New routes to vitamin K3

New clean and efficient methods for the production of 2-methyl-1,4-naphthoquinone (MNQ, menadione, Vitamin K3) based on the oxidation of 2-methyl-1-naphthol (MNL) with cheap and environmentally benign oxidants, aqueous hydrogen peroxide, tert-butyl hydroperoxide and molecular oxygen, using three types of true heterogeneous catalysts, such as hydrothermally stable mesoporous titanium-silicate Ti-MMM-2, silica supported iron phthalocyanine and supported gold nanoparticles, are reported. Advantages and drawbacks of the catalytic systems are discussed. Surprisingly, non-catalytic oxidation of MNL with molecular oxygen shows superior selectivity and volume yield of MNQ compared to the known catalytic methods.