METHOD OF PRODUCING K3 SERIES VITAMINS Russian patent published in 2019 - IPC C07C303/20 C07C303/32 C07C309/44 C07D213/81 C07C46/04 C07C50/12 

FIELD: chemistry.

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, reaction of menadione with an aqueous solution of sodium bisulphite in a two-phase system consisting of an aqueous phase and an organic solvent with crystallisation of menadione sodium bisulfite (MSB) at a second step, using a mother solution after separation of MSB in reaction with nicotinamide in acidification to obtain menadione nicotinamide bisulphite (MNB) at the third stage. At the second step, menadione is specified in weight ratio with water-immiscible organic solvent as 1:1–10 (in dry menadione) and water to obtain a MSB solution of not more than 21 wt. %, acidifying the obtained solution to pH = 2.0–2.5, followed by separation for at least 30 minutes without stirring and separating the aqueous and organic phases, evaporating the aqueous phase under vacuum of 0.95 MPa at temperature of 40 °C and recovery of MSB crystals, regeneration of organic solvent from upper organic layer.

EFFECT: proposed method allows to obtain final products with a minimum chromium content.

4 cl, 4 ex