Reduction of α,β-unsaturated aldehydes with basic MgO/M2O3 catalysts (M=Al, Ga, In)

An overall nine magnesium-aluminium, magnesium-gallium and magnesium-indium hydrotalcite-like compounds (HTlc) were obtained by coprecipitation, the sol-gel technique and precipitation with urea. A pure hydrotalcite phase was obtained in all instances; by exception, the indium products were a mixture of the corresponding HTlc and In(OH)(3). Products were characterized by X-ray diffraction (XRD) and their specific surface areas determined. Calcination in a nitrogen atmosphere at 500 degreesC yielded a peridase MgO phase-plus In2O3 from the products containing In(OH)(3). Calcined solids were characterized by XRD, and their specific surface areas and surface chemical properties determined (the latter by CO2 chemisorption). These solids were used as catalysts for the Meerwein-Ponndorf-Verley (MPV) reaction between traps-crotonaldehyde and isopropyl alcohol, and the one obtained by calcination of the Mg/Al HTlc prepared by coprecipitation-which was the most basic-was found to be the most active in the process. This catalyst was also tested on the MPV reduction of various alpha,p-unsaturated aldehydes with isopropyl alcohol. (C) 2003 Elsevier Science B.V. All rights reserved.