Bifunctional Free Radical Initiators and Azoxyalkane Cyclizations

这项研究的重点有三个方面。首先，将合成含有双官能团和三官能团自由基引发剂的偶氮和酯，并研究它们作为星形聚合物和嵌段共聚物的前体，以及嵌段界面含有官能团的嵌段共聚物。其次，含偶氮基分子的自由基化学将被检查，特别强调确定，取决于偶氮基的位置，分子内环化和乙烯演化的机制。最后，将阐明卤素与偶氮烷烃和1,2-二烷基肼形成配合物的机理，并对所产生的加合物的自由基化学进行研究。将向研究生和博士后介绍上述有机分子的自由基化学，以及自由基聚合。通过这个奖项，有机和大分子化学项目支持莱斯大学化学系保罗·恩格尔博士的研究和教育活动。Engel博士将专注于合成和表征含有两个或多个偶氮或酯基团的有机分子。用热或光激活这些基团会导致称为自由基的高活性位点。通过定位分子内的偶氮或酯基团，从而确定自由基产生的位置，恩格尔博士将研究同一分子内的两个位点形成环状分子的机制，以及一个分子上的位点与另一个分子反应以传播自由基形成的机制，以及随后具有新分子形状和组成的聚合物的生长。Engel博士的教育活动包括培训研究生和博士后学生合成含有偶氮和酯基团的分子，它们的活化形成自由基，以及这些反应中间体的后续化学特性。

The focus of this research is three fold. First, azo and perester containing bi- and tri-functional free-radical initiators will be synthesized and examined as precursors to star polymers, and block copolymers containing functional groups at the block interfaces. Second, the radical chemistry of molecules containing an azoxy group will be examined with a specific emphasis on determining, depending on the position of azoxy group, the mechanisms of intramolecular cyclization and ethylene evolution. Lastly, the mechanism by which halogens form complexes with azoalkanes and 1,2-dialkylhydrazines will be elucidated and the radical chemistry of the resulting adduct examined. Graduate and postdoctoral students will be introduced to the free radical chemistry of the aforementioned organic molecules, and free radical polymerization. With this award, the Organic and Macromolecular Chemistry Program supports the research and educational activities of Dr. Paul Engel of the Department of Chemistry at Rice University. Dr. Engel will focus his research on the synthesis and characterization of organic molecules containing two or more azo or perester groups. Activating these groups with either heat or light leads to highly reactive sites referred to as free radicals. By positioning the azo or perester groups within the molecule, and thereby defining the sites at which the free radicals are generated, Dr. Engel will examine the mechanism by which two sites within the same molecule couple to form a cyclic molecule, and the mechanisms by which sites on one molecule react with another molecule to propagate the formation of the radical, and the subsequent growth of polymers with new molecular shapes and composition. Dr. Engel's educational activities involve training graduate and postdoctoral students in the synthesis of molecules containing azo and perester groups, their activation to form free radicals, and the characterization of the subsequent chemistry of these reactive intermediates.