| This dissertation describes a number of hydrocarbon transformations and functionalizations that are catalyzed by superacids. Brönsted superacids, up to a trillion times stronger than sulfuric acid, have found extensive use in acid-catalyzed industrial processes and chemical synthesis.; Chapter 1 describes the dissertation's overall goals as well as a brief historical background of electrophilic hydrocarbon chemistry. Chapter 2 gives a description of three fundamental concepts used in superacid catalyzed hydrocarbon reactions: superacidity, σ-basicity, and superelectrophilic activation. A general overview of the different Brösted superacid systems are given with emphasis on their physical properties and Hammett acidities.; Chapter 3 explores the protolytic activation of carbon monoxide into the highly reactive protosolvated formyl cation which has been found to insert into isoalkanes producing branched ketones and aldehydes of generally high octane number. The currently used major oxygenate in reformulated gasoline, methyl tert-butyl ether (MTBE), is being phased out due to environmental considerations and new safe oxygenates are needed. After a brief account of why oxygenates are needed in reformulated gasoline and of electrophific formylations, the chapter discusses mechanisms for the ketones and aldehydes obtained and explores the reaction with various alkanes.; Chapter 4 explores liquid and supercritical CO2as a possible solvent for the industrially important isobutane/isobutylene alkylation used to produce highly branched isoalkanes in reformulated gasoline. In the past 10 years supercritical fluids have been studied as an alternative to conventional solvents in a number of reactions and often produce interesting results. The current trend in research of supercritical fluids is due to a number of interesting properties they possess. This chapter marks the first time liquid and supercritical CO2 have been used as a solvent for electrophilic reactions using Brönsted acids, including the superacids trifluoromethanesulfonic acid and hydrofluoric acid.; Chapter 5 describes a simple, direct preparation of diaryl sulfoxides starting from readily available thionyl chloride, arenes, and the superacid trifluoromethanesulfortic acid. The reaction is further characterized by high yields and selectivity.; Since the search for new acids is of great interest to chemists, Chapter 6 describes a new convenient acid that exhibits superacidity. Various electrophilic hydrocarbon transformations are described with emphasis on ionic hydrogenations. (Abstract shortened by UMI.)... |
