One-pot synthesis of C8 aldehydes/alcohols from propylene using eco-friendly hydrotalcite supported HRhCO(PPh3)3 catalyst

Abstract

A multi-functional catalyst [HF/HT] containing a rhodium complex, HRh(CO)(PPh3)3 [HF] and a solid base, hydrotalcite Mg1−xAlx(OH2)x+(CO32−)x/n·mH2O [HT], synthesized by impregnation of [HF] onto the surface of [HT], was investigated for the one-pot synthesis of C8 aldol derivatives (aldehydes or alcohols) from propylene. The catalyst was found to be efficient to carry out hydroformylation, aldol condensation and hydrogenation reactions in one pot. The catalytic activity of [HF/HT(X)] was studied in detail as functions of Mg/Al molar ratio (X) of [HT], amount of [HF] complex and [HT], and reaction temperature. The selectivity for 2-ethylhexanal was observed to increase upon increasing X and amount of [HT]. The highest selectivity for 2-ethylhexanol was observed for [HT] Mg/Al molar ratio of 3.5 at 250 °C. The kinetic profiles of the various products obtained were in agreement with the reaction pathway proposed to understand the role of the [HF/HT] catalyst on the formation of C8 aldol derivatives. Thermal stability of the [HF/HT] catalyst system was also investigated.