Microwave Assisted Sulfonation of 2-Naphthol by Sulfuric Acid: Cleaner Production of Schaeffer's Acid

Microwave (MW) assisted synthesis of Schaeffer's acid offers the advantage of efficient and rapid transformation of energy and heating throughout the volume and eliminates the use of excess solvent, sulfuric acid, during the course of reaction. The present study aims at assessing the conversion and selectivity for the production of Schaeffer's acid by sulfonation of 2-naphthol using microwave irradiation. Effects of operating parameters such as reaction time, feed composition, microwave energy, and reaction temperature were systematically investigated. Advantages like reduction in reaction time, reduced wastage of sulfuric acid in effluent, and increase in conversion along with enhanced selectivity were the chief observations. The kinetics of the system has also been studied.