Rhodium catalyzed aqueous biphasic hydroformylation of naturally occurring allylbenzenes in the presence of water-soluble phosphorus ligands

• Eugenol, estragole and safrole were hydroformylated in an aqueous biphasic system.
• Small amounts of CTAB significantly accelerated the reaction.
• The regioselectivity can be controlled by water-soluble phosphorous ligands.
• TPPTS or BISBIS favour linear and BDPPETS or BDPPPTS favour branched aldehydes.
• The catalyst was recycled five times keeping activity and selectivity.

The rhodium-catalyzed hydroformylation of eugenol was performed in aqueous biphasic systems using various water soluble phosphines: TPPTS (triphenylphosphinetrisulphonated); BDPPETS (bisdiphenylphosphinoethanetetrasulphonated), BDPPPTS (bisdiphenylphosphinopropanetetrasulphonated) and BISBIS (diphosphane 2,2′-bis(diphenylphosphinomethyl)-1,1′-biphenyl disuphonated). The addition of the cationic surfactant CTAB (cetyltrimethylammonium bromide) increased the reaction rate; however, high surfactant concentrations unfavorably affected the reaction selectivity. The regioselectivity of the hydroformylation was strongly depended on the ligand nature. The procedure was successfully extended to other allylbenzenes, i.e., estragole and safrole, producing several fragrance compounds starting from the substrates easily available from natural bio-renewable resources.

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