Tungstic Acid: A Simple and Effective Solid Catalyst in Terpene Alcohol Oxidation Reactions with Hydrogen Peroxide

In this work, we report for the first time, the tungstic acid-catalyzed oxidation of terpene alcohols with hydrogen peroxide. This simple, solid, and commercially available catalyst efficiently promoted the conversion of borneol, geraniol and nerol to camphor and epoxide products, respectively. Effects of main reaction parameters, such as catalyst load, the molar ratio of oxidant to the substrate, time, and reaction temperature were investigated. Conversions and selectivity greater than 90% were achieved using 1.0 mol % of H2WO4 after 2 h of reaction at 90 degrees C. The activation energy was equal to 66 kJmol(-1). We propose a reaction mechanism based on the experimental results. This solid catalyst was easily recovered and reused without loss of activity. As far as we know, it is the first time that tungstic acid was used as the catalyst in the oxidation reactions of terpene alcohols. [GRAPHICS] .

Automated summary

In this study, tungstic acid was used as a catalyst for the oxidation of terpene alcohols with hydrogen peroxide for the first time. The catalyst, which is simple, solid, and commercially available, efficiently converted borneol, geraniol, and nerol to camphor and epoxide products. Various reaction parameters were investigated, and conversions and selectivity greater than 90% were achieved using 1.0 mol% of H2WO4 after 2 hours of reaction at 90 degrees C. The catalyst could be easily recovered and reused without loss of activity. This is the first time that tungstic acid has been used as a catalyst for the oxidation reactions of terpene alcohols.