Quantitative formation of gamma-valerolactone from furfural aldehyde with a recyclable acidic system and Ru-MACHO catalyst under a H2 atmosphere

Abstract

This study presents an efficient catalytic system for the direct conversion of carbohydrate derived furfural aldehyde (FA) into γ valerolactone (GVL) in excellent yields. Using a homogeneous Ru MACHO BH catalyst in combination with a recyclable solid acid as co catalyst, GVL is obtained in up to 99% NMR yield under hydrogenative conditions (120 °C, 30 bar H₂, 24 h, ethanol). Full conversion and exclusive selectivity toward GVL are achieved with 0.5 mol% Ru MACHO BH and 5 mol% Amberlyst 36. The solid acid co catalyst can be reused for at least ten cycles following a simple regeneration of the Amberlyst-36 with H2SO4(aq) between runs, representing an important step toward improving the overall sustainability of the process by reducing waste generation and material input, while also enhancing its economic viability. The robustness of the method was evaluated through scale up experiments up to 20 mmol (1.9 g) of FA. At this scale, conversions of 65–72% were observed with 0.5 mol% Ru MACHO BH, maintaining 100% selectivity to GVL, whereas increasing the catalyst loading to 1 mol% restored full conversion and quantitative GVL formation. Overall, this work demonstrates a selective and scalable approach to FA valorization under well defined reaction conditions.