METHOD OF PREPARING 2-METHYL-1,4-NAPHTHOQUINONE AND CATALYST FOR CARRYING IT OUT Russian patent published in 2001 - IPC

FIELD: fine organic synthesis, more particularly preparation of 2-methyl- 1,4-naphthoquinone (menadione). SUBSTANCE: method comprises catalytic oxidation of 2-methyl-1-naphthol or mixture thereof with 2,4-dimethyl-1-naphtanol in two phase system in which substance to be oxidized is reacted in water-immiscible organic solvent, preferably trichloroethylene, in the presence of catalyst which is essentially aqueous solution of molybdovanvadophosphoric heteropolyacid or acid salt thereof containing 10-20 vol % of acetic acid; oxidation reaction is carried out under vigorous agitation of phases at temperature from 40 to 70 C and general catalyst composition corresponds to formula: H_aP_xMo_yV_nO_b wherein n is number of vanadium atoms. Catalyst concentration is 0.2-0.3 M. Reaction uses molar ratio of heteropolyacid or acid salt thereof to methyl naphthol of not greater than 2.5. In order to regenerate catalyst, 0.05-0.1 ml of HNO₃ per 25 ml of heteropolyacid salt. Catalyst efficiency is by more than 60% higher than catalyst efficiency of prior art catalyst due to better selectivity and higher capacity of catalyst. Hydrogen peroxide need not be added in substrate oxidation stage. Amount of nitric acid added in catalyst regeneration stage is reduced by 3-4 times. EFFECT: more efficient method. 6 cl, 5 ex, 2 tbl