Rational Designed Polymer as a Metal-Free Catalyst for Hydroxylation of Benzene to Phenol with Dioxygen

Abstract Direct hydroxylation of benzene to phenol with dioxygen is a green route for synthesis of phenol. The higher bonding energies of C–H in benzene and O–O in dioxygen make metal-free catalysis a challenge. A novel metal-free catalyst of quinone-cylcohexanone-formaldehyde polymer was rationally designed and prepared. The polymer was characterized with FT-IR, XRD, Raman, SEM, 13 C NMR and XPS. Abundant oxygen functional groups of cyclic ketonic, quinone carbonyl and hydroquinone were found on the surface of polymer. The catalytic performances for hydroxylation of benzene to phenol with dioxygen over the metal-free catalyst were investigated and a phenol yielding of 11.4% was achieved. Moreover, the reaction mechanism was proposed. Graphic Abstract