Ravbar Miha, Koler Amadeja, Paljevac Muzafera, Krajnc Peter, Kolar Mitja, Iskra Jernej
Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna Pot 113, 1000 Ljubljana, Slovenia.
Faculty of Chemistry and Chemical Engineering, University of Maribor, Smetanova Ulica 17, 2000 Maribor, Slovenia.
ACS Omega. 2022 Apr 6;7(15):12610-12616. doi: 10.1021/acsomega.1c06318. eCollection 2022 Apr 19.
Palladium was immobilized on a highly porous copolymer of 4-vinylpyridine and divinylbenzene (polyHIPE-poly(high internal phase emulsion)) using palladium(II) acetate to obtain PolyPy-Pd with 6.1 wt % or 0.57 mmol Pd/g. The immobilized catalyst was able to catalyze the coupling of iodobenzene and phenylboronic acid in ethylene glycol monomethyl ether/water (3:1) within 4 h at rt and complete conversion was observed when 2.5 mol % of Pd per PhI was used. The reaction tolerated a wide range of substituents on the aromatic ring. Iodobenzene derivatives with electron-withdrawing substituents showed higher reactivity, while the opposite was true for the phenylboronic acid series. The polyHIPE-supported Pd catalyst was also used for the direct conversion of phenylboronic acid to biphenyl through an iodination/coupling reaction sequence. The recyclability of the heterogeneous catalyst was also optimized, and by finding a suitable combination of solvents for the loading of Pd, the reaction, and the isolation of the product, the solid-supported catalyst was completely regenerated and used in the next reaction with the same activity.
使用乙酸钯将钯固定在4-乙烯基吡啶和二乙烯基苯的高度多孔共聚物（聚HIPE-聚（高内相乳液））上，以获得含6.1 wt%或0.57 mmol Pd/g的聚吡啶-钯（PolyPy-Pd）。固定化催化剂能够在室温下于乙二醇单甲醚/水（3:1）中催化碘苯与苯硼酸的偶联反应，4小时内完成反应，当每摩尔碘苯使用2.5 mol%的钯时可观察到完全转化。该反应对芳环上的多种取代基具有耐受性。带有吸电子取代基的碘苯衍生物显示出更高的反应活性，而苯硼酸系列则相反。聚HIPE负载的钯催化剂还用于通过碘化/偶联反应序列将苯硼酸直接转化为联苯。非均相催化剂的可回收性也得到了优化，通过找到用于负载钯、进行反应以及分离产物的合适溶剂组合，固体负载催化剂得以完全再生，并以相同活性用于下一次反应。
