| The catalytic selectivity of α-alkene hydrocarbons in a sulfuric acid system can be enhanced by adding either of the sulfur-containing amino acids, methionine or cysteine. When added in 1 molal quantities, the amino acid acts as a promoter, which captures the labile carbocation, until it is transferred to another nucleophile. The present work was undertaken to characterize the extent of selectivity of this novel catalyst system, while determining its mechanistic activity. Acid strength effects, oligomerization and alkylation studies with alkenes were conducted to understand the extent of catalytic ability. The measurement of acid strength and activity extent was determined by the Hammett acidity function. The reactant products were determined by a gas chromatograph-mass spectrometer instrument (GC-MS), and the mechanism was determined by nuclear magnetic resonance (NMR) isotope effects.; The reaction products of various α-alkenes and mixed alkenes under acid conditions with and without the amino acids were studied. The finding that the methionine did in fact act as an acceptor for the alkene, and transfers it to another alkene via a carbonium ion has been demonstrated. It was also determined that hydride transfers, and molecular rearrangements were minimized while using this method. This catalyst system has the potential for use primarily in the hydrocarbon industry, where branched products in the C8–C 12 range make useful fuel enhancers. Similar to other catalytic systems, this system is susceptible to poisoning, particularly with saturated, acid soluble compounds, as determined by multi-pass and recycling experiments. |
