1 DefinitionChEBI: A benzenediol comprising benzene core carrying two hydroxy substituents para to each other.

2 General DescriptionLight colored crystals or solutions. May irritate the skin, eyes and mucous membranes. Mildly toxic by ingestion or skin absorption.

3 Produe MethodThere are three current manufacturing processes for HQ:oxidative cleavage of diisopropylbenzene, oxidation of aniline,and hydroxylation of phenol.Diisopropylbenzene is air oxidized to the intermediatediisopropylbenzene bishydroperoxide. This hydroperoxideis purified by extraction and reacted further to formhydroquinone. The purified product is isolated by filtrationand packaged. The process can be almost entirely closed,continuous, computer-controlled, and monitored.HQcan also be prepared by oxidizing aniline to quinone inthe presence of manganese dioxide and sulfuric acid.p-Benzoquinone is then reduced to HQ using iron oxide.The resulting hydroquinone is crystallized and dried.The process occurs in a closed system.HQis also manufactured by hydroxylation of phenol usinghydrogen peroxide as a hydroxylation agent. The reaction iscatalyzed by strong mineral acids or ferrous or cobalt salts.

4 Purification MethodsCrystallise quinol from acetone, *benzene, EtOH, EtOH/*benzene, water or acetonitrile (25g in 30mL), preferably under nitrogen. Dry it under vacuum. [Wolfenden et al. J Am Chem Soc 109 463 1987, Beilstein 6 H 836, 6 IV 5712.] Hydroquinone Preparation Products And Raw materials Preparation Products

5 UsageUse as photographic reducer and developer; as reagent in the determination of small quantities of phosphate; as antioxidant. Depigmentor