Patent ID: 8071817

Claim:
A process for the preparation of purified hydroquinone in the form of flakes, from a crude hydroquinone essentially comprising hydroquinone and small amounts of impurities, including at least resorcinol, pyrogallol and traces of pyrocatechol, which comprises the following stages: a stage of purification of the crude hydroquinone by distillation, comprising: (A) a topping distillation, in which the crude hydroquinone HQ 0 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; (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; and a stage of forming the purified hydroquinone obtained at the distillation outlet, by deposition of the latter as a film on a support made of a thermally conductive material or coated with a thermally conductive material, followed by the solidification thereof by adjusting the support to an appropriate temperature, then recovering the solidified hydroquinone in the form of flakes.