Activated charcoal grafted with phenyl imidazole groups for Knœvenagel condensation of furfural with malononitrile

Abstract Commercial activated charcoal Darco® KB-G with large specific area (1345 m2 g−1) was found to be an excellent carbonaceous support for chemical surface functionalization. Its covalent grafting with phenyl imidazole groups via diazonium chemistry was carried out under mild conditions (25 °C, Patm) by reacting 4-(1H-imidazol-1-yl)aniline with Darco in the presence of isopentyle nitrite as diazotization initiator. The success of the surface functionalization was evidenced by experimental XPS spectra and DFT calculations. The functionalized solid Darco-0.5IM with tertiary amine functions was well characterized and its catalytic activity was evaluated in the Knœvenagel condensation of furfural with malononitrile.