Organic Free Radical Chemistry

这项来自有机动力学项目的拨款支持了韦恩州立大学马丁·e·纽科姆教授的持续工作。将研究一些非常快的有机自由基反应，包括在低粘度溶剂中接近扩散速率的二阶自由基捕获反应和在室温下寿命短至几皮秒的高活性自由基的一级重排。已报道的测定碳中心自由基重排速率常数的间接动力学方法将进一步发展，使其在室温下的最终动力学分辨率约为1皮秒，即使在无法进行直接动力学研究时也将有用。间接方法将推广到氧基自由基的脱羧和氮中心自由基的反应。芳基取代环丙基羰基自由基、取代5-己烯基自由基和立方羰基自由基的快速重排将被充分表征。自由基重排在含铁酶及其模型的机理研究中的应用。直接激光闪光动力学方法也将用于研究酰基自由基的脱羧以及碳中心和氮中心自由基的重排。有机自由基，具有奇数电子的中性物质，将被研究。这些活性物质将由稳定的前体分子热裂解产生。将发展一种间接测定自由基反应速率的方法。这种新的速率测量方法将允许对含碳和含氮自由基的反应进行检测，而以前这些反应速度太快而不能方便地进行研究。这项新技术将用于检测含铁酶及其模型。该结果有望为涉及自由基中间体的各种有机和生物反应提供有价值的信息。

This grant from the Organic Dynamics Program supports the continuing work of Professor Martin E. Newcomb at Wayne State University. A number of very fast organic radical reactions will be studied including second order radical trapping reactions that approach the rate of diffusion in low viscosity solvents and first order rearrangements of highly reactive radicals that have lifetimes at room temperature as short as several picoseconds. An indirect kinetic method for determining rate constants of carbon- centered radical rearrangements which has been reported will be further developed such that it will have an ultimate kinetic resolution at room temperature of about one picosecond and will be useful even when direct kinetic studies are not possible. The indirect method will be extended to decarboxylations of acyloxy radicals and reactions of nitrogen-centered radicals. Fast rearrangements of aryl-substituted cyclopropyl-carbinyl radicals, substituted 5-hexenyl radicals and the cubylcarbinyl radical will be fully characterized. Applications of radical rearrangements in mechanistic studies of iron-containing enzymes and their models will be initiated. A direct laser-flash kinetic method will also be utilized to study decarboxylations of acyloxy radicals as well as rearrangements of carbon- and nitrogen-centered radicals. %%% Organic radicals, neutral species with an odd number of electrons, will be studied. These reactive species will be generated by thermolysis of stable precursor molecules. An indirect method of determining the rates of reactions of the radicals will be developed. This new rate measurement method will allow examinations of reactions of carbon and nitrogen containing radicals which were previously too rapid to study conveniently. Application of this new technology to examine iron-containing enzymes and their models will be initiated. The results are expected to provide valuable information that can be used in a wide variety of organic and biological reactions that involve radical intermediates.