Specific Enhancement of Catalytic Activity by a Dicopper Core: Selective Hydroxylation of Benzene to Phenol with Hydrogen Peroxide

A dicopper(II) complex, stabilized by the bis(tpa) ligand 1,2‐bis[2‐[bis(2‐pyridylmethyl)aminomethyl]‐6‐pyridyl]ethane (6‐hpa), [Cu 2 (μ‐OH)(6‐hpa)] 3+ , was synthesized and structurally characterized. This complex catalyzed selective hydroxylation of benzene to phenol using H 2 O 2 , thus attaining large turnover numbers (TONs) and high H 2 O 2 efficiency. The TON after 40 hours for the phenol production exceeded 12000 in MeCN at 50 °C under N 2 , the highest value reported for benzene hydroxylation with H 2 O 2 catalyzed by homogeneous complexes. At 22 % benzene conversion, phenol (95.2 %) and p ‐benzoquinone (4.8 %) were produced. The mechanism of H 2 O 2 activation and benzene hydroxylation is proposed.