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 SO2-4>ClO-4>NO-3>AcO->PO3-4>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.
