Solid Sulfonic Acid-Promoted Oxidation of Benzyl Alcohol Catalyzed by Isoamyl Nitrite

Isoamyl nitrite was employed to catalyze the selective oxidation of benzyl alcohol to benzyl aldehyde using molecular oxygen, in which solid sulfonic acid was used to promote the in situ generation of nitrosonium cation. Solid acid prepared by treating Amberlyst 15 at 300 degrees C demonstrated the best promotion effect, with which 90% conversion and 97% selectivity for benzyl aldehyde could be achieved at 80 degrees C under 0.5 MPa for 2 h. The differences of solid acids and their influence on oxidation were investigated by Fourier transform infrared spectroscopy, derivative thermogravimetry, and acid-base titration. Nitrosonium cation was detected by the derivative method using ultraviolet-visible absorption spectrometry.