Catalytic activity of tetravalent metal phosphates and phosphonates on the oxidation of (+)-3-carene

Tetravalent metal phosphates and phosphonates form highly insoluble inorganic polymers and can act as good catalysts in some oxidative reactions. In the present work, zirconium phosphate amorphous (ZrPA), scandium exchanged zirconium phosphate amorphous (ScZrPA), sodium exchanged zirconium phosphate amorphous (NaZrPA), potassium exchanged zirconium phosphate amorphous (KZrPA), zirconium phenylphosphonate amorphous (ZrPPA) and zirconium phenylphosphonate phosphate amorphous (ZrPA/ZrPPA), were prepared and evaluated as catalysts for the oxidation of 3,7,7-trimethylbicyclo[4.1.0]hept-3-ene [(+)-3-carene)] by hydrogen peroxide, in different solvents. It was found that the oxidation reaction of (+)-3-carene yielded three major products, namely alpha-3,4-epoxycarane, carane-3 beta,4 alpha-diol and 3 beta-acetoxycaran-4 alpha-ol, depending on the catalyst and solvent conditions. No beta-3,4-epoxycarane was detected in the studied conditions. (C) 2008 Elsevier B.V. All rights reserved.