Hydroquinone

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A skin-lightening ingredient that works by inhibiting the activity of tyrosinase, by acting as a melanocyte cytotoxic inhibitor, and by increasing the cytotoxicity of melanocytes.

Hydroquinone (Wikipedia)
Hydroquinone
Hydroquinone
Trans-hydroquinone-from-xtal-3D-balls.png
Hydroquinone crystal.jpg
Names
IUPAC name
Benzene-1,4-diol
Other names
Idrochinone
Quinol/1-4 dihydroxy benzene/1-4 hydroxy benzene
Identifiers
123-31-9 YesY
ChEBI CHEBI:17594 YesY
ChEMBL ChEMBL537 YesY
ChemSpider 764 YesY
Jmol 3D image Interactive graph
KEGG D00073 YesY
RTECS number MX3500000
UNII XV74C1N1AE YesY
Properties
C6H6O2
Molar mass 110.11 g·mol−1
Appearance white solid
Density 1.3 g cm−3, solid
Melting point 172 °C (342 °F; 445 K)
Boiling point 287 °C (549 °F; 560 K)
5.9 g/100 mL (15 °C)
Vapor pressure 0.00001 mmHg (20°C)
Structure
1.4 D
Pharmacology
D11AX11 (WHO)
Hazards
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
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oilHealth code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroformReactivity (yellow): no hazard codeSpecial hazards (white): no codeNFPA 704 four-colored diamond
Flash point 165 °C (329 °F; 438 K)
Lethal dose or concentration (LD, LC):
490 mg/kg (mammal, oral)
245 mg/kg (mouse, oral)
200 mg/kg (rabbit, oral)
320 mg/kg (rat, oral)
550 mg/kg (guinea pig, oral)
200 mg/kg (dog, oral)
70 mg/kg (cat, oral)
US health exposure limits (NIOSH):
PEL (Permissible)
TWA 2 mg/m3
REL (Recommended)
C 2 mg/m3 [15-minute]
IDLH (Immediate danger)
50 mg/m3
Related compounds
Related benzenediols
Pyrocatechol
Resorcinol
Related compounds
1,4-benzoquinone
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Hydroquinone, also benzene-1,4-diol or quinol, is an aromatic organic compound that is a type of phenol, a derivative of benzene, having the chemical formula C6H4(OH)2. Its chemical structure, shown in the table at right, features two hydroxyl groups bonded to a benzene ring in a para position. It is a white granular solid. Substituted derivatives of this parent compound are also referred to as hydroquinones. The name "hydroquinone" was coined by Friedrich Wöhler in 1843.

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