Selective Synthesis of Unsaturated Alcohols over Heterogeneous Metal-Ion Catalysts

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Mesoporous silicate, MCM-41 was synthesized by using hexadecyl trimethyl ammonium bromide as a template. MCM-41, SiO_2, Al_2O_3, TiO_2 and some zeolites were impregnated with some kinds of tin and zirconium salts. The catalyst were calcined and reduced at prescribed temperatures.The selective reductions of crotonaldehyde and acctophenone were carried out with a secondary alcohol in stainless steel autoclave (30 ml).Hydrogenation of crotonaldehyde over metallic catalysts produces significant amount of butyraldehyde and 1-butanol, corresponding hydrogenates of C=C doublc bond. The addition of Sn was effective to improve the selectivity of crotyl alcohol, corresponding hydrogenate of carbonyl group over metallic catalysts. The supported Sn and Zr catalysts indicated that carbonyl groups were selectivcly reduced via hydrogen transfer reaction from secondary alcohol added as a solvent (MPV reduction). The effects of support and starting salts were investigated. Silica including MCM-41 was suitable for the support of Sn and Zr. Acidic or basic support was not effective. Zirconium supported on active carbon was also highly active. Neutral porous materials should be selected for the supports. Tin acetate for Sn catalysts and zirconium oxychloride for Zr catalysts were ones of the best starting salts, respectively Dependence of reduction temperature on the yicld of unsaturated alcohol indicated that Sn (II) and Zr (IV) were active species for the selective reduction of carbonyl compounds. Enatiomeric-excess of S-1-phenyl ethanol was improved by the addition of cinconidine in the reation mixture.