TRANSFORMATIONS OF CYCLOHEXANE DERIVATIVES IN SUPERCRITICAL WATER

Functional group transformations in supercritical water were examined for a series of cyclohexane derivatives including cyclohexane, cyclohe xene, cyclohexanol, cyclohexanone, benzene, and phenol. No reactions w ere observed in the absence of a catalyst, but hydration-dehydration, skeletal isomerization, and hydrogenation-dehydrogenation transformati ons did occur in the presence of an acid, base, or metal catalyst. Deh ydrogenations included the ketonization of cyclohexanol and the aromat ization of cyclohexanone, cyclohexene, and cyclohexane. The dehydrogen ations required a late transition metal catalyst (e.g. PtO2 or 10% Pt/ C) and proceeded even in the absence of a sacrificial hydrogen accepto r. Cyclohexanol dehydration was catalyzed by either acid or base, whil e cyclohexene hydration was only observed in reactions involving both PtO2 and an acid or base. Skeletal isomerization was an acid-catalyzed process. These reactions demonstrate that organic functional group tr ansformations in supercritical water can be accessed through the selec tion of appropriate catalysts.