1,4-Benzoquinone, commonly known as para-quinone, is a chemical compound with the formula C6H4O2. In a pure state, it forms bright-yellow crystals with a characteristic irritating odour, resembling that of chlorine, bleach, and hot plastic. This six-membered ring compound is the oxidised derivative of 1,4-hydroquinone. The molecule is multifunctional: it exhibits properties of a ketone, forming an oxime; an oxidant, forming the dihydroxy derivative; and an alkene, undergoing addition reactions, especially those typical for α,β-unsaturated ketones. 1,4-Benzoquinone is sensitive toward both strong mineral acids and alkali, which cause condensation and decomposition of the compound. 
1,4-Benzoquinone is used:
- In the manufacture of unsaturated polyesters as a polymerisation inhibitor;
- A raw material for production of hydroquinone;
- In a reaction with trialkylboranes to produce alkyl substituted hydroquinones;
- In the manufacture of fungicides;
- As an analytical reagent and an oxidizing agent in photography;
- In adhesive mixtures;
- In coal analysis (dehydrogenation of coal)
- In the pharmaceutical industry for production of cortisone & as an addition compound with barbiturates;
- In the polymer & resins industry;
- As a tanning agent for leather industry;
- In the manufacture of quinhydrone electrodes for use for pH determinations.
Sources and Routes of Exposure
Sources of Exposure 
Occupational exposure to 1,4-Benzoquinone may occur in the dye, textile, chemical, tanning, and cosmetic industries.
Inhalation exposure to 1,4-Benzoquinone may occur from tobacco smoke.
Routes of Exposure 
1,4-Benzoquinone can be absorbed into the body by inhalation and by ingestion.
Health Effects 
Acute exposure to high levels of 1,4-Benzoquinone, via inhalation in humans, is highly irritating to the eyes, resulting in discoloration of the conjunctiva and cornea, while dermal exposure causes dermatitis with skin discoloration and erythema.
Animal studies have reported effects on the kidneys from exposure to 1,4-Benzoquinone.
Tests involving acute exposure of rats have shown 1,4-Benzoquinone to have high acute toxicity from oral exposure.
Chronic dermal contact to 1,4-Benzoquinone in humans may result in skin ulceration, while chronic inhalation exposure may result in visual disturbances.
EPA has not established a Reference Concentration (RfC) or Reference Dose (RfD) for 1,4-Benzoquinone.
No information is available on the reproductive or developmental effects of 1,4-Benzoquinone in humans or animals.
No information is available on the carcinogenic effects of 1,4-Benzoquinone in humans.
1,4-Benzoquinone has been tested (in older animal studies) by dermal application, inhalation, and subcutaneous injection. However, the results are insufficient to evaluate the carcinogenicity of the compound.
EPA has not classified 1,4-Benzoquinone for carcinogenicity.
IARC has classified 1,4-Benzoquinone as a Group 3, not classifiable as to the carcinogenicity to humans.
First Aid Measures
Eye Contact: Check for and remove any contact lenses. In case of contact, immediately flush eyes with plenty of water for at least 15 minutes. Cold water may be used. Get medical attention immediately.
Skin Contact: In case of contact, immediately flush skin with plenty of water for at least 15 minutes while removing contaminated clothing and shoes. Cover the irritated skin with an emollient. Cold water may be used. Wash clothing before reuse. Thoroughly clean shoes before reuse. Get medical attention immediately.
Serious Skin Contact: Wash with a disinfectant soap and cover the contaminated skin with an anti-bacterial cream. Seek immediate medical attention.
Inhalation: If inhaled, remove to fresh air. If not breathing, give artificial respiration. If breathing is difficult, give oxygen. Get medical attention immediately.
Serious Inhalation: Evacuate the victim to a safe area as soon as possible. Loosen tight clothing such as a collar, tie, belt or waistband. If breathing is difficult, administer oxygen. If the victim is not breathing, perform mouth-to-mouth resuscitation.
WARNING: It may be hazardous to the person providing aid to give mouth-to-mouth resuscitation when the inhaled material is toxic, infectious or corrosive. Seek immediate medical attention.
Ingestion: If swallowed, do not induce vomiting unless directed to do so by medical personnel. Never give anything by mouth to an unconscious person. Loosen tight clothing such as a collar, tie, belt or waistband. Get medical attention immediately.
Fire and Explosion Information
- 1,4-Benzoquinone may be combustible at high temperature.
- Auto-ignition temperature is 560°C (1040°F)
- Dry chemical powder should be used to fight small fires
- For large fires, water spray, fog or foam should be used.
- 1,4-Benzoquinone in powder form, capable of creating a dust explosion.
Exposure Controls & Personal Protection
Use process enclosures, local exhaust ventilation, or other engineering controls to keep airborne levels below recommended exposure limits.
If user operations generate dust, fume or mist, use ventilation to keep exposure to airborne contaminants below the exposure limit.
Personal Protective Equipment
The following personal protective equipment is recommended when handling 1,4-Benzoquinone:
- Splash goggles;
- Synthetic apron;
- Vapour and dust respirator (be sure to use an approved/certified respirator or equivalent);
Personal protective equipment in case of a large spill:
- Splash goggles;
- Full suit;
- Vapour and dust respirator;
- A self-contained breathing apparatus should be used to avoid inhalation of the product. Suggested protective clothing might not be sufficient; consult a specialist BEFORE handling this product.
United States 
OSHA: The United States Occupational Safety & Health Administration has set the following Permissible Exposure Limit (PEL) for 1,4-Benzoquinone:
- General Industry: 0.1 ppm, 0.4 mg/m3
- Construction Industry: 0.1 ppm, 0.4 mg/m3 TWA
ACGIH: The American Conference of Governmental Industrial Hygienists has set a Threshold Limit Value (TLV)for 1,4-Benzoquinone of 0.1 ppm, 0.44 mg/m3 TWA
NIOSH: The National Institute for Occupational Safety and Health has set a Recommended Exposure Limit (REL)for 1,4-Benzoquinone of 0.1 ppm TWA
Safe Work Australia: Safe Work Australia has set a time weighted average concentration (TWA) for 1,4-Benzoquinone of 0.1 ppm, 0.44 mg/m3 for a 40-hour workweek.