Effective synthesis of novel O-acetylated compounds over ZrO2-Al2O3 solid acid

Abstract

The solid acids such as ZrO2, Al2O3 and ZrO2-Al2O3 containing different ZrO2 loadings (10–80 mol%) were prepared by solution combustion method (SCM) and characterized for their total surface acidity by NH3-TPD/n-butylamine back titration method and crystallinity by powder X-ray diffraction (PXRD) technique. These solid acids were evaluated for their catalytic activity in the synthesis of novel O-acetylated products from substituted phenols, pyridine alcohols and aryl alcohols with acetic anhydride (AA) as an acetylating agent. The reaction conditions were optimized by varying the catalyst, molar ratio of the reactants, reaction temperature and amount of the catalyst. All the solid acids used in this study exhibited good catalytic activity in the reaction. In particular, ZrO2-Al2O3 containing 80 mol% of ZrO2 was found to be highly active in the acetylation reaction with high yield of acetylated products. Triangular correlation between the surface acidity, crystallinity and catalytic activity of solid acids was observed. These solid acids were found to be reactivable and reusable. Keywords: ZrO2-Al2O3, Solid acid, Solution combustion, Novel acetylated compounds, O-acetylation