Sulfination of acetanilide using liquid coordination complexes as dual catalyst and solvent

Abstract The Freidel-Crafts sulfination reaction of acetanilide with sulfur dioxide was catalyzed by several AlCl 3 -based liquid coordination complexes (LCCs), and the results were compared with that catalyzed by traditional ILs. Influences of different catalysts, ligand/AlCl 3 molar ratios, and reaction conditions on their catalytic performance were investigated. The optimal result was obtained using acetamide-AlCl 3 -based LCC (molar ratio of acetamide to AlCl 3 was 0.65, marked as 0.65 A A/AlCl 3 ) as the catalyst, giving nearly 100% conversion of acetanilide within 60 min and 94.07% of selectivity to 4-acetamidobenzenesulfinic acid. AA/AlBr 3 was synthesized and also showed catalytic activity for the sulfination reaction. Then a plausible reaction mechanism was proposed by investigation through the raman spectra.