Aqueous-phase hydroformylation of 1-octene using hydrophilic sulfonate salicylaldimine dendrimers
作者:Emma B. Hager、Banothile C. E. Makhubela、Gregory S. Smith
DOI:10.1039/c2dt31471a
日期:——
Water-soluble dendritic ligands based on tris-2-(5-sulfonato salicylaldimine ethyl)amine (5) and DAB-(5-sulfonato salicylaldimine) (6) (DAB = diaminobutane) were synthesized by means of Schiff base condensation and sulfonation reactions. These dendritic ligands were fully characterized by 1H NMR, 13C NMR and FT-IR spectroscopy, elemental analysis and mass spectrometry. Dendritic ligands (5 and 6) in combination with [RhCl(COD)]2 (COD = 1,5-cyclooctadiene) were evaluated in aqueous biphasic hydroformylation of 1-octene. New water-soluble mononuclear 5-sulfonato propylsalicylaldimine Rh(I) complexes (7 and 8) were synthesized and characterized using 1H NMR, 13C NMR and FT-IR spectroscopy, elemental analysis as well as mass spectrometry. These complexes were applied as catalyst precursors in aqueous biphasic hydroformylation reactions. All the catalyst precursors were active in the hydroformylation of 1-octene under the investigated conditions. Optimal conditions were realized at 75 °C (40 bars), where the best selectivity for aldehydes was noticed. Catalyst recycling was achieved up to 5 times with minimal loss in conversion and consistent chemoselectivities and regioselectivities. Less Rh leaching was observed in the dendritic systems (5 and 6)/[RhCl(COD)]2 as compared to mononuclear catalyst precursors (7 and 8) as determined by inductively coupled plasma-mass spectrometry (ICP-MS).
通过希夫碱缩合和磺化反应,合成了基于三-2-(5-磺酸水杨醛亚胺乙基)胺(5)和 DAB-(5-磺酸水杨醛亚胺)(6)(DAB = 二氨基丁烷)的水溶性树枝状配体。这些树枝状配体通过 1H NMR、13C NMR 和傅立叶变换红外光谱、元素分析和质谱法进行了全面表征。树枝状配体(5 和 6)与 [RhCl(COD)]2(COD = 1,5-环辛二烯)的组合在 1-辛烯的水性双相加氢甲酰化中进行了评估。合成了新的水溶性单核 5 磺化丙水杨醛亚胺 Rh(I) 复合物(7 和 8),并使用 1H、13C、NMR 和 FT-IR 光谱、元素分析以及质谱法对其进行了表征。这些复合物被用作水基双相加氢甲酰化反应的催化剂前体。在研究条件下,所有催化剂前体在 1-辛烯的加氢甲酰化反应中都具有活性。最佳条件在 75 °C (40 巴)下实现,在此条件下,醛的选择性最佳。催化剂可循环使用 5 次,转化率损失极小,化学选择性和区域选择性保持一致。通过电感耦合等离子体质谱法(ICP-MS)测定,与单核催化剂前体(7 和 8)相比,树枝状体系(5 和 6)/[RhCl(COD)]2 中的 Rh 浸出较少。