Kawaoka Amber M, Marks Tobin J
Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3113, USA.
J Am Chem Soc. 2004 Oct 13;126(40):12764-5. doi: 10.1021/ja045965n.
Organolanthanide-mediated hydrophosphination and ethylene polymerization are coupled in a catalytic cycle to produce diphenylphosphine-terminated polyethylenes. The resulting polymers were characterized by 1H, 13C, and 31P NMR, GPC, and DSC and compared spectroscopically to the model compound, 1-eicosyldiphenylphosphine oxide. High activities (107 g polymer/(mol Ln.atm ethylene.h)) and narrow polydispersities were observed in the polymerization/chain transfer process. Polyethylene molecular weights were found to be inversely proportional to diphenylphosphine concentration, supporting a chain transfer mechanism. The present discovery represents the first case in which an electron-rich phosphine functions efficiently as a chain transfer agent in a single-site fn/d0-mediated olefin polymerization process.
有机镧系元素介导的氢膦化反应和乙烯聚合反应在催化循环中偶联，以生成二苯基膦封端的聚乙烯。通过¹H、¹³C和³¹P NMR、GPC和DSC对所得聚合物进行了表征，并与模型化合物1-二十烷基二苯基氧化膦进行了光谱比较。在聚合/链转移过程中观察到了高活性（10⁷ g聚合物/（mol Ln·atm乙烯·h））和窄的多分散性。发现聚乙烯分子量与二苯基膦浓度成反比，这支持了链转移机理。本发现代表了首例富电子膦在单中心fⁿ/d⁰介导的烯烃聚合过程中有效用作链转移剂的情况。
