Hydroxyquinone

Hydroxyquinone - Names and Identifiers

Name	Hydroquinone
Synonyms	Quinol Melanex Idrochinone HYDROQUINONE HYDROCHINONE Hydroquinone HYDROXYQUINOL Hydroxyquinone 1,4-Benzenediol benzene-1,4-diol AKOS BBS-00004220 1,4-Dihydroxybenzene 1,4-Dihydroxy benzene hydroquinone--1,4-benzenediol 6,7-dihydroxy-2H-chromen-2-one
CAS	123-31-9
EINECS	204-617-8
InChI	InChI=1/C9H6O4/c10-6-3-5-1-2-9(12)13-8(5)4-7(6)11/h1-4,10-11H
InChIKey	QIGBRXMKCJKVMJ-UHFFFAOYSA-N

Hydroxyquinone - Physico-chemical Properties

Molecular Formula	C6H6O2
Molar Mass	110.11
Density	1.32
Melting Point	172-175°C(lit.)
Boling Point	285°C(lit.)
Flash Point	165 °C
Water Solubility	70 g/L (20 ºC)
Solubility	H2O: 50mg/mL, clear
Vapor Presure	1 mm Hg ( 132 °C)
Vapor Density	3.81 (vs air)
Appearance	Needle-Like Crystals or Crystalline Powder
Color	White to off-white
Exposure Limit	NIOSH REL: 15-min ceiling 2, IDLH 50; OSHA PEL: TWA 2;ACGIH TLV: TWA 2 (adopted).
Merck	14,4808
BRN	605970
pKa	10.35(at 20℃)
Storage Condition	Store below +30°C.
Stability	Stable. Combustible. Incompatible with strong oxidizing agents, strong bases, oxygen, ferric salts. Light and air-sensitive. Discolours in air.
Sensitive	Air & Light Sensitive
Refractive Index	1.6320
Physical and Chemical Properties	Character: White needle crystal. melting point 172~175 ℃ boiling point 285~287 ℃ relative density 1.328g/cm3 flash point 165 ℃ solubility, ethanol and ether, benzene-soluble.
Use	Used as imaging agent and dye, drug raw material

Hydroxyquinone - Risk and Safety

Risk Codes	R22 - Harmful if swallowed R40 - Limited evidence of a carcinogenic effect R41 - Risk of serious damage to eyes R43 - May cause sensitization by skin contact R50 - Very Toxic to aquatic organisms R68 - Possible risk of irreversible effects
Safety Description	S26 - In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. S36/37/39 - Wear suitable protective clothing, gloves and eye/face protection. S61 - Avoid release to the environment. Refer to special instructions / safety data sheets.
UN IDs	2662
WGK Germany	3
RTECS	MX3500000
TSCA	Yes
HS Code	29072210
Hazard Class	9
Packing Group	III
Toxicity	LD50 orally in rats: 320 mg/kg (Woodard)

Hydroxyquinone - Upstream Downstream Industry

Raw Materials	DV Methyl chrysanthemate Aniline Oxalic acid Charcoal Sodium metabisulfite Sulfuric acid Manganese Iron Zinc
Downstream Products	Sodium carbonate Hydroquinone Dimethyl Ammonia Ammonium chloride Ammonium Bicarbonate 4-Methoxyphenol

Hydroxyquinone - Nature

Open Data Verified Data

White needle-like crystals. Soluble in alcohol and ether, soluble in water, slightly soluble in benzene. Visible light in the air easily turned to light red. The aqueous solution can be oxidized to Brown in air. Flammable in case of open flame and high heat. Reactions with strong oxidants may occur. By high heat decomposition of toxic gases. Hydroquinone is a weak acid. It reacts with most of the oxidizing agents and is converted to O-and p-benzoquinones. Hydroquinone has a, beta and gamma; Three crystal forms. Type A is a triangular needle-like or diamond-like crystal, crystallized from water and stable. Lu is a triangular crystal, crystallized from methanol, unstable. The & gamma; Type is monoclinic crystal, which is obtained by sublimation method and is unstable. All three crystals can be rubbed to emit fluorescence. Hydroquinone is flammable, but the flash point is high, the vapor pressure is low, if there is no fire, the risk is not big.

Last Update：2025-06-10 22:55:16

Hydroxyquinone - Preparation Method

Open Data Verified Data

aniline is oxidized to p-benzoquinone with manganese dioxide in sulfuric acid medium and then reduced to hydroquinone with iron powder.

Last Update：2022-01-01 09:30:33

Hydroxyquinone - Application

Open Data Verified Data

In the field of water treatment, hydroquinone is added to the hot water and cooling water of the closed-circuit heating and cooling system, and the corrosion inhibition of the water side Metal energy is carried out. Hydroquinone is used as an oxygen scavenger for boiler water, and hydroquinone is added thereto to remove residual dissolved oxygen when the boiler water is preheated for oxygen removal.

Last Update：2025-08-19 16:24:40

Hydroxyquinone - Safety

Open Data Verified Data

rat oral LD50:320mg/kg. Hydroquinone is toxic and flammable. The reduction of hydroquinone is very strong, and it is easy to be oxidized to p-benzoquinone. Hydroquinone is toxic and can cause poisoning through the skin. The oral lethal dose was 0.08-0. 2g/kg. If the oral administration of more than 1g will appear symptoms of acute poisoning, taking 59g can be fatal. In Japan, the maximum allowable concentration of hydroquinone in the air of the production workshop is 2mg/ma. When hydroquinone contact the skin, eyes, immediately with water or saline rinse. According to the relevant information, hydroquinone has a potential carcinogenic effect. Store in a cool, ventilated warehouse. Keep away from fire and heat source. Protection from direct sunlight. Keep the container sealed. Protected from light. It should be stored separately from oxidant, acids and edible chemical raw materials.

Last Update：2022-01-01 09:30:34

Hydroxyquinone - Reference Information

Henry's Law Constant	(x 10-9 atm?m3/mol):
LogP	0.59 at 20℃
NIST chemical information	Information provided by: webbook.nist.gov (external link)
(IARC) carcinogen classification	3 (Vol. 15, Sup 7, 71) 1999
EPA chemical information	Information provided by: ofmpub.epa.gov (external link)
overview	1,4-hydroquinone, also known as hydroquinone, is an important chemical raw material. in recent years, the domestic demand for it has shown a growing trend, and the consumption field has expanded year by year. 1, 4-hydroquinone is widely used. It is an important raw material, intermediate and auxiliary agent for medicine, pesticide, dye and rubber. It is mainly used in developer, anthraquinone dye, azo dye, rubber antioxidant and monomer polymerization inhibitor, food stabilizer and coating antioxidant, petroleum anticoagulant, synthetic ammonia catalyst, etc.
application	1,4-hydroquinone is widely used. it is an important raw material, intermediate and auxiliary agent for medicine, pesticide, dye and rubber, and is mainly used in developer, anthraquinone dye, azo dye, rubber antioxidant and monomer inhibitor, food stabilizer and coating antioxidant, petroleum anticoagulant, ammonia catalyst, etc.
preparation method	at present, the application field of 1,4-hydroquinone is gradually expanding. besides its application in traditional fields, it has also made new developments in chemical fertilizer, water treatment, liquid crystal polymer and other fields. In addition, it can be processed into other fine chemicals. Such as 1, 4-diamino crypto, quinine, etc. In recent years, researchers have paid more attention to the research and development and improvement of the production process of 1,4-hydroquinone and catalysts.
Uses	Used as imaging agent, dye, and pharmaceutical raw material Hydroquinone is the herbicide quiratoxaline, pyriflunoproxyl, thiazolaproxyl, oxazaproxyl, flupircloroxyl, and milk fluopyrene intermediates are also pharmaceutical and dye intermediates. Hydroquinone is mainly used as a developer for photography. Hydroquinone and its alkylates are widely used as polymerization inhibitors added during monomer storage and transportation, and the common concentration is about 200ppm. Hydroquinone methyl ether is an intermediate of edible oil antioxidant BHA; hydroquinone dimethyl ether is an intermediate of dyes, organic pigments and fragrances; hydroquinone diethyl ether is an intermediate of photosensitive pigments and dyes. Hydroquinone is also used to produce N,N'-diphenyl p-phenylenediamine, which is an antioxidant and anti-odor agent for rubber and gasoline. Used as an analytical reagent, reducing agent and developer for copper and gold Colorimetric determination of phosphorus, magnesium, niobium, copper, silicon and arsenic. Polarographic and volumetric determination of iridium. Reducing agents of heteropoly acids, reducing agents of copper and gold. Test phosphate, tungstate, nitrate, nitrite, selenium and tellurium. Photometric determination of phosphorus, magnesium, niobium, copper, silicon and arsenic; polarographic and volumetric determination of iridium; reducing agents of heteropoly acids; reducing agents of copper and gold; testing of phosphate, tungstate, Nitrate, nitrite, selenium and tellurium, etc.; developer; antioxidant; desulfurizer for fertilizer industry; urea synergist
production method	hydroquinone has been produced by aniline method before. at present, industrial production has also developed catechol coproduction method, cumene method and bisphenol a method. The aniline method is still used in China. 1. Aniline is oxidized to p-benzoquinone by manganese dioxide in sulfuric acid medium, and then reduced to hydroquinone by iron powder. The finished product is obtained by concentration, decolorization, crystallization and drying. Industrial grade hydroquinone content ≥ 99%, photographic grade ≥ 99.5%. Raw material consumption quota: aniline 1250 kg/t, sulfuric acid (93%)5500 kg/t, soft manganese ore powder (containing manganese dioxide 60-65%)5950 kg/t, iron powder (containing Fe ≥ 90%)540 kg/t. 2. Using nitrobenzene as raw material, it is prepared by hydrogenation and heating. the preparation method has the following two kinds. Using aniline as raw material, aniline reacts with sulfuric acid to generate aniline sulfate, which is oxidized to benzoquinone by the new ecological oxygen released during the interaction of manganese dioxide and sulfuric acid, and then reacts with iron powder to prepare hydroquinone solution. The finished product is obtained by sedimentation separation, decompression concentration, cooking decolorization and crystallization. Catechol and hydroquinone were prepared by hydrogen peroxide oxidation with phenol as raw material and separated to obtain catechol and hydroquinone respectively.
category	toxic substances
toxicity classification	highly toxic
acute toxicity	oral-rat LD50: 320 mg/kg; Oral-mouse LD50: 245 mg/kg
stimulation data	skin-5% severe
flammability hazard characteristics	open flame is combustible, reacts with oxidant and sodium hydroxide; combustion releases stimulating smoke
storage and transportation characteristics	warehouse ventilation and low temperature drying; Store separately from oxidants and food additives
fire extinguishing agent	carbon dioxide, foam, dry powder, sand, mist water.
occupational standard	TWA 2 mg/m3; STEL 4 mg/m3
auto-ignition temperature	930 °F
toxic substance data	information provided by: pubchem.ncbi.nlm.nih.gov (external link)
immediate life-threatening and health concentration	50 mg/m3

Last Update：2024-04-09 02:00:06

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