Reactions of Dehydro-N-pyridinium with Small Unsaturated Hydrocarbons

Small nitrogen containing heteroaromatics are fundamental building blocks for many biological molecules, including the DNA nucleotides. Pyridine, as a prototypical Nheteroaromatic, has been implicated in the chemical evolution of many extraterrestrial environments, including the atmosphere of Titan. This thesis describes reactions of the three dehydro-N-pyridinium radical cation isomers with a set of small, unsaturated hydrocarbons: propene, acetylene, ethene and propyne. These reactions were chosen due to their possible involvement in molecular-weight growth processes, and in the synthesis of complex organics in space. Mass spectrometric techniques are used to acquire product mass spectra, measure product branching ratios and calculate second-order rate coefficients for reactions of 2-dehydro-N-pyridinium, 3-dehydro-N-pyridinium and 4- dehydro-N-pyridinium with each neutral hydrocarbon co-reactant. Quantum chemical calculations are used to validate experimental results and elucidate possible reaction mechanisms for the propene and acetylene reaction systems. Potential energy schemes are presented, together with a quantum state counting kinetic modelling analysis for propene reactions.