Date of Award

6-1999

Degree Name

Master of Arts

Department

Chemistry

First Advisor

Dr. John E. Chateauneuf

Second Advisor

Dr. Marc W. Perkovic

Third Advisor

Dr. Yi-Ping Liu

Access Setting

Masters Thesis-Open Access

Abstract

Recent interest in the use of supercritical CO2 as an environmentally benign reaction medium has included the development of solvent systems that may support polar and ionic chemistry. Carbocations are key intermediate in a variety of synthetically important reactions and characterization of their reactivity is the focus of this work. UV-visible absorption, and steady-state and time-resolved fluorescence spectroscopy has been used to identify and monitor the reaction kinetics of 9- phenylxanthenium carbocation. The arylcarbocation is conveniently generated from 9- phenylxanthen-9-ol in supercritical CO2 under mildly acidic conditions. Under these conditions 9-phenylxanthenium ion is extremely stable and persists for days, as indicated by observation of its visible absorption. This stability allows for the investigation of excited state carbocation reactivity and the investigation of electrontransfer reactions with aromatic compounds. These reactions have been used to probe the influence of solvent and solvation effects on this category of reaction chemistry in supercritical CO2.

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