SÍNTESE DE PROPARGILAMINAS CATALISADA POR NANOPARTÍCULAS DE COBRE METÁLICO SUPORTADAS EM PASTILHAS DE VIDRO RECICLADO

Abstract

The development of greener, more efficient and attractively economical synthetic methodologies is one of the greatest challenges for the sustainable progress of organic synthesis. In recent years, considerable scientific effort has been made in search for more ecological catalysis that aim to minimize the generation of waste by using easily recyclable catalysts. Bearing in mind that glass is an accessible resource and an excellent matrix for the growth of metallic nanoparticles, this work involves the reuse of silica glass residues to obtain pellets and application as a heterogeneous support for the growth of metallic copper nanoparticles (Cu0 NPs) to use in catalysis. The glass residues were doped with Cu2O and then the Cu0 NPs were supported on the glassy matrix surface, under a reducing atmosphere of H2. The obtained material (Cu0 NPs@recycled glass pellet) was characterized by X-ray Diffraction (XRD), Laser-induced Breakdown Spectroscopy (LIBS), Energy Dispersive Spectroscopy (EDS) and Scanning Electron Microscopy (SEM) techniques, through which was possible to evidence the presence of metallic copper and the uniform distribution of the Cu0 NPs throughout the pellet surface. Next, the Cu0 NPs@recycled glass pellet was applied as a catalyst for the A3 -coupling reaction between aldehydes, amines and alkynes to obtain propargylamines, a class of nitrogenous compounds that has wide biologic and synthetic applications. The propargylamines were obtained under solvent-free conditions and the synthetic methodology developed proved to be efficient to obtain a wide variety of propargylamines with good to excellent yields (52 - 99%). Furthermore, the characteristic format, inherent to the proposed catalyst, allowed it to be easily recovered using simple tweezers and posteriorly reused for a minimum of 5 reaction cycles, without significant loss of catalytic activity. Overall, the solvent-free approach, the atom economy, recycling potential, sustainable character and the efficiency have made the Cu0 NPs@recycled glass pellet a promising catalyst for other organic transformations beyond the A3-coupling reaction.