Chapter 4 - Applications of heteropoly acids as homogeneous catalysts

Abstract

In this chapter, a number of applications of heteropoly acids are discussed. Heteropoly acids could be used as a homogeneous catalyst in many different reactions like oxidation, multicomponent reactions, and synthesis of heterocyclic compounds. From the reported results, it is identified that heteropoly acids are efficient, green, reusable, and inexpensive catalysts, and their use has been increasingly growing. In addition to catalytic applications in organic synthesis, they have intriguing applications in photochemistry. From a technological point of view, heteropoly acids may be appropriately used instead of traditional acid catalysts such as ion exchange resins, mineral acids, or zeolites in both homogeneous and heterogeneous catalytic processes. It is important to note that their use in homogeneous systems is not an obstacle to reuse. Heteropoly acids are extensively soluble in polar solvents, but they are not soluble in nonpolar solvents such as hydrocarbons. Therefore, heteropoly acids can be recovered from a polar organic solvent by precipitation using a nonpolar solvent without any neutralization.