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Skin conditioning agents and actives

Hydroquinone

Also known as Benzene-1,4-diol, 1,4-benzenediol, 1,4-Dihydroxybenzene

CAS 123-31-9Formula C6H6O2Molar mass 110.11 g/molEC 204-617-8
GHS signal word: Danger. Pictograms: Corrosive, Harmful or irritant, Serious health hazard, Hazardous to the environment 265 suppliers listed Drug substance
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Hydroquinone chemical structure, C6H6O2, CAS 123-31-9
2D chemical structure

Key facts

What buyers check first

All properties
Appearance
White crystals
Melting point
170 to 171
Boiling point
285 to 287
Density
1.330 g/cm³ at 20 °C
Flash point
165 °C
HS code
290722
Category
Skin conditioning agents and actives
UN number
UN 2662
Illustrative photo, colourless crystals in small glass vials on a laboratory bench
Typical packagingIllustrative packaging image, not the actual product

What is Hydroquinone?

Plain description, key identifiers and synonyms

Hydroquinone is a benzenediol comprising benzene core carrying two hydroxy substituents para to each other. It has a role as an antioxidant, a cofactor, a carcinogenic agent, a mouse metabolite, a human xenobiotic metabolite, an Escherichia coli metabolite and a skin lightening agent. It is a benzenediol and a member of hydroquinones.

Identifiers

Registry numbers, names and line notations, tap to copy

IUPAC name
benzene-1,4-diol
CAS number
123-31-9 CAS number cross-checked
EC number
204-617-8
Molecular formula
C6H6O2
UNII
XV74C1N1AE
MDL number
MFCD00002339
INCI name
HYDROQUINONE
InChIKey
QIGBRXMKCJKVMJ-UHFFFAOYSA-N
InChI
InChI=1S/C6H6O2/c7-5-1-2-6(8)4-3-5/h1-4,7-8H
SMILES (canonical and isomeric)
C1=CC(=CC=C1O)O

Synonyms

  • Benzene-1,4-diol
  • 1,4-benzenediol
  • 1,4-Dihydroxybenzene
  • Quinol
  • p-Hydroquinone
  • p-Hydroxyphenol
  • p-Benzenediol
  • p-Dihydroxybenzene
  • 4-Hydroxyphenol
  • hydroquinol
  • Benzoquinol
  • Eldopaque
  • Eldoquin
  • Hydroquinole
  • Phiaquin
  • Tecquinol
  • p-Dioxybenzene
  • Solaquin forte
  • Idrochinone
  • Benzohydroquinone
  • Hidroquinone
  • Arctuvin
  • Tequinol
  • Dihydroxybenzene
  • Tenox HQ
Show all 39 synonyms
  • Eldopaque Forte
  • Eldoquin Forte
  • Hydrochinon
  • Usaf ek-356
  • Diak 5
  • Benzene, p-dihydroxy-
  • 1,4-Dihydroxy-benzol
  • 1,4-Diidrobenzene
  • p-Dioxobenzene
  • 1,4-Dihydroxybenzen
  • para-Dioxybenzene
  • para-Hydroquinone
  • Pyrogentistic acid
  • Black and White Bleaching Cream

Physical and chemical properties

Measured values and descriptors computed from the structure

Physical and chemical properties

Measured values, check the supplier specification for your grade

Appearance
White crystalsexp.
Odour
Odorlessexp.
Taste
A slightly bitter taste in aqueous solutionsexp.
Melting point
170 to 171exp.
Boiling point
285 to 287exp.
Density
1.330 g/cm³ at 20 °Cexp.
Flash point
165 °Cexp.
Autoignition temperature
516 °Cexp.
Solubility
In water, 72,000 mg/L at 25 °Cexp.
Vapour pressure
1.9 × 10⁻⁵ mm Hg at 25 °Cexp.

Values vary by grade. Ask suppliers for the COA or TDS of the batch you buy.

Computed descriptors

Calculated from the structure, useful for screening and formulation

Molecular weight
110.11 g/molcalc.
Exact mass
110.0368 Dacalc.
LogP (octanol/water)
1.1calc.
Topological polar surface area
40.46 Ųcalc.
Hydrogen bond donors
2calc.
Hydrogen bond acceptors
2calc.
Rotatable bonds
0calc.
Heavy atoms
8calc.
Rings
1calc.
Aromatic rings
1calc.
Fraction sp3 carbons
0calc.
Formal charge
0calc.
Stereocentres
0calc.
Lipinski rule of five
Passes (0 violations)calc.

Calculated for screening. Confirm critical figures with the supplier.

Murcko scaffold

The ring system that remains when every side chain is removed

Murcko scaffold of this chemical, c1ccccc1

c1ccccc1

1 ring, 6 atoms, the Benzene ring system.

485,677 other chemicals share this scaffold

Safety and hazards

GHS classification summary, not a safety data sheet

GHS signal word
Danger
GHS05: Corrosive
Corrosive
GHS07: Harmful or irritant
Harmful or irritant
GHS08: Serious health hazard
Serious health hazard
GHS09: Hazardous to the environment
Hazardous to the environment
120NFPA 704 rating

Hazard statements

  • H302Harmful if swallowed.
  • H317May cause an allergic skin reaction.
  • H318Causes serious eye damage.
  • H341Suspected of causing genetic defects.
  • H351Suspected of causing cancer.
  • H400Very toxic to aquatic life.
Precautionary statements (20)
  • P203Obtain, read and follow all safety instructions before use.
  • P261Avoid breathing dust, fume, gas, mist, vapours or spray.
  • P264Wash skin thoroughly after handling.
  • P264 + P265Wash skin thoroughly after handling. Do not touch eyes.
  • P270Do not eat, drink or smoke when using this product.
  • P272Contaminated work clothing should not be allowed out of the workplace.
  • P273Avoid release to the environment.
  • P280Wear protective gloves, protective clothing, eye protection and face protection.
  • P301 + P317If swallowed: Get medical help.
  • P302 + P352If on skin: Wash with plenty of water.
  • P305 + P354 + P338If in eyes: Immediately rinse with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
  • P317Get medical help.
  • P318If exposed or concerned, get medical advice.
  • P321Specific treatment (see supplemental first aid instructions on the label).
  • P330Rinse mouth.
  • P333 + P317If skin irritation or rash occurs: Get medical help.
  • P362 + P364Take off contaminated clothing. And wash it before reuse.
  • P391Collect spillage.
  • P405Store locked up.
  • P501Dispose of contents and container in accordance with local regulations.
UN number
UN 2662
Transport hazard class
6.1
Packing group
III

GHS classification summary, not a safety data sheet (SDS). Classifications can differ by supplier, grade and concentration. Always check the supplier's SDS.

Full safety data and first aid

Hydroquinone suppliers

Sponsored listings first, then the documented ranking: membership, verification, replies, completeness, freshness and ratings

All 265 suppliers
30 of 30 offers

Suppliers marked Unclaimed profile have not claimed their profile yet. They are not verified by CompoundList, their offers are price on request and details may have changed, so please confirm them with the supplier. Company representatives can claim a profile with a business email on the company's own website domain. Our team verifies each claim and sends the result by email.

Where suppliers are based

265 suppliers in 34 countries

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Hydroquinone price

Indicative price range per kg from live supplier offers

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Uses and applications

What the substance is used for, by industry and function

The largest demand for hydroquinone is as a photographic developer, principally for black-and-white film, lithography, photochemical machining, microfilm, and X-ray film. ... The second largest consumer of hydroquinone is the rubber industry, which requires hydroquinone for the production of antioxidants and antiozonants.

Used extensively in the vinyl monomer industry to inhibit free-radical polymerization during both processing and storage ... Used as stabilizers for unsaturated polyester resins.

Hydroquinone is an aromatic compound that functions in cosmetics as an antioxidant, fragrance, reducing agent, or polymerization inhibitor...

Hydroquinone (U.S.P. grade) ... (is) used in topical formulations as (a) skin bleaching and depigmenting agent.

Hydroquinone is used as a developing agent in black-and-white photography, lithography, and x-ray films.

Read more

It is also used as an intermediate to produce antioxidants for rubber and food. It is added to a number of industrial monomers to inhibit polymerization during shipping, storage, and processing.

Industrial uses: Polymerization promoter, Solvent, Antioxidant, Corrosion inhibitor, Intermediate, Photosensitive agent.

Consumer uses: Photosensitive agent.

Use classes: Pesticide transformation products, Cosmetics.

Cosmetic ingredient, INCI name HYDROQUINONE(antioxidant, bleaching, hair dyeing, fragrance)

Pharmacological actions

  • Antioxidants
  • Mutagens
  • Radiation-Protective Agents

Roles

  • Escherichia coli metabolite
  • aetiopathogenetic role
  • animal metabolite
  • antioxidant
  • bacterial metabolite
  • carcinogenic agent
  • cofactor
  • cosmetic
  • eukaryotic metabolite
  • human metabolite
  • human xenobiotic metabolite
  • mammalian metabolite
  • metabolite
  • mouse metabolite
  • prokaryotic metabolite
  • skin lightening agent
  • xenobiotic metabolite

Functional uses

  • Antioxidant
  • Bleaching agent
  • Dye
  • Flavouring and nutrient
  • Fragrance
  • Monomers
  • Reducing agent
  • Stabilizing agent

Cosmetic functions

  • Antioxidant
  • Bleaching
  • Fragrance
  • Hair dyeing
  • Reducing

Pharmacology

Hydroquinone is a Melanin Synthesis Inhibitor. The mechanism of action of hydroquinone is as a Melanin Synthesis Inhibitor. The physiologic effect of hydroquinone is by means of Depigmenting Activity.

How it is made

P-Diisopropylbenzene (p-DIPB) is produced by Friedel-Crafts alkylation of benzene with propene. Purified p-DIPB is subsequently converted to the dihydroperoxide (DHP) by air oxidation under slightly alkaline conditions at 80 - 90 °C. The DHP is separated from the reaction mixture either by extraction or by crystallization, and is then cleaved to hydroquinone and acetone by an acid-catalyzed Hock rearrangement, the DHP solution is treated with sulfuric acid catalyst (0.2 - 1.0%) at 60 - 80 °C. The hydroquinone is crystallized and isolated.

Read more

The overall yield of hydroquinone (based on p-DIPB) is ca. 80%.

The catalyzed hydroxylation of phenol at ca. 80 °C with 70% aqueous hydrogen peroxide produces a mixture of hydroquinone and catechol. The catalyst may be a strong mineral acid, iron(II), or a cobalt(II) salt. Depending on catalyst selection, the ratio of catechol to hydroquinone can be varied from 3:1 to 0.1:1, in practice, the ratio is typically 1.5:1, i.e., catechol is the major product. The reaction proceeds by an ionic mechanism in which hydrogen peroxide is polarized by the strong acid catalyst and phenol is subsequently hydroxylated the resulting isomers are separated by a series of extractions and solvent-stripping operations. The ratio of the products hydroquinone and catechol may be influenced by the presence of superacids or shape-selective zeolites.

Regulatory status

Inventories, regulations and trade controls that list this substance

Europe

  • EU harmonised classification (CLP Annex VI)
    Index no: 604-005-00-4

Health and food

  • EU cosmetic ingredient inventory
  • EU Cosmetics Regulation Annex II, prohibited in cosmetics
    Name: 1,4-Dihydroxybenzene (Hydroquinone), with the exception of entry 14 in Annex III, Ref no: 1339, Annex ref: II/1339
  • EU Cosmetics Regulation Annex III, restricted in cosmetics
    Name: HYDROQUINONE, Ref no: 14, Annex ref: III/14
  • Active ingredient in FDA approved drug labels

United States

  • TSCA inventory (USA)
    Status: Active in US commerce

HS code and trade data

Customs classification and reported world trade statistics

Global trade

World import and export statistics for the HS code Hydroquinone is traded under.

HS 2907.22Exact HS code

Hydroquinone (quinol) and its salts

World exports in 2024
$155M
−4.9% vs 2023, imports $162M
2019 to 2024
Top exporters
  1. United States33.1%
  2. Japan18.2%
  3. China17.8%
Top importers
  1. China21.2%
  2. India * partner reported16.1%
  3. South Korea7.5%

* Partner reported figures, a lower bound.

Reported customs values in USD, not prices.Full trade data

The HS code shown for Hydroquinone is indicative (it was matched by name in the HS nomenclature). Confirm the classification with your customs broker before shipping.

Frequently asked questions

Quick answers about Hydroquinone, based on the data on this page

What is Hydroquinone?

Hydroquinone is a benzenediol comprising benzene core carrying two hydroxy substituents para to each other. It has a role as an antioxidant, a cofactor, a carcinogenic agent, a mouse metabolite, a human xenobiotic metabolite, an Escherichia coli metabolite and a skin lightening agent.

What is the CAS number of Hydroquinone?

The CAS registry number of Hydroquinone is 123-31-9.

What is the molecular formula and weight of Hydroquinone?

The molecular formula of Hydroquinone is C6H6O2 and its molar mass is 110.11 g/mol.

What is Hydroquinone used for?

The largest demand for hydroquinone is as a photographic developer, principally for black-and-white film, lithography, photochemical machining, microfilm, and X-ray film. ...

Is Hydroquinone hazardous?

Hydroquinone carries the GHS signal word "Danger". Main hazards: harmful if swallowed, may cause an allergic skin reaction, causes serious eye damage. This summary is not an SDS, always read the supplier safety data sheet.

What is the HS code of Hydroquinone?

Hydroquinone is usually classified under HS code 290722 (Hydroquinone (quinol) and its salts). This is indicative, confirm it with your customs broker before shipping.

Where can I buy Hydroquinone?

CompoundList lists 265 suppliers of Hydroquinone in China, United States, India, Canada and 30 more. Send one free request to get and compare quotes. Your contact details stay private until you accept a quote.

Where can I buy Hydroquinone in India?

56 suppliers in India list Hydroquinone on CompoundList. Filter the suppliers list by country and send a request to compare prices, grades and delivery times.

What is the price of Hydroquinone?

Suppliers quote Hydroquinone on request because prices depend on grade, purity, quantity and destination. A free request on CompoundList gets you several quotes to compare.

Guides for buyers

Practical guides that help when you source, ship or handle Hydroquinone

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Data last updated 7 Oct 2026. Details may have changed, please confirm them with the supplier. Report an error on this page
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