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(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.



(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.


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 ?
"Hydroquinone, without the supervision of a doctor, could lead to severe consequences and disfigurement.
Several analytical methods have been reported for the determination of arbutin and/or hydroquinone including high-performance liquid chromatography (HPLC), gas chromatography-mass spectrometry (GC-MS), capillary zone electrophoresis, and densitometry.
Conclusion: The combination of 4% hydroquinone with 10% mandelic acid is more effective in melasma as compared to conventional topical treatment.
She added: "There's no doubt that you knew what your obligations were and you should not have been marketing products which contained banned substances, especially hydroquinone. "I'm quite satisfied you knew exactly what you were selling and sourced them for the people who wanted to buy them from you."
Hydroquinone, banned in the UK in 2001, causes skin damage and is linked to damage of the liver and nervous system.
Dubai [United Arab Emirates], Apr 15 ( ANI ): Three skin whitening creams have been banned by the health authorities here for containing the harmful ingredient - Hydroquinone.
On the other hand, hydroquinone and tretinoin are classified as drugs in the country due to their harmful effects to the body.
ZO Medical by Zein Obagi MD Melanin Skin Bleaching and Correcting Creme Hydroquinone USP 4%
Banaras Hussain was caught selling cosmetics at his shop in Rye Lane, Peckham, that contained illegal levels of hydroquinone and corticosteroids, which can cause cancer and irreversible skin damage.
In a post on Instagram, the department of health and safety of the Dubai Municipality said the cream contains hydroquinone, which is found in prescription drugs, along with mercury, which has a toxic effect on humans.
Common therapeutic approaches for melasma include topical hydroquinone (HQ), azelaic acid, steroids, chemical peels, and lasers, most of which could not induce remarkable and constant satisfying outcomes [2, 3, 7].
Catechol (1,2-dihydroxybenze, CT) and hydroquinone (1,4-dihydroxybenze, HQ) are two dihydroxybenzene isomers that occur naturally in many plant foods (onions, coffee, tea leaves, etc.) and beverages such as wines [1].