New water-soluble Schiff base ligands based on β-cyclodextrin for aqueous biphasic hydroformylation reaction

The synthesis of water-soluble rhodium(I) salicylaldiminato and salicylhydrazonic complexes has been achieved employing two preparative routes. Schiff base condensation between 6 A -deoxy-6 A -amino-β-CD or 6 A -deoxy-6 A -hydrazino-β-CD and 5-sodiosulfonato-2-hydroxybenzaldehyde (sulfonated salicylaldehyde) ( 1 ) or 5-sodiosulfonato-3- tert -butyl-2-hydroxybenzaldehyde (sulfonated t Bu-salicylaldehyde) ( 2 ) led to the formation of the corresponding imine or hydrazone ligands ( 3 , 4 , 5 and 6 ). Reaction of [Rh(COD) 2 + BF 4 − ] with these new ligands in an alkaline solution formed the corresponding rhodium complexes quantitatively. These rhodium(I) complexes could also be prepared in one-pot by mixing, in stoichiometric proportions, the modified β-CDs with the sulfonated salicylaldehyde and with the rhodium precursor in an alkaline solution at room temperature. These rhodium complexes were applied as catalysts in the aqueous biphasic hydroformylation of 1-decene as a model reaction.