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 ?
This same regimen administered through the studies is available via participating dermatologists and physicians that prescribe or sell the Obagi Nu-Derm System, which includes a cleanser, toner, exfoliation enhancer (Exfoderm and Exfoderm Forte), four percent hydroquinone product (Nu-Derm Clear and Nu-Derm Blender), Sunscreen SPF 35 (Healthy Skin Protection SPF 35) and, if recommended by the prescribing physician, tretinoin cream.
If new pigment control products were able to generate fast, effective results without the use of hydroquinone, the pigment control market would experience tremendous growth," says Kevin Flewwelling, Manager of the Aesthetics division at MRG.
Studies show that Lumixyl, a chain of ten amino acids, promoted the moderation of melanin more efficaciously than hydroquinone.
The history of Obagi's skin care product introductions is as follows: Obagi Nu-Derm[R], 1988; Obagi-C[R] Rx (the first and only prescription-strength vitamin C and hydroquinone system), 2004; Obagi[R] Professional-C (a line of highly stable vitamin C serums), 2005; Obagi[R] Condition and Enhance for use with cosmetic procedures to enhance patient outcomes and satisfaction, 2006; Obagi ELASTIderm[TM] eye treatment and Obagi CLENZIderm[R] M.
It is the researchers' hypothesis that prodrugs yielding hydroquinone ansamycins intracellularly may be effective Hsp90 inhibitors.
While these OTC creams are effective for mild forms of melasma, a dermatologist may prescribe creams with higher concentrations of hydroquinone.
By bringing Glyquin(R) to the market, ICN is providing treatment of hyperpigmentation with the combination of hydroquinone and glycolic acid in a prescription bleach that does not contain the known allergy producer sodium metabisulfite.
Obagi launched its first skincare system, Obagi Nu-Derm, in 1988; and in 2004 launched the first and only prescription strength Vitamin C and hydroquinone system, Obagi-C Rx.
Over 66% used medicated soaps which they claimed were very good on their skin, but 17% of these cosmetics contain hydroquinone while 14% and 35% of the soaps contain potassium mercuric iodide.
The book Toxics A to Z: A Guide to Everyday Pollution Hazards describes how one film chemical, hydroquinone, has been known to cause eye and skin irritation.
Then, to add insult to injury, a number of these benzene metabolites (primarily phenol, hydroquinone, catechol, and trans-trans muconic acid) actually intensify the chemical's toxic effect on an organ.