Separation and purification of hydroquinone from crude mixtures thereof

A process for the purification of a crude hydroquinone HQ0 essentially comprising hydroquinone and small amounts of impurities, including 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,
• the said process which comprises the following stages:
• (A) a topping distillation, in which the crude hydroquinone HQ0 is injected into a distillation column and where the resorcinol is removed as distillation top product, optionally in conjunction with all or part of the other light impurities, whereby a crude mixture M, comprising hydroquinone and the heavy impurities, is recovered at the column bottom;
• and
• (B) a tailing distillation, in which the crude mixture M obtained in stage (A) is injected into a distillation column and where the pyrogallol is removed at the column bottom, optionally in conjunction with all or part of the other heavy impurities, whereby hydroquinone in a purified form (HQ) is recovered at the column top.