(NHPI)-oxime (DMG) catalyst system had better performance in the PEG 1000-based functional dicationic acidic liquid (PRG-DALL) then in the conventional organic solvents for the aerobic oxidation of ethylbenzene and its derivatives.
PEG-DALL enhanced the ability of NHPI: 91.9% conversion of ethylbenzene with 84.8% selectively for acetophenone could be obtained in 7 h, and 92.1% ethylbenzene was oxidized to benzonic acid with 89.3% selectively in 12 h. Ethylbenzenes with electron-rich groups were oxidized to different products when time was changed, but the main product was only ketone when electron-withdrawing ethylbenzene was employed. Both the catalyst and PEG-DALL could be reused at least six times without significantly decreasing the catalytic activity.