Copper-cationic salphen catalysts for the oxidation of cyclohexene by oxygen
•Some new copper-salphen complexes with two cationic sites were prepared.•The types of counteranion in ionic compounds could affect the catalytic activity.•The catalyst activity can be controlled by changing the solvent polarity.
The modified copper-cationic salphen catalysts were synthesized and used in the allylic oxidation of cyclohexene to 2-cyclohexen-1-ol and 2-cyclohexen-1-one with oxygen under mild conditions. Compared with their unmodified counterpart, the catalytic activities of modified catalysts are improved. The type of counteranion could affect the reactivity of catalyst, which offers an opportunity to improve the catalysts via changing counteranions to optimize the selectivity. The cation–anion interaction can be adjusted by different solvents, which in turn influences the catalyst reactivity. Furthermore, these novel catalysts can be reused without sacrificing the activity.
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Journal: Catalysis Communications - Volume 59, 10 January 2015, Pages 97–100