Aqueous-phase hydroformylation of 1-octene using hydrophilic sulfonate salicylaldimine dendrimersDedicated to Professor David Cole-Hamilton on the occasion of his retirement and for his outstanding contribution to transition metal catalysis.Electronic supplementary information (ESI) available. See DOI: 10.1039/c2dt31471a

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 1 H NMR, 13 C 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 1 H NMR, 13 C 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). Preparation and characterization of water-soluble Rh( i ) metallodendrimers. Hydroformylation under aqueous biphasic conditions is achieved at mild temperature and pressure. Good activities and selectivities are exhibited.