of interest. The experiments employed will allow heats of formation to be determined for borenium ions and various other boron-containing species, including derivatives of neutral metaboric and metaboronic acids. (iii) Studies on bimolecular gas-phase chemistry of ionized ylides and ionized zwitterions will provide information concerning the thermochemistry and reactivity of these interesting ions as well as their neutral gas-phase radical and diradical analogs.