Azide-Assisted Growth of Copper Nanostructures and Their Application as a Carbon Supported Catalyst in Two-Step Three-Component Azide-Alkyne Cycloadditions

Copper nanostructures were obtained from the reductionof Cu(I)under mild conditions in ethanol/water using sodium-l-ascorbateand sodium azide while performing an amination reaction. When thehalobenzene substrate was reacted in the presence of a bulk carbonblack (CB) support, clustered copper sub-micrometer particles (SMPs)and microparticles (MPs) form. The growth conditions of the MPs wereoptimized, and the supported nanostructures were isolated and characterizedby scanning electron microscopy, energy dispersive X-ray spectroscopy,thermogravimetry, and inductively-coupled plasma mass spectrometry.The particles are mobile and supported within the CB matrix and provedto be active catalysts in the azide-alkyne cycloaddition (CuAAC).The catalytic competency of the particles was assessed in a two-stepthree-component azide-alkyne cycloaddition of benzyl bromide,sodium azide, and phenylacetylene as a model reaction. The reactionconditions were optimized, and the optimized conditions were appliedfor the synthesis of triazole compounds with varying levels of functionalization.The recyclability of the catalysts was investigated, depletion modeswere discussed, and the conditions were fine-tuned to reach good recyclability.This demonstrates the broader applicability of the SMPs/MPs as CuAAC-catalystand its limitations.

Automated summary

Copper nanostructures were obtained by reducing Cu(I) under mild conditions in ethanol/water using sodium-l-ascorbate and sodium azide in an amination reaction. When reacting the halobenzene substrate in the presence of a bulk carbon black support, clustered copper sub-micrometer particles (SMPs) and microparticles (MPs) were formed. The supported nanostructures were characterized and found to be active catalysts in the azide-alkyne cycloaddition (CuAAC). The catalytic competency of the particles was assessed and optimized conditions were used for the synthesis of triazole compounds.