A facile synthesis of quinoxalines by using SO<sub>4</sub><sup>2−</sup>/ZrO<sub>2</sub>-TiO<sub>2</sub> as an efficient and recyclable heterogeneous catalyst
Sushil V. Shelke, Sambhaji T. Dhumal, Akshay Y. Karale, Tejshri R. Deshmukh, Meghshyam K. Patil
Abstract
Quinoxaline derivatives have been synthesized in good to excellent yields by the cyclocondensation reaction of o-pheneylenediamine with substituted phenacyl bromides/benzil in the presence of SO42−/ZrO2-TiO2 as an efficient and heterogeneous catalyst. The catalyst can be recovered up to five catalytic cycles without significant loss in catalytic activity. The reported SO42−/ZrO2-TiO2 catalyst has been thoroughly characterized by using infrared spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and powder X-ray diffraction (XRD). Here, we have used ethanol as a green solvent in this cyclocondensation. This new method has several advantages, such as excellent yields, short reaction time, nontoxic, and easily recoverable catalyst.