METHOD OF OBTAINING VITAMINS OF K SERIES 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 vitamins of the K₃ series, involving the oxidation of 2-methylnaphthalene with hexavalent chromium compounds in an acidic medium with heating to produce 2-methyl-1,4-naphthoquinone (menadione). When this oxidation is carried out at 48–55 °C, the resulting menadione is transferred to menadione sodium bisulfite (MSB), the synthesized MSB is subjected to primary crystallization, and then isohydric recrystallization in an aqueous solution in the temperature range of 80–0 °C, with the subsequent return of the mother liquor from the primary crystallization to the treatment of nicotinamide in an acidic environment with obtaining menadione nicotinamide bisulfite (MNB) or to the MSB synthesis stage, and the mother liquor from recrystallization to the MSB dissolution stage.

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

3 cl, 4 ex