Preparation of carbon nanotube-supported α-Fe2O3@CuO nanocomposite: a highly efficient and magnetically separable catalyst in cross-coupling of aryl halides with phenols

Abstract

Herein, we introduce the first magnetic CuO nanoparticles based on carbon nanotubes as a highly intriguing magnetic catalyst in Ullmann-type coupling of aryl halides with phenols. Two facile procedures were used for the preparation of this magnetically separable catalytic system. Having been treated with FeSO₄ and then H₂O₂, nanotubes accommodated the resulting iron hydroxides on the walls. The resulting nanocomposite was then exposed to argon atmosphere at 450 °C giving rise to a carbon nanotube-supported α-Fe₂O₃ compound. Ultimately, copper acetate was hydrolysed in the presence of CNT supported α-Fe₂O₃ at 100 °C and our novel catalyst was gained. Some spectroscopic and microscopic techniques such as Infrared spectroscopy (IR), X-ray diffraction spectroscopy (XRD), Vibrational sample magnetometry (VSM), Brunauer–Emmett–Teller (BET), Barrett–Joyner–Halenda (BJH), Inductively coupled plasma (ICP), Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) corroborated the structure of the catalyst. The catalyst synthesized showed good activity in C–O cross coupling reactions affording the highest rate of completion. Magnetic feature of the catalyst helped facile separation of it from the reaction medium. The catalyst could also be reused up to six times without any loss of its activity.