Transition Metal-Catalyzed Olefin Polymerization: Mechanistic Studies and Catalyst Design

过渡金属催化烯烃聚合：机理研究和催化剂设计

• 批准号: 8705534
• 负责人: Maurice Brookhart
• 金额: $ 27.23万
• 依托单位: University of North Carolina at Chapel Hill
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-09-01 至 1991-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8705534&HistoricalAwards=false
• 关键词: Transition; Metal; Catalyzed; Olefin; Polymerization

One of the most important industrial processes is the conversion of olefins, i.e. hydrocarbon molecules containing double bonds, to polymers. Examples of two such polymers are polyethylene and polypropylene. Although organometallic catalysts have been used in the commercial polymerization of olefins for several decades, remarkably little is understood about the detailed mechanism of the catalytic processes, and catalyst design has been largely empirical. The Principal Investigator has developed chemistry which promises to yield mechanistic details of olefin polymerization and allow more logical design of catalyst systems. Migratory insertion reactions of transition metal alkyl olefin complexes are key transformations in hetero- and homogeneous olefin polymerization reactions and numerous stoichiometric carbon-carbon bond forming reactions. The proposed work focuses on understanding fundamental aspects of this reaction coupled with preparation and study of new olefin polymerization catalysts. The Principal Investigator has obtained results recently which suggest that there is a relationship between the structure and dynamics of ethylene hydride complexes and their alkyl analogs and that ethylene hydride complexes which exist as bridged or agostic structures can serve as ethylene polymerization catalysts. A cobalt complex possessing an agostic ethyl group has been discovered which catalyzes living polymerization of ethylene. Goals of the research are (1) to synthesize and explore the reactivity and catalytic activity of cationic and neutral Co(III) complexes containing an agostic ethyl group, a neutral or anionic two-electron donor group, and either a Cp or a Cp* ligand, (2) to prepare new agostic ethylene hydride complexes and evaluate these species as olefin polymerization catalysts, (3) to develop these new complexes for living polymerization of a diverse group of olefins, with emphasis on correlations of mechanistic features with polymer structure and utilizing living systems for block and copolymerization, and 4) to develop methods to functionalize or cap one or both ends of the polymer chain with functional groups.

最重要的工业过程之一是将烯烃(即含有双键的碳氢分子)转化为聚合物。两种这种聚合物的例子是聚乙烯和聚丙烯。尽管有机金属催化剂在烯烃的工业聚合中已经使用了几十年，但对催化过程的详细机理了解很少，催化剂设计在很大程度上是经验的。首席研究人员开发了化学，有望产生烯烃聚合的机理细节，并允许更合理的催化剂系统设计。过渡金属烷基烯烃络合物的迁移插入反应是多相和均相烯烃聚合反应以及大量化学计量碳-碳键形成反应中的关键转化反应。建议的工作侧重于了解该反应的基本方面，以及新型烯烃聚合催化剂的制备和研究。首席研究员最近的研究结果表明，乙烯氢化物络合物的结构和动力学与它们的烷基类似物有关，以桥联或无规结构存在的乙烯氢化物络合物可以作为乙烯聚合催化剂。发现了一种具有无组分乙基的钴络合物，它能催化乙烯的活性聚合。本研究的目标是(1)合成和探索含有阳离子乙基、中性或阴离子双电子给体、CP或Cp*配体的阳离子和中性Co(III)配合物的反应活性和催化活性，(2)合成新的阳离子乙二醇络合物，并评价这些物种作为烯烃聚合催化剂的性能。(3)开发用于不同基团的烯烃活性聚合的新的络合物，重点是机械特性与聚合物结构的相关性以及利用活性体系进行嵌段和共聚，以及4)开发用官能团对聚合物链的一端或两端进行官能化或封端的方法。