Synthesis, characterization, and catalytic application of biocompatible chitosan-graphene oxide aerogel in the retro-aza-Henry-type conversion

Abstract

In this study, graphene oxide-chitosan aerogel (GO-CS) with honeycomb structure was prepared using sol-gel and freeze-drying methods. The physicochemical properties of nanocatalyst were investigated by FTIR, TGA, BET, XRD, RAMAN, FESEM-EDS, and elemental mapping to support that cross-linking occurs between the –COOH groups of GO and amine groups of CS and examine the surface properties and porosity of the prepared material. The prepared aerogel material showed appropriate thermal stability, interesting honeycomb-like structure, high porosity, surface functional group versatility, and high surface area, which all of them are the desired properties for catalytic purposes. In continuation, the catalytic activity of the prepared GO-CS has been evaluated in the reaction between β-nitrostyrene derivatives and hydrazine hydrate (N₂H₄.H₂O) in the ethanol as a solvent. Using only 0.3 w% of this aerogel material as a catalyst, the reactions for all 20 derivatives of β-nitrostyrenes were completed in 3 h at 50 °C in almost quantitative yields (98–100 %). The employed catalyst showed high reusability experiments and after six consecutive runs, the reaction remained quantitative.