Rhodium catalyzed hydroformylation assisted by cyclodextrins in biphasic medium: Can sulfonated naphthylphosphanes lead to active, selective and recyclable catalytic species?

• Sulfonation of naphthylphosphanes leads to aqueous ligands with a sulfonation degree around 2.
• 2-Naphthylphosphanes lead to active and recyclable catalytic systems.
• 1-Naphthylphosphanes lead to a decoordination of the phosphanes from the metal center under CO/H2 atmosphere.
• Displacements toward low-coordinated species were observed in the presence of RAME-β-CD.

New sulfonated naphthylphosphanes having an average sulfonation degree around 2 have been synthetized and tested as ligand in the aqueous biphasic Rh-catalyzed hydroformylation of 1-decene assisted by randomly methylated β-cyclodextrins. All these water-soluble phosphanes associated to a rhodium precursor were able to perform aqueous hydroformylation of 1-decene. The best results in terms of catalyst recovery and recycling were obtained with sulfonated 2-naphthylphosphanes. With sulfonated 1-naphthylphosphanes, formation of low-coordinated catalytic species leading to a catalyst leaching in the organic phase was postulated. These results were rationalized by considering that sulfonated 1-naphthylphosphanes are bulkier ligands than sulfonated 2-naphthylphosphanes.

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