Ionic Organic Reactions and Their Intermediates

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This project addresses the synthesis and study of novel carbocations and onium ions. Protonated highly-substituted benzenium dications such as m-xylene, mesitylene and hexamethylbenzene will be generated in superacids under stable ion conditions. The elusive bis-, tris- and tetradiazomethane di, tri- and tetracation, respectively, will be modeled with ab initio/GIAO-MP2 calculations and prepared and spectrally characterized in superacid solution. A number of interesting trifluoromethylsubstituted allyl cations and polyallyl cations and several silylated onium ions, including silylated urea, guanidinium ion, formamide and acetamide ions, will also be examined. Superelectrophilic activation of N,N-dimethylmethyleniminium ion, CH2=N(CH3)2+ and the isomeric isopropyleniminium ion, (CH3)2C=NH2+ will be investigated by hydrogen/deuterium exchange experiments. Sulfur and phosphorous analogs of dialkyl ether/poly(hydrogen fluoride) i.e dialkyl thioether/poly(hydrogen fluoride) and trialkyl phosphine/poly(hydrogen fluoride) complexes will be prepared and studied as new ionic liquids.With this award, the Organic and Macromolecular Chemistry Program is supporting the research of Dr. George A. Olah of the Department of Chemistry at the University of Southern California. Combining experimental structural and mechanistic studies with theoretical analyses, Professor Olah and his students are elucidating fundamental steps in chemical processes. Their studies are focused on the generation, structure, and reaction chemistry of reactive intermediates bearing one or more positive charges. Such novel intermediates have been implicated in numerous processes of laboratory and commercial significance. These studies are providing important insights into the design of selective organic reactions and into the phenomena at play in large-scale petrochemical processes such as catalytic cracking and alkylation reactions.