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Mechanistic Studies of Redox-Switchable Copolymerization of Lactide and Cyclohexene Oxide by a Zirconium Complex
Organometallics ( IF 2.5 ) Pub Date : 2017-11-07 00:00:00 , DOI: 10.1021/acs.organomet.7b00672 Stephanie M. Quan 1 , Junnian Wei 1 , Paula L. Diaconescu 1
Organometallics ( IF 2.5 ) Pub Date : 2017-11-07 00:00:00 , DOI: 10.1021/acs.organomet.7b00672 Stephanie M. Quan 1 , Junnian Wei 1 , Paula L. Diaconescu 1
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Several aspects of the copolymerization of l-lactide (LA) and cyclohexene oxide (CHO) by a redox-switchable zirconium catalyst, (salfan)Zr(OtBu)2 (salfan = 1,1′-bis(2-tert-butyl-6-N-methylmethylenephenoxy)ferrocene), were examined, such as the mechanism of cyclohexene oxide polymerization, the reactivity of [(salfan)Zr(OtBu)2][BArF] (BArF = tetrakis(3,5-bis(trifluoromethyl)phenyl)borate) toward lactide, and comonomer effects on polymerization rates. Experimental methods and DFT calculations indicate that the likely mechanism of CHO polymerization by [(salfan)Zr(OtBu)2][BArF] is coordination insertion and not a cationic pathway, as employed by the majority of cationic catalysts. Furthermore, DFT calculations showed that the polymerization of LA by [(salfan)Zr(OtBu)2][BArF] is not thermodynamically favored, in agreement with experimental results. Finally, we found that the conversion times of CHO or LA from block to block correlate with the amount of monomer left from the previous block rather than other factors.
中文翻译：
锆配合物对丙交酯和环己烯氧化物进行氧化还原可切换共聚的机理研究
的共聚的几个方面升通过氧化还原可切换锆催化剂丙交酯（LA）和氧化环己烯（CHO），（salfan基）Zr（O吨丁基）2（salfan = 1,1'-双（2-叔-丁基-6- N-甲基亚甲基苯氧基）二茂铁）进行了研究，如氧化环己烯的聚合机理，[（salfan）Zr（O t Bu）2 ] [BAr F ]（BAr F = tetrakis（3， 5-双（三氟甲基）苯基）硼酸酯对丙交酯，共聚单体对聚合速率有影响。实验方法和DFT计算表明，[（salfan）Zr（O t Bu）2可能是CHO聚合的机理。[BAr F ]是配位插入，而不是大多数阳离子催化剂所采用的阳离子途径。此外，DFT计算表明，[（salfan）Zr（O t Bu）2 ] [BAr F ]引起的LA的聚合反应在热力学上不受欢迎，与实验结果一致。最后，我们发现CHO或LA从嵌段到嵌段的转化时间与前一个嵌段剩余的单体量相关，而不是其他因素。
更新日期：2017-11-07
中文翻译：
锆配合物对丙交酯和环己烯氧化物进行氧化还原可切换共聚的机理研究
的共聚的几个方面升通过氧化还原可切换锆催化剂丙交酯（LA）和氧化环己烯（CHO），（salfan基）Zr（O吨丁基）2（salfan = 1,1'-双（2-叔-丁基-6- N-甲基亚甲基苯氧基）二茂铁）进行了研究，如氧化环己烯的聚合机理，[（salfan）Zr（O t Bu）2 ] [BAr F ]（BAr F = tetrakis（3， 5-双（三氟甲基）苯基）硼酸酯对丙交酯，共聚单体对聚合速率有影响。实验方法和DFT计算表明，[（salfan）Zr（O t Bu）2可能是CHO聚合的机理。[BAr F ]是配位插入，而不是大多数阳离子催化剂所采用的阳离子途径。此外，DFT计算表明，[（salfan）Zr（O t Bu）2 ] [BAr F ]引起的LA的聚合反应在热力学上不受欢迎，与实验结果一致。最后，我们发现CHO或LA从嵌段到嵌段的转化时间与前一个嵌段剩余的单体量相关，而不是其他因素。
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