Preparation of alkyl levulinates from biomass-derived 5-(halomethyl) furfural (X = Cl, Br), furfuryl alcohol, and angelica lactone using silica-supported perchloric acid as a heterogeneous acid catalyst

This work reports the synthesis of a series of alkyl levulinates from biomass-derived 5-(halomethyl)furfural (X = Cl, Br), furfuryl alcohol, and angelica lactone using silica-supported perchloric acid (HClO4-SiO2) as a heterogeneous acid catalyst. The solvent-free, one-pot preparation afforded levulinate esters in excellent isolated yields (> 84%). The reactions were performed at 120 degrees C for 6 h in a batch-type glass pressure reactor using XMF and furfuryl alcohol in presence of excess of the alcohol reagent and 4 wt.% of the HClO4-SiO2 catalyst (0.028 mmol HClO4). Furthermore, the reaction protocol was extended for the synthesis of ALs starting with angelica lactone at 90 degrees C for 2 h in a round-bottomed flask by using excess alcohol and 4 wt.% of the HClO4-SiO2 catalyst.