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hydroquinone

 
Dictionary: hy·dro·qui·none   (hī'drō-kwĭ-nōn', -kwĭn'ōn') pronunciation also hy·dro·quin·ol
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(-kwĭn'ôl', -ōl')
n.
A white crystalline compound, C6H4(OH)2, used as a photographic developer, an antioxidant, a stabilizer, and a reagent.


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Chemistry Dictionary: benzene-1,4-diol
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Variant: hydroquinone; quinol

A white crystalline solid, C6H4(OH)2; r.d. 1.33; m.p. 170°C; b.p. 285°C. It is used in making dyes. See also quinhydrone electrode.


Dental Dictionary: hydroquinone
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(hīdrō-kwin'ōn)
n

1. a reducing agent used as an inhibitor in resin monomers to prevent polymerization during storage. n 2. one of the two chemicals used as reducing agents in film-developing solutions. Hydroquinone is made from benzene (paradihydroxyben-zene) and is sensitive to thermal changes. Above 70° F (21° C), the action of hydroquinone is rapid; below 60° F (15.5° C), hydroquinone becomes inactive. Its action is to control the contrast of the film.

Drug Info: Hydroquinone
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Brand names: Aclaro PD™, Aclaro™, Alera™, Alphaquin™ HP, Alustra™, Claripel™ with Sunscreens, Complex B™, Eldopaque Forte®, Eldopaque®, Eldoquin Forte®, EpiQuin™ Micro, Esoterica®, Esoterica® Sensitive Skin, Esoterica® with Sunscreen, Essential™ Care Skin Bleaching Cream, Essential™ Care Skin Bleaching Cream with Sunscreen, Glyquin®, Glyquin.XM™, Glytone™, HQ Plus AHA™, HQ Plus Bearberry™, HQ™ Cream with Sunscreens, Hydroquinone, Lustra®, Lustra-AF®, Melanex®, Melpaque® HP, Melquin® 3, Melquin® HP, Nava-SC™, Nuquin® HP, Opticell™ AM PM Cream, Palmers™ Skin Success, Skin Bleaching Gel™, Solaquin Forte®, Solaquin®

Chemical formula:



Hydroquinone Topical cream

What is this medicine?

HYDROQUINONE is applied to the the skin to lighten areas that have darkened. Some products also contain sunscreens.

This medicine may be used for other purposes; ask your health care provider or pharmacist if you have questions.

What should I tell my health care provider before I take this medicine?

They need to know if you have any of these conditions:
• an unusual or allergic reaction to hydroquinone, sunscreens, other medicines, foods, dyes, or preservatives
• pregnant or trying to get pregnant
• breast-feeding

How should I use this medicine?

This medicine is for external use only. Do not take by mouth. Follow the directions on the prescription label. Wash your hands before and after applying. Make sure the skin is clean and dry. Apply just enough to cover the affected area. Rub in gently but completely. Do not apply near the eyes, mouth, or other areas of sensitive skin. If accidental contact occurs, large amounts of water should be used to wash the affected area. If the eyes are involved and eye irritation persists after thoroughly washing, contact your doctor. If you are using other skin medicines, apply them at different times of the day. Do not use your medicine more often than directed.

Talk to your pediatrician regarding the use of this medicine in children. Special care may be needed.

Overdosage: If you think you have taken too much of this medicine contact a poison control center or emergency room at once.
NOTE: This medicine is only for you. Do not share this medicine with others.

What if I miss a dose?

If you miss a dose, take it as soon as you can. If it is almost time for your next dose, take only that dose. Do not take double or extra doses.

What may interact with this medicine?

• benzoyl peroxide

This list may not describe all possible interactions. Give your health care provider a list of all the medicines, herbs, non-prescription drugs, or dietary supplements you use. Also tell them if you smoke, drink alcohol, or use illegal drugs. Some items may interact with your medicine.

What should I watch for while using this medicine?

Contact your doctor or health care professional if your condition does not improve in the first two months or if you experience too much skin irritation.

This medicine will work best if you avoid excessive exposure to sunlight and wear sunscreens and protective clothing. Some hydroquinone products contain sunscreens. Use a sunscreen (SPF 15 or higher). Do not use sun lamps or sun tanning beds or booths. Do not apply to sunburned areas or if you have a skin wound in the area of application.

Most cosmetics, sunscreens, and moisturizing lotions may be worn over this medicine. Wait several minutes after application of this medicine before applying them.

What side effects may I notice from receiving this medicine?

Side effects that you should report to your doctor immediately:
• severe burning, itching, crusting, or swelling of the treated areas
• unusual skin discoloration

Side effects that usually do not require medical attention (report to your doctor if they continue or are bothersome):
• mild itching or stinging
• reddening of the skin

This list may not describe all possible side effects. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Where should I keep my medicine?

Keep out of the reach of children.

Store at room temperature between 15 and 30 degrees C (59 and 86 degrees F). Do not freeze. Throw away any unused medicine after the expiration date.

Last updated: 7/1/2002

Important Disclaimer: The drug information provided here is for educational purposes only. It is intended to supplement, not substitute for, the diagnosis, treatment and advice of a medical professional. This drug information does not cover all possible uses, precautions, side effects and interactions. It should not be construed to indicate that this or any drug is safe for you. Consult your medical professional for guidance before using any prescription or over the counter drugs.

Veterinary Dictionary: hydroquinone
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Thought at one time to be the toxic component of Xanthium spp., a now discredited view.

Wikipedia: Hydroquinone
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Hydroquinone
Hydroquinone
Trans-hydroquinone-from-xtal-3D-balls.png
IUPAC name
Other names Idrochinone
Quinol
Benzene-1,4-diol
Identifiers
CAS number 123-31-9 Yes check.svgY
RTECS number MX3500000
SMILES
Properties
Molecular formula C6H4(OH)2
Molar mass 110.1 g/mol
Appearance white solid
Density 1.3 g/cm3, solid
Melting point

172 °C, 445 K, 342 °F
Boiling point

287 °C, 560 K, 549 °F
Solubility in water 5.9 g/100 ml (15 °C)
Structure
Dipole moment zero
Hazards
EU classification Harmful (Xn)
Carc. Cat. 3
Muta. Cat. 3
Dangerous for
the environment (N)
R-phrases R22 R40 R41 R43 R50 R68
S-phrases (S2) S26 S36/37/39 S61
NFPA 704
NFPA 704.svg
1
2
0
 
Flash point 165 °C
Related compounds
Related benzenediols Pyrocatechol
Resorcinol
Related compounds 1,4-benzoquinone
 Yes check.svgY (what is this?)  (verify)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Hydroquinone, also benzene-1,4-diol or quinol, is an aromatic organic compound which is a type of phenol, having the chemical formula C6H4(OH)2. Its chemical structure, shown in the table at right, has two hydroxyl groups bonded to a benzene ring in a para position. It is a white granular solid at room temperature and pressure.

Contents

Nomenclature

Hydroquinone is the name recommended by the International Union of Pure and Applied Chemistry (IUPAC) in its 1993 Recommendations for the Nomenclature of Organic Chemistry [1]

Properties

Hydroquinone can undergo mild oxidation to convert to benzoquinone. Reduction of quinone reverses this reaction back to hydroquinone. Some biochemical compounds in nature have this sort of hydroquinone or quinone section in their structures, such as coenzyme Q, and can undergo similar redox interconversions.

The hydroxyl groups of hydroquinone are quite weakly acidic. Hydroquinone can lose an H+ from one of the hydroxyls to form a monophenolate ion or lose an H+ from both to form a diphenolate ion.

Uses

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 where, with the compound metol, it reduces silver halides to elemental silver.

In human medicine, hydroquinone is used as a topical application in skin whitening to reduce the color of skin as it does not have the same predisposition to cause dermatitis as metal does. There is inadequate evidence in humans for the carcinogenicity of hydroquinone.[2] This use is banned in some countries, including the member states of the European Union under Directive 76/768/EEC:1976.[3][4]

The disodium diphenolate salt of hydroquinone is used as an alternating comonomer unit in the production of the polymer PEEK.

As a polymerization inhibitor, hydroquinone prevents polymerization of acrylic acid, methyl methacrylate, etc.

It is also used as a raw material of herbicides, rubber antioxidants, and dyestuffs.

Natural occurrences

Hydroquinones are one of the two primary reagents in the defensive glands of bombardier beetles, along with hydrogen peroxide (and perhaps other chemicals, depending on the species), which collect in a reservoir. The reservoir opens through a muscle-controlled valve onto a thick-walled reaction chamber. This chamber is lined with cells that secrete catalases and peroxidases. When the contents of the reservoir are forced into the reaction chamber, the catalases and peroxidases rapidly break down the hydrogen peroxide and catalyze the oxidation of the hydroquinones into p-quinones. These reactions release free oxygen and generate enough heat to bring the mixture to the boiling point and vaporize about a fifth of it, producing a hot spray from the beetle's abdomen.

Farnesyl hydroquinone derivatives are the principal irritants exuded by the poodle-dog bush, which can cause severe contact dermatitis in humans.

See also

References

  1. ^ Panico, R.; & Powell, W. H. (Eds.) (1994). A Guide to IUPAC Nomenclature of Organic Compounds 1993. Oxford: Blackwell Science. ISBN 0-632-03488-2. 
  2. ^ IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Volume 71, Re-Evaluation of Some Organic Chemicals, Hydrazine and Hydrogen Peroxide]
  3. ^ 76/768/EEC:1976 Council Directive 76/768/EEC of 27 July 1976 on the approximation of the laws of the Member States relating to cosmetic products : http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:31976L0768:EN:HTML
  4. ^ Example of a product recall in Ireland

External links

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This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

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Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.  Read more
Chemistry Dictionary. A Dictionary of Chemistry. Sixth Edition. Copyright © Market House Books Ltd, 2008. All rights reserved.  Read more
Dental Dictionary. Mosby's Dental Dictionary. Copyright © 2004 by Elsevier, Inc. All rights reserved.  Read more
Drug Info. Gold Standard. Copyright © 2008 by Gold Standard. All rights reserved.  Read more
Veterinary Dictionary. Saunders Comprehensive Veterinary Dictionary 3rd Edition. Copyright © 2007 by D.C. Blood, V.P. Studdert and C.C. Gay, Elsevier. All rights reserved.  Read more
Wikipedia. This article is licensed under the Creative Commons Attribution/Share-Alike License. It uses material from the Wikipedia article "Hydroquinone".  Read more