Metal free: A novel and efficient aerobic oxidation of toluene derivatives catalyzed by N′, N″, N‴, -trihydroxyisocyanuric acid and dimethylglyoxime in PEG-1000-based dicationic acidic ionic liquid

A non-metal catalytic system containing of N′, N″, N‴, -trihydroxyisocyanuric acid (THICA) and dimethylglyoxime (DMG) is described for the selective oxidation of toluene derivatives with dioxygen in PEG-1000-based dicationic acidic ionic liquid (PEG1000–DAIL). Several toluene derivatives were efficiently oxidized to corresponding acids under mild conditions. The oxidation followed a radical pathway and a possible mechanism was proposed. Both the catalyst and PEG1000–DAIL could be reused at least eight times without significantly decreasing the catalytic activity.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► THICA-DMG was used in the oxidation of toluene-substituted derivatives. ► Ionic liquid PEG1000 –DAIL was used as solvent. ► A possible mechanism of this catalytic process was proposed. ► The catalyst could be reused at least eight times.