Abstract: A new catalytic system, PdCl2/TSILs, for catalytic oxidation of styrene to acetophenone with hydrogen peroxide was designed through the combination of PdCl2 and task-specific ionic liquids (TSILs) of N-carboxyl-appended imidazolium cations with various anions. The PdCl2/TSILs catalytic system displayed excellent catalytic properties for the target reaction. The yield and selectivity of acetophenone depended critically on the TSILs structure with different combinations of carboxylic groups and counter-anions. The catalytic activity of PdCl2/TSILs was enhanced with the increase in the number of the carboxylic groups and the asymmetry degree of the cations. The activity of PdCl2/TSILs with the same cation also increased with the assorted anion sequence of PF-6

Key words: carboxyl, task-specific ionic liquid, palladium, styrene, selective catalytic oxidation, acetophenone, imidazolium cation