Commercially available coal-based activated carbon was treated by nitric acid with different concentrations and the resultant samples were used as catalysts for the direct hydroxylation of benzene to phenol in acetonitrile. Boehm titration, X-ray photoelectron spectroscopy, scanning electron microscope coupled with an energy dispersive X-ray microanalyzer, and Brunauer-Emmett-Teller method were used to characterize the samples. The number of carboxyl groups on the surface was found to be the main factor affecting the catalytic activity. An optimum catalytic performance with a yield of 15.7% and a selectivity of 87.2% to phenol was obtained.
A new Fenton-like system in a medium of hydrophilic triethylammonium type of ionic liquid（IL） was used for the hydroxylation of benzene to phenol. The triethylammonium acetate（[Et3NH][CH3COO]） IL exhibited retardation performance for the decomposition of H2O2 and protection performance for the further oxidation of phenol, thus the yield and selectivity to phenol were promoted greatly. The acidity of the system was proved to be an important factor for the selectivity to phenol. The utilization of H2O2 and the selectivity to phenol, as well as the Turnover number（TON） of the catalyst were effectively enhanced by a benzene-[Et3NH][CH3COO] bi-phase system. The catalyst with [Et3NH][CH3COO] IL was recycled with stable catalytic performance.
HU Xiao-ke ZHU Liang-fang GUO Bin LIU Qiu-yuan LI Gui-ying HU Chang-wei
One-step anodic acetoxylation of benzene to phenyl acetate was studied in acetic acid-water solution using a one-compartment electrochemical cell in galvanostatic mode. Compared to the anhydrous system, the addition of water improved the current efficiency for the electrosynthesis of phenyl acetate. The maximum efficiency reached 4.8% with the selectivity of 96% to phenyl acetate when the electrolysis was carried out under the optimal conditions. The investigation also indicated that the concentration of phenyl acetate increased linearly in 12 h and reached 1.07 g/L with the selectivity of 95%. Cyclic voltammetry experiments showed that the adsorption of benzene at Pt anode enhanced by the addition of water was critical to the formation of phenyl acetate. An activated benzene mechanism was proposed for the anodic acytoxylation, and the analysis of gas products demonstrated that Kolbe reaction was the main side reaction.
