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Alternating Ring-Opening Metathesis Copolymerization by Grubbs-TypeInitiators with Unsymmetrical N-Heterocyclic Carbenes

机译:Grubbs型引发剂与不对称N杂环卡宾交替进行的开环易位共聚合

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摘要

A series of Ru~(IV)-alkylidenesbased on unsymmetrical imidazolin-2-ylidenes, that is, [RuCl_2{1-(2,4,6-trime-thylphenyl)-3-R-4,5-dihydro-(3H)-imi-dazol-1-ylidene } (CHPh)(pyridin)] (R =CH2Ph (5), Ph (6), ethyl (7), methyl(8)), have been synthesized. These andthe parent initiators [RuCl_2(PCy_3){1-(2,4,6-trimethylphenyl)-3-R-4,5-dihy- dro-(3H)-imidazol-1-ylidene}-(CHC_6H_5)](R =CH_2C_6H_5(1),C_6H_5 (2), ethyl (3)) were used for the alter-nating copolymerization of norborn-2-ene (NBE) with cis-cyclooctene (COE)and cyclopentene (CPE), respectively.Alternating copolymers, that is, poly-(NBE-alt-COE)_n and poly(NBE-alt-CPE)_n containing up to 97 and 91 % al-ternating diads, respectively, were ob-tained. The copolymerization parame-ters of the alternating copolymerizationof NBE with CPE under the action ofinitiators 1-3 and 5-8 were determinedby using both a zero- and first-orderMarkov model. Finally, kinetic investi-gations using initiators 1-3, 6, and 7 were carried out. These revealed thatin contrast to the 2nd-generationGrubbs-type initiators 1-3 the corre-sponding pyridine derivatives 6 and 7represent fast and quantitative initiat-ing systems. Hydrogenation of poly-(NBE-alt-COE)_n yielded a fully satu-rated, hydrocarbon-based polymer. Itsbackbone can formally be derived by1-olefin polymerization of CPE (1,3-in-sertion) followed by five ethylene unitsand thus serves as an excellent modelcompound for 1-olefin polymerization-derived copolymers.
机译:基于不对称咪唑啉-2-亚烷基的一系列Ru〜(IV)-亚烷基,即[RuCl_2 {1-(2,4,6-trime-thylphenyl)-3-R-4,5-dihydro-(3H )-咪唑-亚唑-1-基}(CHPh)(吡啶)](R = CH2Ph(5),Ph(6),乙基(7),甲基(8))。这些和母体引发剂[RuCl_2(PCy_3){1-(2,4,6-三甲基苯基)-3-R-4,5-二氢-(3H)-咪唑-1-亚基}-(CHC_6H_5)]( R = CH_2C_6H_5(1),C_6H_5(2),乙基(3))分别用于降冰片-2-烯(NBE)与顺式环辛烯(COE)和环戊烯(CPE)的交替共聚。获得了分别含有多达97%和91%的交替二单元的聚-(NBE-alt-COE)_n和聚(NBE-alt-CPE)_n的共聚物。通过使用零阶和一阶马尔可夫模型,确定了在引发剂1-3和5-8的作用下NBE与CPE交替共聚的共聚参数。最后,使用引发剂1-3、6和7进行动力学研究。这些表明与第二代Grubbs型引发剂1-3相反,相应的吡啶衍生物6和7代表快速和定量的引发体系。聚(NBE-alt-COE)_n的氢化产生完全饱和的基于烃的聚合物。它的主链可以通过CPE的1-烯烃聚合反应(依次为1,3,3-部分)再由五个乙烯单元衍生而来,因此可作为衍生自1-烯烃聚合反应的共聚物的优良模型化合物。

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