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Recyclable Palladium-Loaded Hyperbranched Polytriazoles as Efficient Polymer Catalysts for Heck Reaction
ACS Applied Polymer Materials ( IF 4.4 ) Pub Date : 2019-12-24 , DOI: 10.1021/acsapm.9b01011
Weiping Gan 1 , Hui Xu 1 , Xiuyu Jin 1 , Xiaosong Cao 1 , Haifeng Gao 1
Affiliation  

Two polytriazole-based hyperbranched polymers (HBPs) with different molecular weights were prepared by chain-growth Cu-catalyzed azide–alkyne cycloaddition (CuAAC) polymerization of an AB2 monomer. Subsequent chain-end-capping reactions with alkynyl-containing ligands, such as 2-ethynylpyridine, phenylacetylene and alkyne-terminated polyethylene glycol (ay-PEG), produced a small library of HBPs that were applied to complex with Pd(OAc)2 and produce Pd-loaded HBP catalysts for efficient Heck reaction of iodobenzene and styrene. The effects of HBP terminal ligand groups and polymer molecular weights were explored on the Heck reaction performance. At the same molecular weight, the HBP-based catalyst with PEG or pyridyl terminal groups showed faster Heck reaction kinetics as comparing to those with phenyl terminal groups. Meanwhile, higher-molecular-weight polymer catalysts exhibited faster catalytic kinetics than lower-molecular-weight ones. Comparing to the small-molecule monotriazole ligands, these polytriazole-based HBPs demonstrated higher catalytic efficiency due to multigroup cooperative effect, confirming that the polytriazole cluster was a boosting ligand for the catalytic Heck reaction. These HBP catalysts exhibited good recyclability as the catalyst after five-time recycling still achieved over 90% conversion of the reaction substrate.

中文翻译:

可回收钯负载的超支化聚三唑作为高效的Heck反应聚合物催化剂

通过链增长的Cu催化的AB 2单体的叠氮化物-炔烃环加成(CuAAC)聚合反应,制备了两种分子量不同的聚三唑基超支化聚合物(HBP)。随后与含炔基的配体(如2-乙炔基吡啶,苯乙炔和炔基封端的聚乙二醇(ay-PEG))进行链端封端反应,产生了一个小的HBP库,可用于与Pd(OAc)2形成复合物并生产负载钯的HBP催化剂,以实现碘代苯与苯乙烯的高效Heck反应。探讨了HBP末端配体基团和聚合物分子量对Heck反应性能的影响。在相同分子量下,具有PEG或吡啶基端基的HBP基催化剂与具有苯基端基的HBP反应动力学相比,具有更快的Heck反应动力学。同时,高分子量的聚合物催化剂比低分子量的催化剂表现出更快的催化动力学。与小分子单三唑配体相比,这些基于聚三唑的HBP由于具有多基团协同作用而显示出更高的催化效率,证实了聚三唑簇是催化Heck反应的促进配体。
更新日期:2019-12-25
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