Regioselective Carbyne Transfer to Ring-Opening Alkyne Metathesis Initiators Gives Access to Telechelic Polymers,Journal of the American Chemical Society

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Regioselective Carbyne Transfer to Ring-Opening Alkyne Metathesis Initiators Gives Access to Telechelic Polymers
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2017-05-17 00:00:00 , DOI: 10.1021/jacs.7b02225
Stephen von Kugelgen ₁ , Renee Sifri ₁ , Donatela Bellone ₁ , Felix R. Fischer _{1,

2,

3}

Affiliation

Regioselective carbyne-transfer reagents derived from (3,3,3-trifluoroprop-1-yn-1-yl)benzene give access to functionalized ring-opening alkyne metathesis polymerization (ROAMP) initiators [R-C₆H₄C≡Mo(OC(CH₃)(CF₃)₂)₃] featuring electron-donating or -withdrawing substituents on the benzylidyne. Kinetic studies and linear free-energy relationships reveal that the initiation step of the ring-opening alkyne metathesis polymerization of 5,6,11,12-tetradehydrobenzo[a,e][8]annulene exhibits a moderate positive Hammett reaction constant (ρ = +0.36). ROAMP catalysts featuring electron-withdrawing benzylidynes not only selectively increase the rate of initiation (k_i) over the rate of propagation (k_p) but also prevent undesired intra- and intermolecular chain-transfer processes, giving access to linear poly-(o-phenylene ethynylene) with narrow molecular weight distribution. The regioselective carbyne transfer methodology and the detailed mechanistic insight enabled the design of a bifunctional ROAMP-reversible addition–fragmentation chain-transfer (RAFT) initiator complex. ROAMP followed by RAFT polymerization yields hybrid poly-(o-phenylene ethynylene)-block-poly-(methyl acrylate) block copolymers.

中文翻译：

区域选择性碳烯转移到开环炔烃复分解引发剂使获得远螯聚合物

衍生自区域选择性碳炔-转移试剂（3,3,3-三氟丙-1-炔-1-基）苯授予访问官能开环炔易位聚合（ROAMP）引发剂[RC ₆ H ^ ₄ C≡Mo（OC（ CH ₃）（CF ₃）₂）₃ ]的特征在于在亚苄基上的给电子或吸电子取代基。动力学研究和线性自由能关系揭示了5,6,11,12-四脱氢苯并[ a，e]的开环炔烃复分解聚合的引发步骤] [8]环戊烯表现出中等正的Hammett反应常数（ρ= +0.36）。ROAMP催化剂设有吸电子benzylidynes不仅选择性地增加起始的速率（ķ_我）上传播（速度ķ _p），而且还防止不期望的分子内和分子间的链转移过程，从而获得线性聚- （ø -亚苯基亚乙炔基）具有窄的分子量分布。区域选择性卡宾转移方法和详细的机理见解使设计出双功能ROAMP可逆加成-断裂链转移（RAFT）引发剂复合物成为可能。ROAMP随后RAFT聚合得到的混合的聚- （ø-亚苯基乙炔基）-嵌段-聚（丙烯酸甲酯）嵌段共聚物。

更新日期：2017-05-25

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