K SERIES VITAMINS PRODUCTION METHOD Russian patent published in 2020 - IPC C07D213/81 C07C303/20 C07C303/32 C07C309/44 C07C46/04 C07C50/12 

FIELD: technological processes.

SUBSTANCE: present invention relates to a method for producing K₃ series vitamins, involving oxidation of starting 2-methylnaphthalene with compounds of hexavalent chromium in an acidic medium while heating to obtain 2-methyl-1,4-naphthoquinone (menadione) at the first step, reacting menadione with an aqueous solution of sodium bisulphite in a two-phase system consisting of an aqueous phase and an organic solvent with crystallization of sodium bisulfite menadione (MSB) at a second step, use of the mother solution after separating MSB or the solution without isolating MSB crystals in reaction with nicotinamide during acidification to obtain MNB at the third step. MNB obtained at the third stage is repulped in water and organic solvent with splitting into MSB and nicotinamide under action of alkaline agents at pH value in range of 4.5–7.0, then adding water-soluble aluminum compounds (in weight ratio of dry MNB and Al₂O₃ as 1:0.01–1) while maintaining pH of solution 4.0–5.0 with subsequent raising pH to 5.0–6.0, solution is filtered from insoluble particles and freshly precipitated aluminum hydroxide, the solution is acidified to pH 2.0–2.2, followed by sedimentation, filtration, washing and drying of the obtained MNB.

EFFECT: disclosed method enables to obtain menadione nicotinamide bisulphite (MNB) with high output and low content of chromium and organic impurities.

8 cl, 2 tbl, 4 ex