Bifunctional Free Radical Initiators and Azoxyalkane Cyclizations

本研究的重点有三个方面。首先，我们将合成含有双官能团和三官能团自由基引发剂的偶氮和双酯，并将其作为星形聚合物和嵌段共聚物的前驱体。其次，将考察含有偶氮基的分子的自由基化学，重点是根据偶氮基的位置确定分子内环化和乙烯释放的机制。最后，将阐明卤素与偶氮烷烃和1，2-二烷基肼形成络合物的机理，并对生成的加合物的自由基化学进行研究。研究生和博士后将被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，有机和高分子化学项目支持莱斯大学化学系Paul Engel博士的研究和教育活动。恩格尔博士将把他的研究重点放在含有两个或多个偶氮基团或酯基团的有机分子的合成和表征上。用热或光激活这些基团都会导致被称为自由基的高活性部位。通过在分子中定位偶氮基团或酯基团，从而定义产生自由基的位置，Engel博士将研究同一分子中的两个位置结合形成环状分子的机制，以及一个分子上的位置与另一个分子反应以传播自由基的形成以及具有新的分子形状和组成的聚合物随后增长的机制。恩格尔博士的教育活动包括培训研究生和博士后合成含有偶氮基团和酯基团的分子，激活它们形成自由基，以及这些活性中间体随后的化学特征。

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.