Substance profile
p-benzoquinone
p-benzoquinone is yellow monoclinic prisms from water or petroleum ether with a penetrating odor resembling that of chlorine.
01 · Identification
What p-benzoquinone is
p-benzoquinone is yellow monoclinic prisms from water or petroleum ether with a penetrating odor resembling that of chlorine. Its molecular formula is C6H4O2 and its molecular weight is 108.09 g/mol. It boils at 180 °C, melts at 116 °C.
Under the GHS it carries the signal word Danger. It is classed as hazardous Air Pollutants (HAPs).
02 · Identifiers
p-benzoquinone identifiers and molecular data
p-benzoquinone CAS number and EC number
p-benzoquinone molecular formula and molecular weight
Other names for p-benzoquinone
- quinone
03 · GHS classification
p-benzoquinone hazard classification
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
p-benzoquinone pictograms and signal word
p-benzoquinone hazard class and category
| Hazard class | Category | From code | Pictogram |
|---|---|---|---|
| Acute toxicity - oral GHS chapter 3.1 | Category 3 | H301 | GHS06 |
| Acute toxicity - inhalation GHS chapter 3.1 | Category 3 | H331 | GHS06 |
| Skin corrosion/irritation GHS chapter 3.2 | Category 2 | H315 | GHS07 |
| Serious eye damage/eye irritation GHS chapter 3.3 | Category 2A | H319 | GHS07 |
| Specific target organ toxicity - single exposure GHS chapter 3.8 | Category 3 | H335 | GHS07 |
| Hazardous to the aquatic environment - acute GHS chapter 4.1 | Category 1 | H400 | GHS09 |
p-benzoquinone hazard statements (H-codes)
| Code | Hazard statement |
|---|---|
| H331 | Toxic if inhaled. |
| H301 | Toxic if swallowed. |
| H335 | May cause respiratory irritation. |
| H315 | Causes skin irritation. |
| H319 | Causes serious eye irritation. |
| H400 | Very toxic to aquatic life. |
This page lists only the codes assigned to p-benzoquinone. The full reference lives on the hazard statements hub, the precautionary statements hub and the GHS pictograms hub.
Safety Data Sheet
Getting an SDS for p-benzoquinone
A Safety Data Sheet is written for a product, not for a substance: the supplier of the grade you actually buy issues it, so two suppliers of p-benzoquinone issue two different sheets. That is why there is no single authoritative SDS for a substance to download — what there is, is the job of collecting the sheets for the products you hold and keeping them current as suppliers revise them.
04 · Precautionary statements
p-benzoquinone precautionary statements
CLP Annex VI assigns 19 precautionary statements to p-benzoquinone. They are grouped the way a label groups them: what to do before handling, what to do when something has already happened, how to store it and how to dispose of it.
Prevention
What to do before and during handling so the hazard never happens.
Response
What to do once exposure, spillage or fire has already happened.
Disposal
What has to happen to the contents and the empty container.
Reading the notation. … is a blank the supplier fills in — not a truncated sentence.· [square brackets] mark a part printed only when it applies.
05 · Names in the regulation
p-benzoquinone name in 23 EU languages
CLP Annex VI Part 3 is published in every language edition of the regulation, and the identification column is written out in each of them. Nothing below is translated by us: each line is the name as that edition prints it. Under Art. 18(2) the substance name from Annex VI is a lawful product identifier, so this is the wording to put on a label going to that market — and where the cell lists several designations, any one of them qualifies.
| Language | Name in CLP Annex VI Part 3 |
|---|---|
| Bulgarian български | p -бензохинон хинон |
| Spanish español | p -Benzoquinona quinona |
| Czech čeština | p -benzochinon chinon |
| Danish dansk | p -benzoquinon quinon |
| German Deutsch | p -Benzochinon Chinon |
| Estonian eesti | p -bensokinoon kinoon |
| Greek ελληνικά | p -βενζοκινόνη κινόνη |
| English English | p -benzoquinone quinone |
| French français | p -benzoquinone quinone |
| Croatian hrvatski | p -benzokinon kinon |
| Italian italiano | p -benzochinone chinone |
| Latvian latviešu | p -benzohinons hinons |
| Lithuanian lietuvių | p -benzchinonas chinonas |
| Hungarian magyar | p -benzokinon kinon |
| Maltese Malti | p -benżokinon kwinon |
| Dutch Nederlands | p -benzochinon chinon |
| Polish polski | p -benzochinon 1,4-benzochinonchinon |
| Portuguese português | p -benzoquinona quinona |
| Romanian română | p -benzochinonă chinonă |
| Slovak slovenčina | para -benzochinón chinón |
| Slovenian slovenščina | p -benzokinon kinon |
| Finnish suomi | p -bentsokinoni kinoni |
| Swedish svenska | p -bensokinon kinon |
All 23 language editions of Annex VI carry this entry. Irish is the twenty-fourth official EU language and has no line here for a different reason: no consolidated CLP text has ever been published in Irish, so there is no Irish edition of Annex VI to quote a name from. Source: consolidated CLP, CELEX 02008R1272, language editions. © European Union, https://eur-lex.europa.eu — only the electronic Official Journal of the European Union is authentic.
06 · Label elements
p-benzoquinone GHS label elements
Everything CLP Annex VI fixes for p-benzoquinone, laid out the way it appears on a label. The greyed lines are the parts only the supplier can fill in.
Danger
p-benzoquinone
- Toxic if inhaled.
- Toxic if swallowed.
- May cause respiratory irritation.
- Causes skin irritation.
- Causes serious eye irritation.
- Very toxic to aquatic life.
- Do not breathe dust/fume/gas/mist/vapours/spray.
- Wash … thoroughly after handling.
- Do not eat, drink or smoke when using this product.
- Use only outdoors or in a well-ventilated area.
- Avoid release to the environment.
- Wear protective gloves/protective clothing/eye protection/face protection/hearing protection/…
- IF SWALLOWED:
- IF ON SKIN:
- IF INHALED:
- IF IN EYES:
- Immediately call a POISON CENTER/doctor/…
- Get medical advice/attention.
- Rinse mouth.
- If skin irritation occurs:
- If eye irritation persists:
- Remove contact lenses, if present and easy to do. Continue rinsing.
- Wash with plenty of water/…
- Collect spillage.
- Dispose of contents/container to …
Supplier name, address and telephone number· Product identifier·Nominal quantity
Need this as an actual label? Open p-benzoquinone in the GHS label constructor →
07 · Health hazards
p-benzoquinone health hazards and exposure limits
p-benzoquinone hazard summary
Occupational exposure to quinone may occur in the dye, textile, chemical, tanning, and cosmetic industries. Acute (short-term) exposure to high levels of quinone, via inhalation in humans, results in irritation of the eyes, consisting of discoloration of the conjunctiva and cornea, and causes dermatitis from dermal exposure. Chronic (long-term) inhalation exposure to quinone in humans may result in visual disturbances, and chronic dermal contact causes skin ulceration. No information is available on the reproductive, developmental, or carcinogenic effects of quinone in humans. The results of available animal studies are insufficient to evaluate the carcinogenicity of quinone. EPA has not evaluated quinone for carcinogenicity.
Source: EPA Hazardous Air Pollutants
p-benzoquinone carcinogenicity classification
Evaluation: No epidemiological data relevant to the carcinogenicity of 1,4-benzoquinone were available. There is inadequate evidence in experimental animals for the carcinogenicity of 1,4-benzoquinone. Overall evaluation: 1,4-Benzoquinone is not classifiable as to its carcinogenicity to humans (Group 3).
Source: Hazardous Substances Data Bank (HSDB)
An IARC group and a CLP classification answer different questions. IARC judges whether the evidence for cancer in humans is strong enough; CLP Annex VI is the legally binding EU classification. A substance can carry one and not the other.
p-benzoquinone occupational exposure limits
| Limit | Value | Source |
|---|---|---|
| PEL | 0.1 [ppm] | Haz-Map, Information on Hazardous Chemicals and Occupational Diseases |
| PEL | TWA 0.4 mg/m3 (0.1 ppm) | The National Institute for Occupational Safety and Health (NIOSH) |
| REL | TWA 0.4 mg/m3 (0.1 ppm) | The National Institute for Occupational Safety and Health (NIOSH) |
| IDLH | 100 mg/m3 (NIOSH, 2024) | CAMEO Chemicals |
| IDLH | 100 mg/cu m | Hazardous Substances Data Bank (HSDB) |
| IDLH | 100 mg/m3 | The National Institute for Occupational Safety and Health (NIOSH) |
These are United States values. The European Union sets its own indicative and binding limits, and the figure that applies at a given workplace is the one in the local regulation — not the one shown here.
08 · Physical and chemical properties
p-benzoquinone properties
Every value is shown with the conditions it was measured under and the source it came from. Where sources disagree, all values are listed rather than one being picked — the difference is usually a different form of the substance, not an error.
p-benzoquinone boiling point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | 180 °C (356 °F) | approximate | ICSC |
| Sublimes | sublimes | NIOSH | |
| SUBLIMES (NTP, 1992) | sublimes | CAMEO |
p-benzoquinone melting point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Melting point | 115.7 °C (240.3 °F) | HSDB | |
| 115.56 °C (240 °F) | NIOSH | ||
| 115.72 °C (240.3 °F) | CAMEO |
p-benzoquinone density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Density | 1.32 g/cm³ | NIOSH | |
| 1.318 g/cm³ | at 20 °C | HSDB |
p-benzoquinone solubility
| Property | Value | Conditions | Source |
|---|---|---|---|
| Solubility | SOL IN ALKALIES, HOT PETROLEUM ETHER | HSDB | |
| > 10% in ether | HSDB | ||
| > 10% in ethanol | HSDB |
p-benzoquinone vapor pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor pressure | 0.1 mmHg | at 25 °C | HSDB |
p-benzoquinone flash point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Flash point | 292.78 °C (559 °F) | CAMEO | |
| 65.56 °C (150 °F) | range, midpoint shown | HSDB |
p-benzoquinone autoignition temperature
| Property | Value | Conditions | Source |
|---|---|---|---|
| Autoignition temperature | 560 °C (1040 °F) | HSDB |
p-benzoquinone lower explosive limit (LEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Lower explosive limit (LEL) | Combustible Solid | NIOSH |
p-benzoquinone vapor density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor density | 3.7 (air = 1) | HSDB |
p-benzoquinone odor threshold
| Property | Value | Conditions | Source |
|---|---|---|---|
| Odor threshold | 0.4000 mg/cu m (low); 0.4000 mg/cu m (high); 2.00 mg/cu m (irritating concentration) | HSDB | |
| Odor Threshold Low: 0.1 [ppm] | Haz-Map | ||
| Odor Threshold High: 0.15 [ppm] | Haz-Map |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
09 · Fire and explosion
p-benzoquinone fire and explosion behaviour
These are descriptions rather than measured values, so they are kept out of the table above and quoted here with the source that reported them.
p-benzoquinone fire potential
Combustible.
Source: Hazardous Substances Data Bank (HSDB)
Fire and explosion
Drums containing moist quinone self heated, generating smoke and internal pressure. ... The moist material showed an exotherm at 40-50 °C and decomposed at 60-70 °C, ... owing to pressure impurities. Drums exposed to direct sunlight soon attain a surface temperature of 50-60 °C.
Source: HSDB
10 · Handling and storage
p-benzoquinone storage and handling
p-benzoquinone safe storage
Fireproof. Separated from combustible substances, reducing agents and food and feedstuffs. Cool. Dry.
Source: ILO-WHO International Chemical Safety Cards (ICSCs)
p-benzoquinone incompatible materials
Contact with strong oxidizers may cause fires & explosions.
Source: Hazardous Substances Data Bank (HSDB)
p-benzoquinone reactivity
BENZOQUINONE acts as an oxidizing agent (NTP, 1992).
Source: CAMEO Chemicals
Planning storage for a mix of chemicals? Check p-benzoquinone in the storage compatibility matrix →
11 · Questions
p-benzoquinone — frequently asked questions
What is the CAS number of p-benzoquinone?
The CAS number of p-benzoquinone is 106-51-4. Its EC number is 203-405-2.
What is the chemical formula of p-benzoquinone?
The molecular formula of p-benzoquinone is C6H4O2 and its molecular weight is 108.09 g/mol.
What does a p-benzoquinone label have to show?
Under CLP Annex VI the label for p-benzoquinone carries the pictograms Skull and crossbones and Environment and the signal word is Danger.
Is p-benzoquinone flammable?
CLP Annex VI assigns p-benzoquinone no flammability hazard class. That is not a statement that it cannot burn: the harmonised list only records the hazards that were assessed for it. The flash point reported for it is 292.78 °C (559 °F) (CAMEO).
Is p-benzoquinone a carcinogen?
CLP Annex VI records no harmonised carcinogenicity classification for p-benzoquinone. Annex VI is a list of agreed classifications, not a list of substances found safe, so this is an absence of a classification rather than a clean bill of health. IARC places it in Group 3: not classifiable as to its carcinogenicity to humans.
What is the exposure limit for p-benzoquinone?
The US occupational exposure limit reported for p-benzoquinone is 0.1 [ppm] (Haz-Map, Information on Hazardous Chemicals and Occupational Diseases). Limits differ by country: the EU sets its own indicative and binding values, and the figure that applies at a given workplace is the one in the local regulation.
What is the boiling point of p-benzoquinone?
The boiling point reported for p-benzoquinone is 180 °C (356 °F), approximate (ICSC).
What is the melting point of p-benzoquinone?
The melting point reported for p-benzoquinone is 115.7 °C (240.3 °F) (HSDB).
Nearby
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