Green synthesis of copper nanoparticles using Plantago asiatica leaf extract and their application for the cyanation of aldehydes using K4Fe(CN)6

[Display omitted] •Green synthesis of the Cu NPs using aqueous extract of the leaves of Plantago asiatica.•Cu NPs was characterized by FT-IR, UV–Vis, TEM, X-ray diffraction.•Cu NPs exhibited good catalytic activity in cyanation of aldehydes in the extract as a green solvent.•This catalyst could be easily recovered and reused several times. Copper nanoparticles (Cu NPs) were synthesized via a green method by using of Plantago asiatica leaf extract as natural solvent and reaction biomedia under environmentally benign reaction conditions. It was observed that use of Plantago asiatica leaf extract makes a simple, eco-friendly and cost effective method for the preparation of the Cu NPs and can reduce copper ions into Cu(0) within 5min of reaction time without using any stabilizer or surfactant agent. The progress of the reaction was monitored using UV–Visible spectroscopy. Polyphenolics could be adsorbed on the surface of Cu NPs, possibly by interaction through π-electrons interaction in the absence of other strong ligating agents. The catalytic activity of the Cu NPs was evaluated by cyanation of aldehydes in the extract as a green solvent. This method provided several advantages such as cleaner easy work-up, shorter reaction time and higher yield. Cu NPs were characterized by FT-IR, UV–Vis, TEM, X-ray diffraction and the synthesized products were characterized by FT-IR and 1H NMR.