Hydration of α-Pinene over Heteropoly Acid H3PW12O40 and H3PMo12O40

Abstract

Heteropoliacid acid was used as catalyst for the hydration of α-pinene using water as hydroxyl donor. Since the selectivity of desired products is influenced by the reaction conditions, in this paper we study the behavior of phosphotungstic acid (HPW) and phopholmolibdic acid (HPMo) catalysts in homogeneous system under different experimental conditions (inert or oxidizing atmosphere, different ratio water/α-pinene, partial neutralization of the HPW and HPMo to optimize the production of terpene alcohols. When operating in inert atmosphere without agitation, the HPMo is more active than the HPW and by increasing time increases the concentration of α-terpineol. When the catalyst used is HPW products are mainly low molecular weight, while if HPMo is used, preferably the products have high molecular weight. A decrease in the amount of water increases the conversion of α-pinene. When the reaction occurs in equimolar ratio water/α-pinene, using HPMo catalyst, 100% conversion is achieved in 24 hr. The partial neutralization of the acid sites with aluminum, reduces the conversion of α-pinene due to a decrease in Brönsted acidity and production of α-terpineol increases possibly caused by the Lewis acidity is increased.