Infrared investigation of chemisorption of cyclohexanol and cyclohexanone on Pt/SiO2

Adsorption of cyclohexanol on PtSiO2 catalyst was investigated by means of ir spectroscopy. At room temperature hydrogen atoms from both OH and tertiary carbons split off easily, resulting in the formation of cyclohexanone held on SiO2 by hydrogen bonds whereas on Pt it is held by a π-bond or through the lone electron pair of oxygen. Dissociation of α-hydrogens in cyclohexanone commences only at circa 353 K. At 393 K bands characteristic of an enolic system were observed, suggesting formation of a π-oxoallylic species during dehydrogenation of cyclohexanone.