Solvent free selective acetylation of veratrole over 12-tungstophosporic acid immobilized mesoporous silicates
12-Tungstophosporic acid (TPA, 10–50%) was successfully immobilized inside the mesopore channels of SBA-15 by wet impregnation method. The materials were characterized by powder X-ray diffraction, nitrogen adsorption isotherm and UV–Vis diffuse reflectance spectral techniques. The XRD showed well ordered hexagonal mesoporous structure for all the materials. Their catalytic activities were examined for the liquid phase acetylation of veratrole (1,2-dimethoxy benzene) with acetic anhydride. The 20% loaded TPA/SBA-15 showed higher activity than others. The product was 3,4-dimethoxy acetophenone with 100% selectivity. The exclusive formation of this product is ascribed to steric influence of methoxy substituents that prevent ortho substitution.
Journal: Catalysis Communications - Volume 9, Issue 5, 20 March 2008, Pages 594–599