Nanostructured Carbon Catalyst for Amide Coupling Reactions under Microwave Heating in the Absence of a Solvent

Carbon nanostructures offer a perfect link between nanoscale materials and organic molecules, making them an ideal platform for molecular catalysts. Herein, an efficient, straightforward, and high-yield synthetic approach is described to synthesize aryl boronic acid containing the pyrene moiety that is noncovalently immobilized by pi-pi interaction to carbon nano-onions' surface. The nanostructured carbon material catalyzes the direct amide coupling reaction under microwaved heating in the absence of a solvent. The multilayered structures of carbon nano-onions ensure high thermal stability, and simultaneously, they are excellent microwaved absorbers, which reduce energy consumption. The absorption of microwaved radiation by the nanostructured carbon catalyst effectively influences yield of the catalytic reaction, which is up to 94%. Additionally, the recovery of catalytic material is straightforward, and the mass losses are negligible. Microwave heating in a solvent-free condition simplifies the reaction and reduces the amount of waste, which, in turn, depletes the environmental impact.

Automated summary

Carbon nanostructures provide an ideal platform for molecular catalysts, and the noncovalent immobilization of aryl boronic acid on carbon nano-onions' surface through pi-pi interaction is achieved in this study. The nanostructured carbon material acts as a catalyst for the direct amide coupling reaction under microwaved heating without a solvent. The high thermal stability and microwave absorption properties of carbon nano-onions contribute to the high catalytic yield of up to 94%. The straightforward recovery process and minimal mass losses make this synthesis method environmentally friendly.