Microwave-Assisted One Pot Cascade Conversion of Furfural to γ-Valerolactone over Sc(OTf)₃

γ-Valerolactone (GVL) is considered as a star biochemical which can be used as a green solvent, fuel additive and versatile organic intermediate. In this study, metal triflate (M(OTf)_n ) was utilized as the catalyst for one-pot transformation of furfural (FF) to GVL in alcohol media under microwave irradiation. Alcohol plays multiple functions including solvent, hydrogen donor and alcoholysis reagent in this cascade reaction process. And process efficiency of GVL production from FF upgrading is strongly related to the effective charge density of selected catalyst and the reduction potential of selected alcohol. Complex (OTf)_n -M-O(H)R, presenting both Brønsted acid and Lewis acid, is the real catalytic active species in this cascade reaction process. Among various catalysts, Sc(OTf)₃ exhibited the best catalytic activity for GVL production. Various reaction parameters including the Sc(OTf)₃ amount, reaction temperature and time were optimized by the response surface methodology with the central composite design (RSM-CCD). Up to 81.2 % GVL yield and 100 % FF conversion were achieved at 143.9 °C after 8.1 h in the presence of 0.16 mmol catalyst. This catalyst exhibits high reusability and can be regenerated by oxidative degradation of humins. In addition, a plausible cascade reaction network was proposed based on the distribution of product.