This award in the Chemistry Division supports research by Dr. James M. Tanko of the Chemistry Department, Virginia Polytechnic Institute and State University, on the use of supercritical fluids as environmentally benign solvents for chemical reactions. The award is made in the Technology for a Sustainable Environment activity of the 1995 NSF/EPA Partnership for Environmental Research. Carbon dioxide and fluoroform will be examined for their potential as solvents for radical reactions. Both solvents are expected to be inert toward free radicals and are known to become supercritical at moderate temperatures and pressures. The goals of the project are to identify the scope and limitations of radical reactions amenable to supercritical fluid conditions, to develop new synthetic methods for the synthesis of high-value organic materials, and to explore the implications of the use of supercritical fluids for fundamental physical principles of organic reactivity. Many organic reactions proceed by a mechanism which involves a reactive species with an unpaired electron called a free radical. Example reactions are those involving addition of chlorine or bromine to hydrocarbons or lengthening of hydrocarbon chains. In these reactions, it is important that the solvent not react with the free radical. Often the solvent also plays a role in the formation of the radical species. In many cases benzene and carbon tetrachloride are effective solvents for such reactions, but they are environmentally harmful. In this research two alternate solvents which are environmentally benign will be tested for suitability in organic reactions involving free radicals.
