Catalyst Combo For Cyclohexanone

Researchers at the Chinese Academy of Sciences’ Institute of Chemistry, in Beijing, have found that combining two common catalysts can produce the industrially important chemical intermediate cyclohexanone at higher yields and lower temperatures than do current methods (Science 2009, 326, 1250). Tao Jiang and colleagues used a palladium nanoparticle catalyst on a solid support and the Lewis acid catalyst AlCl₃ to hydrogenate phenol to cyclohexanone. The reaction, when carried out at 50 °C and 1 megapascal of H₂, proceeds with essentially 100% yield and selectivity. Cyclohexanone is the starting material used in the synthesis of materials such as nylon. Hydrogen­ating phenol via a palladium catalyst is a key industrial route to cyclohexanone, but it typically requires high temperatures (150–300 °C) and suffers from low yields. Scientists have searched for catalysts to improve the reaction, but they have had trouble preventing continued hydrogenation of cyclohexanone into cyclohexanol. Interactions between the Lewis acid and cyclohexanone might inhibit the excess hydrogenation into cyclohexanol.