METHOD OF EXTRACTING AND PURIFYING HYDROQUINONE FROM CRUDE MIXTURES Russian patent published in 2012 - IPC C07C37/74 C07C46/10 C07C39/08 

FIELD: chemistry.

SUBSTANCE: invention relates to a method of purifying crude hydroquinone HQ⁰, essentially containing hydroquinone and small amounts of impurities, containing both: (i) impurities having a lower evaporation temperature than that of hydroquinone, referred to as light impurities, including resorcinol; and (ii) impurities having a higher evaporation temperature than that of hydroquinone, referred to as heavy impurities, including pyrogallol. Said method is characterised by that is includes the following steps: (A) distillation in the top part of the column, in which the crude hydroquinone HQ⁰ is injected into a distillation column, having reflux ratio from 300 to 2000, and where the resorcinol is removed in the top part of the column, optionally in conjunction with all or part of the other light impurities, whereby a crude mixture M, containing hydroquinone and heavy impurities, is recovered in the bottom part of the column; and (B) distillation in the bottom part of the column, in which the crude mixture M obtained in step (A) is injected into the distillation column and where pyrogallol is removed in the bottom part of the column, optionally in conjunction with all or part of the other heavy impurities, whereby hydroquinone in purified form (HQ), having impurity content less than 4000 ppm, is recovered in the top part of the column.

EFFECT: invention is a cost-effective method for purifying hydroquinone.

18 cl, 1 ex, 2 dwg