Zr Oxo Cluster for Cascade Conversion of Furfural to Alkyl Levulinates

Abstract A novel dodecanuclear Zr oxo cluster [Zr 6 O 4 (OH) 4 (HSCH 2 CH 2 COO) 12 ] 2 (ZrO‐SH‐10) has been constructed under the room temperature, followed by oxidation of the sulfhydryl group with H 2 O 2 to achieve a bifunctional catalyst with Lewis acid and Brönsted acid sites. The characterization of catalysts indicated that {Zr 6 O 4 } cluster core can be stabilized with a shell of carboxylate ligands, and the resulting ZrO‐SO 3 H was formed as a discrete molecular catalyst, exhibiting superior activity and recyclability for the cascade conversion of furfural to alkyl levulinate by the integration of transfer hydrogenation and alcoholysis in n‐butanol. The yield of n‐butyl levulinate can achieve as high as 91 % under the optimum conditions. Meanwhile, no leaching of the active species was found, which confirmed the structure of the Zr oxo cluster was air and moisture‐stable. On the basis of the studies on the reaction kinetics and isotope tracking, the reaction mechanism was proposed accordingly.