Lewis acid metal cations exchanged heteropoly salts as catalysts in β-pinene etherification

In this work, the protons of the Keggin heteropolyacids were exchanged by Lewis acid metal cations generating salts that were evaluated as catalysts on the beta-pinene etherification with alkyl alcohols. The Fe(III) phosphotungstate salt (i.e. FePW12O40) was the most active and selective catalyst toward the formation of alpha-terpinyl methyl ether, the main reaction product. The activity of FePW(12)O(40)catalyst was higher than their precursors of synthesis (i.e. H3PW12O40, Fe(NO3)(3)), other Fe(III) heteropoly salts (i.e. FePMo(12)O(40)and Fe4/3SiW12O40), and heteropoly salts of different Lewis acids (i.e. AlPW12O40, Cu-3(PW12O40)(2)). The effects of the main variables of reaction such as temperature, catalyst load, and alcohol nature were assessed. The Fe(III) cation, as well as the phosphotungstate anion, showed to be essential to the formation of the goal-product (alpha-terpinyl alkyl ether). [GRAPHICS] .