Hydroquinone


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hydroquinone

[¦hī·drə·kwə′nōn]
(organic chemistry)
C6H4(OH)2 White crystals melting at 170°C and boiling at 285°C; soluble in alcohol, ether, and water; used in photographic dye chemicals, in medicine, as an antioxidant and inhibitor, and in paints, varnishes, and motor fuels and oils. Also known as hydrochinone; hydroquinol; quinol.

Hydroquinone

 

(also called p-dihydroxy-benzene), colorless crystals. Melting point, 170.3° C; density, 1.358 g/cm3. Sublimates in a vacuum.

Hydroquinone is readily soluble in ethanol and ether and slightly soluble in benzene; 5.7 g of hydroquinone dissolves in 100 g of water at 15° C. It is a powerful reducing agent. In aqueous solutions, particularly alkaline solutions, it is oxidized by atmospheric oxygen.

p-benzoquinone

Hydroquinone is produced industrially by the reduction of quinone, as well as by alkaline fusion of p -hydroxy-benzenesulfonic acid or p -chlorophenol.

Hydroquinone is used as a photographic developer and as an antioxidant. It is an intermediate in the synthesis of many organic dyes. In analytical chemistry it is used in the determination of a number of elements. The molecular compound of hydroquinone with quinone—so-called quinhydrone, C6H4O2 C6H4(OH)2—is used in determining hydrogen-ion concentration. The compound of hydroquinone with glucose, arbutin, is widespread in nature. Hydroquinone was first prepared by the German chemist F. Wöhler in 1844.

References in periodicals archive ?
He added that these cases are an act of deception and misguidance including the video which featured the Hydroquinone cream for skin whitening.
Oral tranexamic acid 500 mg had a better response when compared with topical hydroquinone 2% cream and better safety profile.
Dermatologists in the United States can prescribe creams or lotions containing up to 4% hydroquinone for patients with skin conditions.
In April last year, trading standards in Newham, East London, reported that hydroquinone made up 8.
While the incidence of PIH is lower with nonablative fractional resurfacing, compared with ablative resurfacing, PIH can still occur whether pretreatment hydroquinone is used or not.
A number of traditionally used skin lightening ingredients, including hydroquinone, are prohibited in skin lightening cosmetic products due to adverse effects on health.
Key words: Iron (III) kojic acid complex Hydroquinone L-Cysteine Reduction.
The court was told he had already served a fourmonth sentence after mercury and illegal chemical hydroquinone were discovered in cosmetics, back in July 2009.
Historically the treatment of melasma has been challenging and the various modalities of treatment include broad spectrum sunscreens, hydroquinone in various concentration, tretinoin, fluorinated steroids, kojic acid, salicylic acid, glycolic acid, azelaic acid, lactic acid, chemical peels, laser therapy like Q switched ruby, alexandrite, Nd; YAG laser etc.
Hydroquinone has some carcinogenic (cancer causing) effects when applied to skin.
Obagi has also come up with a better alternative to hydroquinone," said Kho.
Common topical agents include hydroquinone, retinoids, azelaic acid, kojic acid, lignin peroxidase, and various botanical agents.