Silica–sulfuric acid and alumina–sulfuric acid: versatile supported Brønsted acid catalysts

Abstract

–SO₃H functionalized silica and alumina have emerged as efficient and eco-compatible heterogeneous solid acid catalysts for the construction of various important molecular skeletons. The advantages of –SO₃H functionalized silica and alumina from the standpoint of sustainability are attributed to their thermal stability, easy recovery, and efficient recyclability without a significant loss of their catalytic activity. With the objective to minimize the formation of waste and to maximize the use of renewable resources, numerous protocols have been developed around the globe to replace the conventional homogeneous acidic catalysts by SO₃H-functionalized silica and alumina. This comprehensive review deals with an overview of the utilization of silica–sulfuric acid and alumina–sulfuric acid as heterogeneous supported Brønsted acid catalysts for important organic transformations with a focus toward the syntheses of different industrially appealing as well as pharmaceutically important compounds.