Flower-like Bi2O2CO3-mediated selective oxidative coupling processes of amines under visible light irradiation

The photocatalytic selective transformation of amines is a green and cost-effective technology to obtain value-added products in chemical industry. In this work, a series of bismuth-based photocatalysts including Bi 2 MoO 6 , Bi 2 WO 6 , Bi 5 O 7 Cl, Bi 5 O 7 Br, Bi 5 O 7 I, BiPO 4 , BiVO 4 , Bi 2 O 3 and various morphology Bi 2 O 2 CO 3 (flower-like, sponge-like, plate-like and spherical) were synthesized and employed in the aerobic oxidative coupling of benzylamine. It is found that flower-like Bi 2 O 2 CO 3 exhibited the highest photocatalytic activity, in which a 100% conversion of benzylamine with 99.0% selectivity of N -benzylidenebenzylamine was obtained at room temperature. Moreover, the photocatalytic oxidative coupling processes of various aromatic and aliphatic amines were further investigated, and excellent yields and selectivities of corresponding products are attained. Then, based on characterization results (XRD, SEM, BET and XPS, etc.) of catalyst, high photocatalytic activity of flower-like Bi 2 O 2 CO 3 is attributed to thin nanopetals, low band gap, the morphology and large specific surface area. Finally, a possible reaction mechanism is proposed for the photocatalytic oxidative coupling of benzyl amine.