Pinacol-Pinacolone rearrangement over solids supported metal ion catalysts

Abstract

Catalytic activity of hydrated Al₂O₃, SiO₂, ZrO₂,AlPO₄, zeolite-HY and Fe(III) ions supported on these solids has been evaluated in pinacol-pinacolone rearrangement (2,3-dimethyl-2,3-butanediol to 3,3-dimethyl-2-butanone). The effect of method of preparation of catalysts on their catalytic activity has been evaluated. Studies on catalytic activity have been performed in vapour phase at different reaction temperatures. Pinacolone and 2,3-dimethyl-1,3-butadiene were formed as the major products. The percentage conversion of pinacol and the selectivity of the products have been found to be influenced by the reaction temperature, the nature of the support, the metal ion present on the support and the method of preparation of supported catalysts. Al₂O₃ and AlPO₄ containing 5% Fe ions on their surface are found to convert pinacol to pinacolone to an extent of 88% with a selectivity of 83% for ketone at 200 °C with 10 mL/h flow rate of the reactant. A comparative study of the catalytic activity of the materials containing 5% Fe ions on Al₂O₃ and those containing same percentage of Ni or Co ions in the chosen reaction at 200 °C, revealed a good correlation between the redox potential of the metal ions and their selective catalytic activity in the formation of pinacolone.