Keggin Heteropolyacid Salt Catalysts in Oxidation Reactions: A Review

Keggin heteropolyacids (HPAs) are metal–oxygen clusters with strong Bronsted acidity. The conversion of HPAs to metal salts can result in Lewis acidity, improving their performance oxidation reactions. In this review, the main routes for synthesis Keggin-type salts, as well use catalysts processes a plethora substrates, such monoterpenes, olefins, aldehydes, terpene alcohols, and aromatics, described. Green reactants hydrogen peroxide molecular oxygen used oxidants. These reactions interest several industries because they be produce drugs, additives, fragrances, fine chemicals. high efficiency HPA green oxidants contributes reduction environmental impact these processes, preconize principles chemistry. Moreover, converted bifunctional by modification structure, total or partial replacement protons acid cations, introduction cations into anion replacing addenda atoms (i.e., W Mo). Aspects linked characterization discussed herein, emphasis on infrared spectroscopy powder XRD patterns. most recent advances achieved development catalytic systems based also addressed.