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Hydroquinone

CAS Number
123-31-9
EC Number
204-617-8
Chemical Formula
C6H6O2
Molecular Weight
110.11 g/mol

Description

Hydroquinone (CAS 123-31-9 ), commonly abbreviated as HQ, is an aromatic diol used industrially as a polymerization inhibitor, antioxidant, and chemical intermediate. It prevents premature crosslinking in reactive monomers and protects unstable materials during storage. In photographic and printing chemistry, HQ functions as a developing agent that reduces silver halide to metallic silver, controlling image density and contrast. Rubber and polymer manufacturers add it to acrylic and vinyl monomers during production. This addition occurs during transport to suppress unwanted polymerization. As a pharmaceutical intermediate, it supports synthesis of active compounds and is used in topical formulations targeting skin hyperpigmentation for various medical applications. Personal care formulators incorporate HQ into depigmentation products where it inhibits melanin synthesis, subject to regional regulatory limits. The compound is essential for maintaining the stability of sensitive chemical formulations. Hydroquinone is supplied as a white crystalline powder in technical and pharmaceutical grades. USP and BP grades are available to meet compendial requirements for pharmaceutical and cosmetic applications globally. Technical grade is standard for polymer stabilization and industrial chemical synthesis, typically packaged in fiber drums or multi-wall bags. This ensures the material remains stable and free from contaminants during long-term storage. Contact us for supply of Hydroquinone Request Quote

Other Names (Synonyms)

1,4-dihydroxybenzen | 1,4-dihydroxy-benzeen | 1,4-benzenediol | quinol | p-hydroxyphenol | p-hydroxybenzene | p-hydroquinone | p-dioxybenzene | HQ

Key Technical Features

  • High Purity Grade standard
  • Consistent Batch Quality
  • Full Regulatory & REACH Support
  • Global Logistics Network enabled

Physical Properties

Melting Point170-171 °C
Boiling Point285-287 °C
Density1.332 g/cm³
Flash Point165 °C
Appearancewhite needle-like crystals or crystalline powder
ColorWhite to off-white
Odorodorless
FormNeedle-Like Crystals or Crystalline Powder
Water Solubility70 g/L (20 ºC)
Vapor Pressure1 mm Hg ( 132 °C)
Refractive Index1.6320
Log P0.59 at 20℃

Safety & Handling

Danger
GHS05· CorrosiveGHS07· IrritantGHS08· Health HazardGHS09· Environment

Hazard Statements

H302Harmful if swallowed
H312Harmful in contact with skin
H315Causes skin irritation
H316Causes mild skin irritation
H317May cause an allergic skin reaction
H318Causes serious eye damage
H319Causes serious eye irritation
H336May cause drowsiness or dizziness
H340May cause genetic defects
H341Suspected of causing genetic defects
H351Suspected of causing cancer
H360May damage fertility or the unborn child
H370Causes damage to organs
H372Causes damage to organs through prolonged or repeated exposure
H373May causes damage to organs through prolonged or repeated exposure
H400Very toxic to aquatic life
H410Very toxic to aquatic life with long lasting effects H302+
H312Harmful if swallowed or in contact with skin

Precautionary Statements

P203Obtain, consult and follow expert instructions for use.
P260Do not breathe dust/fume/gas/mist/vapours/spray.
P261Avoid breathing dust/fume/gas/mist/vapours/spray.
P264Wash … thoroughly after handling.
P270Do not eat, drink or smoke when using this product.
P271Use only outdoors or in a well-ventilated area.
P272Contaminated work clothing should not be allowed out of the workplace.
P273Avoid release to the environment.
P280Wear protective gloves/protective clothing/eye protection/face protection.
P317Get emergency medical help.
P318IF exposed or concerned, get medical advice.
P319Get medical advice/attention if you feel unwell.
P321Specific treatment (see … on this label).
P330Rinse mouth.
P391Collect spillage.
P405Store locked up.
P501Dispose of contents/container in accordance with local regulations.
P265Wash … thoroughly after handling.
P317Get emergency medical help.
P352IF ON SKIN: Wash with plenty of water.
P340IF INHALED: Remove person to fresh air and keep comfortable for breathing.
P316Get emergency medical help immediately.
P317Get emergency medical help.
P317Get emergency medical help.
P317If eye irritation persists: Get medical advice/attention. Get emergency medical help.
P364Take off contaminated clothing and wash it before reuse.
P233Store in a well-ventilated place. Keep container tightly closed.
P338IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
P338IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.

Trade & Regulatory

HS Code29072200
Storage Class11 - Combustible Solids
WGK (Germany)3