A comparative study of the reactivity of didehydropyridiniums toward cyclohexane and decalin in the gas-phase by using Fourier-transform ion cyclotron resonance mass spectrometry
The goal of this thesis was to compare the ability of two different neutral reagents to react with specific organic singlet biradicals via a radical reaction, hydrogen atom transfer. The reactions were studied in a mass spectrometer by using the distonic ion approach, i.e., the biradicals were charged. The two neutral reagents chosen are cyclohexane and decalin. ^ Each biradical was generated in the dual-cell of a Fourier-transform ion cyclotron resonance mass spectrometer (FT-ICR) and allowed to react with cyclohexane and decalin, and the efficiency of each reaction was measured. Three types of products were formed in reactions with cyclohexane and decalin. The main product was formed by abstraction of two hydrogen atoms. In addition, hydride abstraction and addition/elimination products, such as those formed by addition-H2O (addition and loss of water) and alkyl abstraction, were observed. All these products are likely formed in radical reactions. Though similar products were formed for the two reagents, the reaction efficiencies were found to be very different. Cyclohexane is the slower reacting reagent, with efficiencies ranging from 0.1 to 63%, while reactions with decalin occurred at efficiencies ranging from 2 to 72%. Unfortunately, decalin is difficult to introduce into the FT-ICR at a constant pressure. This difficulty in controlling the pressure of decalin limits its usage as the primary reagent for testing radical reactivity of singlet biradicals.^
Hilkka I. Kenttamaa, Purdue University.