Selectivity tuning using Rh/PTABS catalytic system for the hydroformylation of eugenol

Rhodium catalyzed hydroformylation of eugenol was carried out by using PTABS (4-(1,3,5-triaza-7-phosphaadamantan-1-ium-1-yl)butane-1-sulfonate) as a water-soluble ligand and CTAB (cetyltrimethylammonium bromide) as a phase transfer agent. The reaction conditions had a direct impact on the chemoselectivity of the system, which was capable of the formation of a variety of products; nevertheless, aldehyde yields of up to 93% were obtained with appropriate selectivity tuning. The inclusion of a water-insoluble promoter ligand, xantphos along with PTABS improved the regioselectivity of the system manifold and accelerated the reaction through interfacial catalysis. Various parameters such as catalyst precursor concentration, temperature, Rh/PTABS ratio, syngas pressure, CTAB concentration and volume of the aqueous phase were evaluated with 80oC, 25bar pressure for 1.5h being the optimized reaction conditions. This catalytic system could be recycled for up to three consecutive cycles.