A Recyclable Solid Acid Catalyst Sulfated Titania for Easy Synthesis of Quinoxaline and Dipyridophenazine Derivatives under Microwave Irradiation

Abstract

Abstract TiO2–SO42−, prepared by sol–gel method has been used for the synthesis of quinoxaline and dipyridophenizine derivatives under microwave irradiation. High-resolution transmission electron microscope (HR-TEM) and atomic force microscope (AFM) images reveal the corrosion of TiO2 particles by sulfuric acid, which causes an increase in the acidity of the catalyst. Sulfate loading by H2SO4 increases catalytic activity of TiO2. This catalyst gives an excellent yield with less reaction time and is an inexpensive, easily recyclable and efficient catalyst for this reaction.