Catalytic hydrogenolysis of aromatic ketones in mixed choline-betainium ionic liquids.
The palladium-catalyzed hydrogenolysis of aromatic ketones to alkylbenzenes was studied in mixtures of ionic liquids to explore the promotional effect of these reaction media. Choline-based ionic liquids displayed complete miscibility with the aromatic ketone substrate at reaction temperature and a clear phase separation of the derived alkylbenzene product at room temperature. Selected ionic liquids were then assessed as reaction media in the hydrogenolysis of aromatic ketones over palladium catalysts. A binary mixture of choline and betainium bis(trifluoromethylsulfonyl)imide ionic liquids resulted in the highest conversion and selectivity values in the hydrogenolysis of acetophenone. At the end of the reaction, the immiscible alkylbenzene separates from the ionic liquid mixture and the pure product phase can be isolated by simple decantation. After optimization of the reaction conditions, high yields (>90 %) of alkylbenzene were obtained in all cases. The catalyst and the ionic liquid could be used at least three times without any loss of activity or selectivity.
Van Doorslaer
Charlie
C
Department of Microbial and Molecular Systems, KU Leuven, Centre for Surface Chemistry and Catalysis, Kasteelpark Arenberg 23, 3001 Leuven, Belgium.
Wahlen
Joos
J
Mertens
Pascal G N
PG
Thijs
Ben
B
Nockemann
Peter
P
Binnemans
Koen
K
De Vos
Dirk E
DE
D001554:Benzene / Q000737:chemistry; D001622:Betaine / Q000031:analogs & derivatives* / Q000737:chemistry; D002384:Catalysis; D002794:Choline / Q000737:chemistry*; D045424:Complex Mixtures / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D052578:Ionic Liquids / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry*; D010165:Palladium / Q000737:chemistry
D045424:Complex Mixtures; D052578:Ionic Liquids; D007659:Ketones; D001622:Betaine; D010165:Palladium; D006859:Hydrogen; D001554:Benzene; D002794:Choline