The role of Pd nanoparticles in ionic liquid in the Heck reaction
The role of Pd nanoparticles in ionic liquid in the Heck reaction
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DOI：
10.1021/ja0430043
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发表时间：
2005-03-16
影响因子：
15
通讯作者：
Dupont, J
中科院分区：
文献类型：
--
作者：
Cassol, CC;Umpierre, AP;Dupont, J
直径约 2 nm 的 Pd(0) 纳米粒子固定在 1-正丁基-3-甲基咪唑鎓六氟磷酸盐离子液体中，是芳基卤化物与丙烯酸正丁酯偶联的有效催化剂前体。催化反应后离子液体催化溶液的原位 TEM 分析显示形成了较大的纳米颗粒（∼6 nm）。通过 ICP-AS 检查芳基化反应过程中有机相中的钯含量，结果显示，在低底物转化率下，金属从离子相浸出到有机相（高达 34%），而在较高转化率下，金属浸出率降至 5−8%。这些结果强烈表明 Pd(0) 纳米颗粒可作为“均质”催化活性物质的储存库。
Pd(0) nanoparticles with ∼2 nm diameter, immobilized in 1-n-butyl-3-methylimidazolium hexafluorophosphate ionic liquid, are efficient catalyst precursors for coupling of aryl halides withn-butylacrylate. In situ TEM analysis of the ionic liquid catalytic solution after the catalytic reaction shows the formation of larger nanoparticles (∼6 nm). The palladium content in the organic phase during the arylation reaction was checked by ICP-AS and shows significant metal leaching (up 34%) from the ionic phase to the organic phase at low substrate conversions and drops to 5−8% leaching at higher conversions. These results strongly suggest that the Pd(0) nanoparticles serve as a reservoir of “homogeneous” catalytic active species.