Product Profile 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. There are a variety of other uses associated with its reducing power. As a polymerization inhibitor, hydroquinone prevents polymerization of acrylic acid, methyl methacrylate, cyanoacrylate, and other monomers that are susceptible to radical-initiated polymerization. This application exploits the antioxidant properties of hydroquinone Applications Hydroquinone has a variety of uses principally associated with its action as a reducing agent which is soluble in water. • It is a major component in most photographic developers for film and paper where, with the compound Metol, it reduces silver halides to elemental silver. • Hydroquinone, is used mainly as a polymerization inhibitor, as an antioxidant ingredient for rubbers, and as a pigment. • Hydroquinone is used as a developing agent in black and white photography, lithography, and x-ray films. • About 0.05% of the hydroquinone manufactured is used in skin lightening creams. • Hydroquinone is also used as a coupler in oxidative hair dyes Production Process Hydroquinone is produced industrially by three routes, two of which are dominant. Similar to the cumene process in reaction mechanism, the most widely used route involves the dialkylation of benzene with propene to give 1,4-diisopropylbenzene. This compound reacts with air to afford the bis(hydroperoxide), which is structurally similar to cumene hydroperoxide and rearranges to give acetone and hydroquininone in acid. A second route involves hydroxylation of phenol. The conversion uses hydrogen peroxide and affords a mixture of hydroquinone and catechol: C6H5OH + H2O2 ? C6H4(OH)2 + H2O The third method, practiced only in China, is the oxidation of aniline by manganese dioxide followed by reduction of the resulting 1,4-benzoquinone. The process is conducted batchwise and generates a substantial waste stream. Market scenario The global demand for hydroquinone is driven by high, sustained growth of certain markets such as superabsorbent polymers, paint, construction, automotive or electronics. The market was extremely tight during 2010–2011; additional capacity scheduled for commissioning in 2012 will alleviate the market tightness temporarily during 2012–2014. However, the hydroquinone market is expected to become tight again in 2014–2016, unless new capacity would be announced Hydroquinone is sold by manufacturers as a dry, crystalline solid packaged in plastic film lined sacks or drums.
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