ContaminantDB: Hydroquinone

Identification Taxonomy Biological Properties Physical Properties Toxicity Profile Spectra Concentrations Links References Targets (15)XML

Record Information

Version

1.0

Creation Date

2014-09-05 17:10:15 UTC

Update Date

2026-05-14 19:06:26 UTC

Accession Number

CHEM003537

Identification

Common Name

Hydroquinone

Class

Small Molecule

Description

Hydroquinone, also benzene-1,4-diol, is an aromatic organic compound which is a type of phenol. Hydroquinone is commonly used as a biomarker for benzene exposure. The presence of hydroquinone in normal individuals stems mainly from direct dietary ingestion, catabolism of tyrosine and other substrates by gut bacteria, ingestion of arbutin containing foods, cigarette smoking, and the use of some over-the-counter medicines. In human medicine, hydroquinone is used as a topical application in skin whitening to reduce the color of skin. In 2006, the United States Food and Drug Administration revoked its previous approval of hydroquinone and proposed a ban on all over-the-counter preparations. The FDA stated that hydroquinone cannot be ruled out as a potential carcinogen. This conclusion was reached based on the extent of absorption in humans and the incidence of neoplasms in rats in several studies where adult rats were found to have increased rates of tumours, including thyroid follicular cell hyperplasias, anisokaryosis, mononuclear cell leukemia, hepatocellular adenomas and renal tubule cell adenomas. Numerous studies have revealed that hydroquinone can cause exogenous ochronosis, a disfiguring disease in which blue-black pigments are deposited onto the skin, if taken orally; however, skin preparations containing the ingredient are administered topically. The FDA has classified hydroquinone currently as a safe product, as currently used. (Wikipedia)

Contaminant Sources

Clean Air Act Chemicals
Cosmetic Chemicals
FooDB Chemicals
HMDB Contaminants - Urine
HPV EPA Chemicals
IARC Carcinogens Group 3
OECD HPV Chemicals
STOFF IDENT Compounds
T3DB toxins
Tobacco Smoke Compounds
ToxCast & Tox21 Chemicals

Contaminant Type

Cigarette Toxin
Food Toxin
Household Toxin
Human Neurotoxin
Metabolite
Organic Compound
PFAS
Phytotoxin
Pollutant
Synthetic Compound

Chemical Structure

MOL SDF 3D-SDF PDB SMILES InChI View 3D Structure

Synonyms

Value	Source
1,4-Benzenediol	ChEBI
1,4-Dihydroxybenzene	ChEBI
4-Hydroxyphenol	ChEBI
Benzene-1,4-diol	ChEBI
Eldoquin	ChEBI
p-Benzenediol	ChEBI
p-Hydroquinone	ChEBI
p-Hydroxyphenol	ChEBI
Quinol	ChEBI
Artra	MeSH
Eldopaque	MeSH
Esoterica	MeSH
Hidroquilaude	MeSH
Hidroquin	MeSH
Hidroquinona isdin	MeSH
Licostrata	MeSH
Lustra	MeSH
Melanasa	MeSH
Melanex	MeSH
Melpaque	MeSH
Melquin	MeSH
Neostrata HQ	MeSH
Phiaquin	MeSH
Solaquin	MeSH
Ultraquin	MeSH
beta-Quinol	MeSH
Hydroquinone, copper (1+) salt	MeSH
Hydroquinone, lead (2+) salt (2:1)	MeSH
Hydroquinone, monocopper (2+) salt	MeSH
1,4-Dihydroxy-benzeen	HMDB
1,4-Dihydroxy-benzol	HMDB
1,4-Dihydroxybenzen	HMDB
1,4-Diidrobenzene	HMDB
a-Hydroquinone	HMDB
alpha-Hydroquinone	HMDB
b-Quinol	HMDB
Benzohydroquinone	HMDB
Benzoquinol	HMDB
Dihydroquinone	HMDB
Dihydroxybenzene	HMDB
Hydrochinon	HMDB
Hydrochinone	HMDB
Hydroquinol	HMDB
Hydroquinole	HMDB
Hydroquinone for synthesis	HMDB
Hydroquinone GR	HMDB
Hydroquinoue	HMDB
Idrochinone	HMDB
p-Dihydroxybenzene	HMDB
P-Dioxobenzene	HMDB
p-Dioxybenzene	HMDB
P-Hydroxybenzene	HMDB
Solaquin forte	HMDB
Eldoquin forte	MeSH, HMDB
Stratus brand 1 OF hydroquinone	MeSH, HMDB
ICN brand 1 OF hydroquinone	MeSH, HMDB
Plough brand 2 OF hydroquinone	MeSH, HMDB
Eldopaque forte	MeSH, HMDB
ICN brand 4 OF hydroquinone	MeSH, HMDB
Black and white	MeSH, HMDB
ICN brand 2 OF hydroquinone	MeSH, HMDB
ICN brand 3 OF hydroquinone	MeSH, HMDB
Plough brand 1 OF hydroquinone	MeSH, HMDB
Stratus brand 2 OF hydroquinone	MeSH, HMDB
1,4-Benzoquinol	PhytoBank
1,4-Phenylenediol	PhytoBank
1,4-p-Benzenediol	PhytoBank
p-Dihydroquinone	PhytoBank
p-Phenylenediol	PhytoBank
p-Quinol	PhytoBank

Chemical Formula

C₆H₆O₂

Average Molecular Mass

110.111 g/mol

Monoisotopic Mass

110.037 g/mol

CAS Registry Number

123-31-9

IUPAC Name

benzene-1,4-diol

Traditional Name

α-hydroquinone

SMILES

OC1=CC=C(O)C=C1

InChI Identifier

InChI=1S/C6H6O2/c7-5-1-2-6(8)4-3-5/h1-4,7-8H

InChI Key

QIGBRXMKCJKVMJ-UHFFFAOYSA-N

Chemical Taxonomy

Description

belongs to the class of organic compounds known as hydroquinones. Hydroquinones are compounds containing a hydroquinone moiety, which consists of a benzene ring with a hydroxyl groups at positions 1 and 4.

Kingdom

Super Class

Class

Sub Class

Direct Parent

Alternative Parents

Substituents

Hydroquinone
1-hydroxy-2-unsubstituted benzenoid
Monocyclic benzene moiety
Organic oxygen compound
Hydrocarbon derivative
Organooxygen compound
Aromatic homomonocyclic compound

Molecular Framework

Aromatic homomonocyclic compounds

External Descriptors

hydroquinones (CHEBI:17594 )
benzenediol (CHEBI:17594 )
an electron-transfer-related quinol (HYDROQUINONE )
a benzenediol (HYDROQUINONE )

Biological Properties

Status

Detected and Not Quantified

Origin

Exogenous

Cellular Locations

Cytoplasm
Extracellular

Biofluid Locations

Not Available

Tissue Locations

Bone Marrow
Fibroblasts
Kidney
Liver
Skin
Stratum Corneum

Pathways

Not Available

Applications

Not Available

Biological Roles

Chemical Roles

Not Available

Physical Properties

State

Solid

Appearance

Hydroquinone is a white granular solid at room temperature and pressure.

Experimental Properties

Property	Value
Melting Point	172.3 °C
Boiling Point	286°C (546.8°F)
Solubility	72.0 mg/mL at 25 °C

Predicted Properties

Property	Value	Source
Water Solubility	95.5 g/L	ALOGPS
logP	0.71	ALOGPS
logP	1.37	ChemAxon
logS	-0.06	ALOGPS
pKa (Strongest Acidic)	9.68	ChemAxon
pKa (Strongest Basic)	-5.9	ChemAxon
Physiological Charge	0	ChemAxon
Hydrogen Acceptor Count	2	ChemAxon
Hydrogen Donor Count	2	ChemAxon
Polar Surface Area	40.46 Å²	ChemAxon
Rotatable Bond Count	0	ChemAxon
Refractivity	30.02 m³·mol⁻¹	ChemAxon
Polarizability	10.75 Å³	ChemAxon
Number of Rings	1	ChemAxon
Bioavailability	1	ChemAxon
Rule of Five	Yes	ChemAxon
Ghose Filter	No	ChemAxon
Veber's Rule	No	ChemAxon
MDDR-like Rule	No	ChemAxon

Spectra

Spectrum Type	Description	Splash Key	View
GC-MS	GC-MS Spectrum - GC-MS (2 TMS)	splash10-0f79-2490000000-6b4fec222a3499d93790	Spectrum
GC-MS	GC-MS Spectrum - EI-B (Non-derivatized)	splash10-03di-9800000000-c90fd4986fea9691ecbf	Spectrum
GC-MS	GC-MS Spectrum - EI-B (Non-derivatized)	splash10-03e9-9300000000-f8b11742557329691e8a	Spectrum
GC-MS	GC-MS Spectrum - GC-MS (Non-derivatized)	splash10-0f79-2490000000-6b4fec222a3499d93790	Spectrum
GC-MS	GC-MS Spectrum - GC-EI-TOF (Non-derivatized)	splash10-0f79-2690000000-7306adcc7121a11d67cc	Spectrum
Predicted GC-MS	Predicted GC-MS Spectrum - GC-MS (Non-derivatized) - 70eV, Positive	splash10-03di-5900000000-954dc96d8e3eb85b8324	Spectrum
Predicted GC-MS	Predicted GC-MS Spectrum - GC-MS (2 TMS) - 70eV, Positive	splash10-00e9-8950000000-512c0cf5ddc0b120ec8e	Spectrum
Predicted GC-MS	Predicted GC-MS Spectrum - GC-MS (Non-derivatized) - 70eV, Positive	Not Available	Spectrum
Predicted GC-MS	Predicted GC-MS Spectrum - GC-MS (Non-derivatized) - 70eV, Positive	Not Available	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - Quattro_QQQ 10V, Positive (Annotated)	splash10-03di-9600000000-e670ba090cb27367db12	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - Quattro_QQQ 25V, Positive (Annotated)	splash10-01p6-9000000000-5fc32c7688c1612df1e7	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - Quattro_QQQ 40V, Positive (Annotated)	splash10-000i-9000000000-c5853ce8ef225ea5c353	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - EI-B (Unknown) , Positive	splash10-03di-9800000000-c90fd4986fea9691ecbf	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - , negative	splash10-0a4i-0900000000-5635f0157cd37deb1121	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - , positive	splash10-03di-2900000000-05be113033a709130eed	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - 20V, Negative	splash10-0a4i-9600000000-e0d15b2e4ea35a7a76be	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - 20V, Positive	splash10-01r6-9000000000-946504408977df40269a	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - 10V, Negative	splash10-0a4i-0900000000-c16180dd26c127563155	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - 40V, Positive	splash10-03dl-9000000000-cea1cb486f12ea31e3a1	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - 10V, Positive	splash10-01ox-9000000000-3a9d5710c88793e698f1	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - 40V, Negative	splash10-0006-9000000000-60eeaa79bff371773b2e	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - 20V, Negative	splash10-0a4i-0900000000-3a9e293da186985db7fa	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - 40V, Negative	splash10-0pb9-9000000000-84bb0a9b4c3cd16da2a7	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - 10V, Negative	splash10-0a4i-7900000000-2256214c81a3e04e01b7	Spectrum
Predicted LC-MS/MS	Predicted LC-MS/MS Spectrum - 10V, Positive	splash10-03di-0900000000-8d8328e4f7cd2ebaa27d	Spectrum
Predicted LC-MS/MS	Predicted LC-MS/MS Spectrum - 20V, Positive	splash10-03di-1900000000-9290fcb93f170fc3143f	Spectrum
Predicted LC-MS/MS	Predicted LC-MS/MS Spectrum - 40V, Positive	splash10-01si-9200000000-9f707b9d0c4ad0b73b30	Spectrum
Predicted LC-MS/MS	Predicted LC-MS/MS Spectrum - 10V, Negative	splash10-0a4i-0900000000-d3aae38632ac4c40fd4f	Spectrum
Predicted LC-MS/MS	Predicted LC-MS/MS Spectrum - 20V, Negative	splash10-0a4i-0900000000-74f15490ba4f49cf8c18	Spectrum
Predicted LC-MS/MS	Predicted LC-MS/MS Spectrum - 40V, Negative	splash10-0a4i-9800000000-1cb01248e88fce387578	Spectrum
Predicted LC-MS/MS	Predicted LC-MS/MS Spectrum - 10V, Negative	splash10-0a4i-0900000000-9f2c82efe2cba7470e17	Spectrum
Predicted LC-MS/MS	Predicted LC-MS/MS Spectrum - 20V, Negative	splash10-0a4i-0900000000-9f2c82efe2cba7470e17	Spectrum
Predicted LC-MS/MS	Predicted LC-MS/MS Spectrum - 40V, Negative	splash10-0f6x-9000000000-8213c13cc381b346f976	Spectrum
Predicted LC-MS/MS	Predicted LC-MS/MS Spectrum - 10V, Positive	splash10-03di-0900000000-fd10fd64675560620b8d	Spectrum
MS	Mass Spectrum (Electron Ionization)	splash10-03di-9500000000-1fa8477944a662535e76	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
2D NMR	[1H,13C] 2D NMR Spectrum	Not Available	Spectrum

Toxicity Profile

Route of Exposure

Not Available

Mechanism of Toxicity

Not Available

Metabolism

Not Available

Toxicity Values

Not Available

Lethal Dose

Not Available

Carcinogenicity (IARC Classification)

3, not classifiable as to its carcinogenicity to humans. (15)

Uses/Sources

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.

Minimum Risk Level

Not Available

Health Effects

Not Available

Symptoms

Not Available

Treatment

Not Available

Concentrations

Not Available

External Links

DrugBank ID