DescriptionThis dissertation focuses on the study of benzoin condensation and the Setter reaction. Both experimental (mass spectrometry) and computational (Gaussian 09) methods were utilized. A sulfonate charged tag thiazolium catalyst was synthesized and used to track the reaction process of benzoin consendation. Key intermediates corresponding to Breslow mechanism were isolated. Collision induced dissociation of the intermediates yielded fragments. The fragmention analysis was used to support structural assignments. In order to confirm the stablity of isomers, calculations were also conducted. Our results are consistent with a Breslow mechanism as opposed to dimer mechanism. The acidity of two families of triazolium catalysts (morpholine-fused and pyrrolidinefused triazolium) were studied in the gas phase. The experimental results were consistent with the calculations except for a pair of trans and cis fluorinated triazolium catalysts. Kinetic acidity issues were proposed to explain the discrepancies between calculations and experiments. This hypothesis was supported by conducting electrostatic potential surface calculation. The possible hypothesis of a bizarre reactivity and selectivity difference for trans and cis fluorinated catalysts were also proposed.