Hydrogenation of (2E,4E)-hexadienol

Catalytic hydrogenation of (2E,4E)-hexadienol over Pt, Pd, Rh, Ru and Ni su pported on active carbon and gamma-alumina has been studied. In all the rea ctions, diverse isomers of alkenic hexenols were primarily produced, which further hydrogenated to hexanol. Various hexenals were identified in the re action mixture as well as hexanal, hexenes and hexane. The composition of t he reaction mixture depended foremost upon the type of a catalyst used and was independent on the hydrogen pressure and catalyst weight. A great numbe r of intermediates and products was produced over palladium, platinum and r hodium catalysts. These catalysts were not selective due to desired interme diates' production. Over ruthenium catalyst, (3E)-hexenol and (2E)-hexenol were produced in higher concentrations compared to the rest of the intermed iate products, and the least quantity of hexene and hexane were also produc ed. Regarding the production of various hexenols, the most selective cataly st was Raney nickel. When Ni/Al2O3 catalyst was used, hexenols were produce d in higher concentrations, but the selectivity was not higher than with Ra ney nickel. (C) 1999 Elsevier Science B.V. All rights reserved.