Kinetics and mechanism of the oxidation of vanillic acid using smectite clay

In this study, the oxidation of vanillic acid (VA) into protocatechuic acid (PCA) was investigated using montmorillonite KSF as inexpensive and environmentally benign solid acid, with peroxide hydrogen to afford excellent yields (more than 75%) endowed with high selectivity. To our knowledge, the aforementioned method was used for the first time in green, clean synthesis. The influence of the several operating parameters were performed using an experimental design Box–Behnken methodology. The progress of the concentrations of VA and its oxidation product PCA was accomplished using ultra-high-performance liquid chromatography coupled to quadrupole-time-of-flight mass spectrometry (RP-UHPLC-DAD-QTOF-MS) and mass spectrometry. Accordingly, PCA would be advantageous when used in food as well as cosmetic and pharmaceutical industries. Finally, a mechanistic pathway for the VA oxidation was proposed.