Acid treated montmorillonite - efficient catalyst in Prins reaction of alpha-methylstyrene with paraldehyde

Abstract

Acid treated montmorillonite was used as a catalyst in Prins reaction of α methylstyrene with paraldehyde giving 2,4,6-trimethyl-4-phenyl-1,3-dioxane (Vertacetal). The product of this reaction is a bioactive compound, which can interact with GABA (gamma-aminobutyric acid) receptors and has fragrant properties. Montmorillonite (used for this reaction as catalyst) was prepared by treatment with hydrochloric, nitric, sulfuric or chloroacetic acid. The influence of acid used for treatment, and other reaction conditions (reaction temperature, solvent, reactant molar ratio, catalyst amount) on the reaction course were tested. Acid treated montmorillonite proved to be a catalyst suitable for this reaction – a high yield of desired product was obtained (>94%) at room temperature using different solvents. Solvent choice showed to be crucial for the reaction – the best results were obtained using nitromethane or 1,4-dioxane. The catalyst can be reused one time after calcination at 300 °C.