Revealing efficient catalytic performance of N-CuO_x for aerobic oxidative coupling of aliphatic alkynes: A Langmuir–Hinshelwood reaction mechanism

Oxidative couplings of aliphatic alkynes are crucial for the production of naturally occurring 1,3-diynes. Herein we report the novel approach for effective synthesis of unsaturated coordinated N doped copper oxides (N-CuO_x) catalyst, and uncover that N-CuO_x catalyst as an additive-free and cost-effective heterogeneous catalyst has highly catalytic performance for directly oxidative coupling of aliphatic alkynes. The key to achieve efficient oxidative coupling of aliphatic alkynes is the synergistic effect of N species and uncoordinated O/Cu species caused by N dopants, which undergoes the Langmuir–Hinshelwood reaction mechanism. The N-CuO_x catalyst displays ~ 89.1% yield for hexadeca-7,9-diyne under mild conditions and stable reusability (5 cycles), showing significant advances compared with the traditionally copper oxides. These findings highlight the heteroatom dopants that provide a new methodology for designing efficient copper catalysts in synthesis of naturally occurring 1,3-diynes.