Hydroquinone

"Hydroquinone, also benzene-1,4-diol or quinol, is an aromatic organic compound that is a type of phenol, having the chemical formula C₆H₄(OH)₂. Its chemical structure, shown in the table at right, features two hydroxyl groups bonded to a benzene ring in a para position. It is a white granularsolid. Substituted derivatives of this parent compound are also referred to as hydroquinones."

"In term of the reactivity of its O-H groups, hydroquinone resembles other phenols, being weakly acidic. The resulting conjugate base undergoes easy O-alkylation to give mono- and diethers. Similarly, hydroquinone is highly susceptible to ring substitution by Friedel-Crafts reactions such as alkylation. This reaction is exploited en route to popular antioxidants such as 2-tert-butyl-4-methoxyphenol ("BHA"). The useful dye quinizarin is produced by diacylation of hydroquinone with phthalic anhydride."