Supercritical CO2 and CHF3 as Alternative Solvents for Pollution Prevention

化学部的这一奖项支持弗吉尼亚理工学院和州立大学化学系的James M.Tanko博士关于使用超临界流体作为化学反应的环境友好溶剂的研究。该奖项是在1995年NSF/EPA环境研究伙伴关系的可持续环境活动技术中颁发的。将考察二氧化碳和氟仿作为自由基反应溶剂的潜力。预计这两种溶剂对自由基都是惰性的，并已知在中等温度和压力下变得超临界。该项目的目标是确定适用于超临界流体条件的自由基反应的范围和限制，开发合成高价值有机材料的新合成方法，并探索使用超临界流体对有机反应的基本物理原理的影响。许多有机反应是通过一种机理进行的，该机理涉及一种具有未配对电子的活性物种，称为自由基。例如，在碳氢化合物中添加氯或溴或延长碳氢链的反应。在这些反应中，重要的是溶剂不能与自由基反应。通常，溶剂在自由基物种的形成中也起着作用。在许多情况下，苯和四氯化碳是此类反应的有效溶剂，但它们对环境有害。在这项研究中，将测试两种环境友好的替代溶剂在涉及自由基的有机反应中的适用性。

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.