Mild and highly selective hydrogenation of cyclohexyl acetate to cyclohexanol over Cu() coordinated amino-functionalized poly(ionic liquid)s

A novel, efficient and economical process of cyclohexanol (CHOL) production based on cyclohexene esterification-hydrogenation has become a research hotspot in recent years. Wherein, hydrogenation of cyclohexyl acetate (CHA) derived from the esterification of cyclohexene with acetic acid is a crucial step. Combining the advantages of metal complexes and heterogeneous catalysts, the robust Cu( i ) coordinated amino-functionalized poly(ionic liquid)s (PILs-Cu( i )) were, in this research, synthesized for use in the mild and highly selective hydrogenation of CHA to CHOL. The results of FT-IR, UV-vis, BET, XPS and SEM-EDS confirmed that the Cu( i ) was dominant in the PILs-Cu( i ), and was homogeneously and stably coordinated on the amino-functionalized poly(ionic liquid)s. Benefiting from that, the PILs-Cu( i ) was endowed with an unprecedented performance in the mild and highly selective hydrogenation of CHA to CHOL. Specifically, 95.6% CHA conversion with 96.6% selectivity of CHOL, and 97.0% selectivity of ethanol was obtained under extremely mild conditions of 80 °C and 2 MPa H 2 . Furthermore, no significant activity loss was observed over the PILs-Cu( i ) after recycling for at least five times, delivering excellent stability and reusability. Cu( i ) coordinated amino-functionalized poly(ionic liquid)s exhibited an unprecedented performance for mild and highly selective hydrogenation of esters.