Efficient Gold–Palladium Nanoparticles Stabilized by Poly(amic acid) Salt: Synthesis and Application in Catalytic Oxidation of Amines to Imines

Copper-supported thiol-functionalized cellulose as a paper-based catalyst for imine synthesis

This study presents an appealing approach to sustainable catalysis using cellulose filter paper as a support for copper-catalyzed reactions. The paper was functionalized with thiol groups through a reaction with thioglycolic acid, which served a dual purpose: partially reducing Cu(II) to Cu(I) and stabilizing active copper species via Cu-S interactions. Spectroscopic analysis confirmed the formation of highly dispersed multi-valent Cu2O/CuO on the thiol-functionalized cellulose, resulting in a highly efficient copper catalyst. This catalyst demonstrated excellent performance in the oxidative coupling of various amines to imines, achieving yields of 39-99% within 10-30 min. A key advantage of this system is its reusability; the catalyst maintained remarkable stability and activity over ten reaction cycles with straightforward recovery. This paper-based catalyst offers a promising strategy for eco-friendly and cost-effective synthetic processes, with significant implications for green chemistry and industrial applications.

Excellent Catalytic Performances of a Au/C-CuO Binary System in the Selective Oxidation of Benzylamines to Imines under Atmospheric Oxygen

A green method of the oxidation of benzylamines to imines was developed using a novel binary system of Au/C-CuO. This system was evaluated under atmospheric oxygen, and the corresponding imines were obtained in up to 100% yields by loading 0.006 mol % of Au/C and 1.25 mol % of CuO under mild conditions. This system was also successfully applied to the syntheses of N-containing functional molecules, as well as that of imines on the scale of several grams. Furthermore, the turnover number of the system (more than 8000 times on a gold basis) as well as its ability to be reused more than 10 times for benzylamine oxidation demonstrates the excellent durability and recyclability of the developed system.