Yield-efficient process for the production of highly pure 2-methyl-1,4-naphthoquinone and its derivatives

摘要

The present invention concerns a process for the production of 2-methyl-1,4-naphthoquinone and its derivatives, comprising the following steps:a) oxidizing 2-methyl-naphthalene (2-MNA) to achieve an organic phase containing 2-methyl-naphthoquinone (2-MNQ) and 6-methyl-naphthoquinone (6-MNQ);b) subjecting said organic phase to treatment with an aqueous solution of a bisulfite salt to extract preferentially the 6-MNQ isomer from the organic phase;c) separating said organic phase from the aqueous phase:d) optionally removing interfering bisulfite ions from said aqueous phasee) raising the pH of said aqueous phase to higher than 8.5 in the presence of a solvent resulting in an organic phase containing 2-MNQ;f) isolating said 2-MNQ from said organic phase.