Improved photocatalytic performance for selective oxidation of amines to imines on graphitic carbon nitride/bismuth
Aili Yuan1, Hua Lei1, Zhongsen Wang1
1Department of Chemistry, Zhejiang Sci-Tech University, 928 Second Avenue, Xiasha Higher Education Zone, Hangzhou 310018, China.
Abstract:
Imine compounds are vital intermediates in organic synthesis, and their cost-effective and green preparation has inspired numerous interests. Herein, we employ an environmentally friendly photocatalysis strategy to selectively oxidize amines to obtain imines. The heterojunction photocatalysts of graphitic carbon nitride/bismuth tungstate (CN/BW) were fabricated by hydrothermal growth of bismuth tungstate on the surface of graphitic carbon nitride. Characterization results demonstrate that the composites have been well composited and show improved separation ability of photo-generated charge carriers due to the formed type II band alignment. In comparison to the individual CN and BW, the heterojunctions exhibit apparent enhanced activity for the selective oxidation of amines to imines using O2 as the oxidant under irradiation of visible light. The optimized CN/BW heterojuntion with 75% BW content presents the high conversion (~98%) and selectivity (~98%) in 3 h oxidative coupling reaction of benzylamine. Furthermore, this heterojunction photocatalyst also has excellent cycling stability, as well as good catalytic performance for various benzylamine derivatives. On the basis of experimental results, the transfer pathway of photo-excited electrons and holes in the heterojunction photocatalyst was illustrated and a possible mechanism for the subsequent selective oxidation of amines to imines was proposed. This work provides an economical, sustainable and thus green process for the amine transformation.
More Related Videos
Related Concept Videos
Preparation of Amines: Reduction of Oximes and Nitro Compounds
Though catalytic hydrogenation can reduce nitrobenzenes, the reduction is nonselective in the presence of other functional groups. For instance, if nitrobenzene contains an aldehyde group,...
Preparation of Amines: Reductive Amination of Aldehydes and Ketones
Aldehydes and Ketones with Amines: Imine Formation Mechanism
Imines are formed under mildly acidic conditions. A pH of 4.5 is ideal for the reaction.
If the pH is low or the solution is too acidic, the reaction slows down in the...
Preparation of Amines: Reduction of Amides and Nitriles
Amides can be reduced to primary, secondary, and tertiary amines using catalytic hydrogenation, active metals like Fe,...
Aldehydes and Ketones with Amines: Imine and Enamine Formation Overview
Amines to Amides: Acylation of Amines
Next, the second equivalent of amine serves as a Brønsted base and deprotonates the quaternary...


