Pd(II) Ion Fixed on Sulfonated Polystyrene-Type Resin Catalysts for the Oxidation of 2-Methylnaphthalene to 2-Methyl-1, 4-naphthoquinone with Hydrogen Peroxide

Abstract

The oxidation of 2-methylnaphthalene to 2-methyl-1, 4-naphthoquinone (vitamin K₃) was carried out with aqueous (60%) H₂O₂ in acetic acid in the presence of Pd(II) salts at 50°C. The activities of Pd(II) salts were in the order of SO^2-₄>ClO^-₄>NO^-₃>AcO^->PO^3-₄>Cl^->Br^->I^-. The Pd(II) salts such as PdSO₄, Pd(ClO₄)₂, Pd(AcO)₂, and PdCl₂ were heterogenized by ion exchange between Pd(II) ion and protons of sulfonated polystyrene-type resin (SP resin) to give Pd(II)-SP resin. The use of 0.24% Pd(II)-SP resins gave a good yield (50 to 60%) of vitamin K₃ at 50°C. The catalyst could be recovered by filtration and reused conveniently.