首页> 外文期刊>Reactive & Functional Polymers >Functional gel-type resin based palladium catalysts: The role of polymer properties in the hydrogenation of the C = C bond of maleic and fumaric acids, the isomers of dicarboxylic acids
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Functional gel-type resin based palladium catalysts: The role of polymer properties in the hydrogenation of the C = C bond of maleic and fumaric acids, the isomers of dicarboxylic acids

机译:功能性凝胶型树脂基钯催化剂:聚合物性质在马来酸和富马酸(二羧酸的异构体)的C = C键的氢化中的作用

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摘要

Functional gel-type resins (OFP) composed of 2-hydroxyethyl methacrylate (HEMA, 20 mol%), styrene (60-77 mol%) and diethylene glycol dimethacrylate, the crosslinking reagent (DEGDMA, 3-20 mol%) are used as supports for palladium catalysts (0.25-2 wt% Pd). The influence of polymer mass expansion on the activity of Pd/OFP catalysts in the hydrogenation of cis- and trans-isomsrs, of unsaturated dicarboxylic acids, maleic (MA) and fumaric (FA), is examined. Starting polymer swells very well in THF and this solvent is used in the hydrogenation experiments. Swelling ability of polymer decreases after insertion of palladium ions due to the crosslinking effect. Reduction of Pd/OFP by NaBH_4 leads to further decrease in swelling ability of polymer caused by the changes in polymer structure observed in FTIR spectroscopy. In the reduced form of the catalysts the nano-particles of Pd (2-3 nm) are formed. Hydrogenation experiments performed in a wide range of operating conditions (Pd loading, catalysts concentration, crosslinking degree of polymer, the size of catalysts grains) show that the swelling of polymer mass during the hydrogenation is a crucial factor for activity of Pd/OFP catalysts. When the catalyst does not swell, the rates of hydrogenation for both isomers are practically the same. They differ only when the catalysts grains are in swollen state. Much higher rate of hydrogenation is observed for MA (the cis-iso-mer) than for FA (the trans-isomer). This is related to easier penetration of cis-isomer (MA) inside the bulk of the polymer mass which results in more effective utilization of substrates, MA and FA, when present in THF both enhance the expansion of polymer mass but especially cis-isomer, MA. Substrate effect is attributed to the interaction between functional groups present in the reduced catalysts and the hydrogenated reagents, maleic or fumaric acids.
机译:由甲基丙烯酸2-羟乙酯(HEMA,20 mol%),苯乙烯(60-77 mol%)和二甘醇二甲基丙烯酸酯,交联剂(DEGDMA,3-20 mol%)组成的功能性凝胶型树脂(OFP)被用作钯催化剂的载体(0.25-2 wt%Pd)。在顺式和反式异构体,不饱和二元羧酸,马来酸(MA)和富马酸(FA)的氢化过程中,研究了聚合物质量膨胀对Pd / OFP催化剂活性的影响。起始聚合物在THF中溶胀非常好,该溶剂用于氢化实验中。插入钯离子后,由于交联作用,聚合物的溶胀能力降低。 NaBH_4对Pd / OFP的还原导致FTIR光谱中观察到的聚合物结构变化导致聚合物溶胀能力进一步降低。在催化剂的还原形式中,形成了Pd的纳米粒子(2-3纳米)。在广泛的操作条件(Pd负载,催化剂浓度,聚合物的交联度,催化剂颗粒的大小)下进行的氢化实验表明,氢化过程中聚合物质量的溶胀是Pd / OFP催化剂活性的关键因素。当催化剂不溶胀时,两种异构体的氢化速率实际上是相同的。它们仅在催化剂颗粒处于溶胀状态时才不同。观察到MA(顺式异构体)的氢化速率远高于FA(反式异构体)的氢化速率。这与顺式异构体(MA)易于渗透到大部分聚合物中有关,这导致底物MA和FA更有效地利用,当存在于THF中时,MA和FA均可提高聚合物质量,尤其是顺式异构体的膨胀,嘛。底物作用归因于还原的催化剂中存在的官能团与氢化试剂马来酸或富马酸之间的相互作用。

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