Mild and highly selective hydrogenation of cyclohexyl acetate to cyclohexanol over Cu(i) 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 degrees 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.

Automated summary

A novel process of cyclohexanol production based on cyclohexene esterification-hydrogenation using Cu(i) coordinated amino-functionalized poly(ionic liquid)s (PILs-Cu(i)) as catalysts has been developed. The PILs-Cu(i) exhibited excellent performance in the mild and highly selective hydrogenation of cyclohexyl acetate (CHA) to cyclohexanol (CHOL), achieving high conversion and selectivity. The catalyst also showed good stability and reusability after multiple recycling.