Substance profile
Cyclopentanone
Cyclopentanone is a water-white, mobile liquid with a distinctive ethereal odor, somewhat like peppermint.
01 · Identification
What Cyclopentanone is
Cyclopentanone is a water-white, mobile liquid with a distinctive ethereal odor, somewhat like peppermint. Its molecular formula is C5H8O and its molecular weight is 84.12 g/mol. It boils at 131 °C, melts at -51.3 °C.
Under the GHS it carries the signal word Warning. It is classed as flammable agents - 3rd degree.
02 · Identifiers
Cyclopentanone identifiers and molecular data
Cyclopentanone CAS number and EC number
Cyclopentanone molecular formula and molecular weight
03 · GHS classification
Cyclopentanone hazard classification
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
Cyclopentanone pictograms and signal word
Cyclopentanone hazard class and category
| Hazard class | Category | From code | Pictogram |
|---|---|---|---|
| Flammable liquids GHS chapter 2.6 | Category 3 | H226 | GHS02 |
| Skin corrosion/irritation GHS chapter 3.2 | Category 2 | H315 | GHS07 |
| Serious eye damage/eye irritation GHS chapter 3.3 | Category 2A | H319 | GHS07 |
Cyclopentanone hazard statements (H-codes)
| Code | Hazard statement |
|---|---|
| H226 | Flammable liquid and vapour. |
| H315 | Causes skin irritation. |
| H319 | Causes serious eye irritation. |
This page lists only the codes assigned to Cyclopentanone. 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 Cyclopentanone
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 Cyclopentanone 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
Cyclopentanone precautionary statements
CLP Annex VI assigns 14 precautionary statements to Cyclopentanone. 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.
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
Cyclopentanone 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 | циклопентанон |
| Spanish español | Ciclopentanona |
| Czech čeština | cyklopentanon |
| Danish dansk | cyclopentanon |
| German Deutsch | Cyclopentanon |
| Estonian eesti | tsüklopentanoon |
| Greek ελληνικά | κυκλοπεντανόνη |
| English English | cyclopentanone |
| French français | cyclopentanone |
| Croatian hrvatski | ciklopentanon |
| Italian italiano | ciclopentanone |
| Latvian latviešu | ciklopentanons |
| Lithuanian lietuvių | ciklopentanonas |
| Hungarian magyar | ciklopentanon |
| Maltese Malti | ċiklopentanon |
| Dutch Nederlands | cyclopentanon |
| Polish polski | cyklopentanon |
| Portuguese português | ciclopentanona |
| Romanian română | ciclopentanonă |
| Slovak slovenčina | cyklopentanón |
| Slovenian slovenščina | ciklopentanon |
| Finnish suomi | syklopentanoni |
| Swedish svenska | cyklopentanon |
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
Cyclopentanone GHS label elements
Everything CLP Annex VI fixes for Cyclopentanone, laid out the way it appears on a label. The greyed lines are the parts only the supplier can fill in.
Warning
Cyclopentanone
- Flammable liquid and vapour.
- Causes skin irritation.
- Causes serious eye irritation.
- Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking.
- Keep container tightly closed.
- Use explosion-proof [electrical/ventilating/lighting/…] equipment.
- Use only non-sparking tools.
- Wash … thoroughly after handling.
- Wear protective gloves/protective clothing/eye protection/face protection/hearing protection/…
- IF ON SKIN:
- IF IN EYES:
- Get medical advice/attention.
- If skin irritation occurs:
- If eye irritation persists:
- Remove contact lenses, if present and easy to do. Continue rinsing.
- Wash with plenty of water/…
- Store in a well-ventilated place.
Supplier name, address and telephone number· Product identifier·Nominal quantity
Need this as an actual label? Open Cyclopentanone in the GHS label constructor →
07 · Health hazards
Cyclopentanone health hazards and exposure limits
Cyclopentanone hazard summary
The major hazards encountered in the use and handling of cyclopentanone stem from its toxicologic properties and flammability. Toxic by all routes (ie, inhalation, ingestion, and dermal absorption), exposure to this peppermint-smelling, water-white liquid may occur from its production and use as an intermediate for pharmaceuticals, biologicals, insecticides, and rubber chemicals. Effects from exposure may include contact burns to the skin and eyes, CNS depression, and suffocation. In activities and situations where over-exposure may occur, wear protective clothing and a positive pressure self-contained breathing apparatus. If contact should occur, irrigate exposed eyes with copious amounts of tepid water for at least 15 minutes and wash exposed skin thoroughly with soap and water. Contaminated clothing and shoes should be removed and isolated at the site. Cyclopentanone may be ignited by heat, sparks, or flames (flash point: 87 °F, closed cup), and is dangerously reactive with oxidizing materials. Its heavier-than-air vapor may travel to a source of ignition and flash back, or accumulate to explosive concentrations in confined spaces such as sewers. Also, containers of this substance may explode in the heat of a fire. For fires involving cyclopentanone, extinguish with dry chemical, CO2, water spray, fog, or alcohol-resistant foam. Isolate the area for 1/2 mile in all directions if a tank, rail car, or tank truck is involved in the fire. For small spills of cyclopentanone, take up with sand or other noncombustible absorbent and place into containers for later disposal. Large spills should first be diked far ahead of the spill.
Source: Hazardous Substances Data Bank (HSDB)
08 · Physical and chemical properties
Cyclopentanone 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.
Cyclopentanone boiling point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | 130.6 °C (267.1 °F) | at 760 mmHg | HSDB |
| 130.65 °C (267.2 °F) | at 760 mmHg | CAMEO | |
| 131 °C (267.8 °F) | ICSC |
Cyclopentanone melting point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Melting point | -51.3 °C (-60.3 °F) | HSDB | |
| -51.28 °C (-60.3 °F) | CAMEO | ||
| -51 °C (-59.8 °F) | ICSC |
Cyclopentanone density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Density | 0.95 g/cm³ | ICSC | |
| 0.9487 g/cm³ | at 20 °C | HSDB |
Cyclopentanone solubility
| Property | Value | Conditions | Source |
|---|---|---|---|
| Solubility | Sol in alcohol, acetone, ether | HSDB | |
| Estimated water solubility of 9175 mg/l | HSDB | ||
| Solubility in water: poor | ICSC |
Cyclopentanone vapor pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor pressure | 11.4 mmHg | at 25 °C | HSDB |
| 11.4 mmHg | Haz-Map |
Cyclopentanone flash point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Flash point | 30.56 °C (87 °F) | HSDB | |
| 30 °C (86 °F) | CAMEO | ||
| 26 °C (78.8 °F) | ICSC |
Cyclopentanone vapor density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor density | 2.3 (air = 1) | HSDB |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
09 · Fire and explosion
Cyclopentanone 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.
Cyclopentanone fire potential
DANGEROUS WHEN EXPOSED TO FLAME; CAN REACT WITH OXIDIZING MATERIALS.
Source: Hazardous Substances Data Bank (HSDB)
10 · Handling and storage
Cyclopentanone storage and handling
Cyclopentanone peroxide formation
D*: Other compounds that may form peroxides
Source: Lab and Research Safety, University of Minnesota
Cyclopentanone safe storage
Fireproof. Separated from acids. Cool. Keep in the dark. Keep in a well-ventilated room. Store only if stabilized.
Source: ILO-WHO International Chemical Safety Cards (ICSCs)
Cyclopentanone reactivity
CYCLOPENTANONE polymerizes easily, especially in the presence of acids. Can react with oxidizing materials, i.e. hydrogen peroxide. (NTP, 1992)
Source: CAMEO Chemicals
Planning storage for a mix of chemicals? Check Cyclopentanone in the storage compatibility matrix →
11 · Transport
Cyclopentanone UN number and transport classification
Transport classification is a separate system from the GHS classification above. It decides how a package is marked and how a load may be carried; it does not follow from the workplace label, and the workplace label does not follow from it. The entries below are linked by CAS number, never by name.
Cyclopentanone under UN 2245 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| CYCLOPENTANONE | 3 | F1 | III | |
Source: ADR 2025, Table A of Chapter 3.2 · ECE/TRANS/352 Vol. I (UNECE). Class 3 is “Flammable liquids” (ADR 2.1.1.1).
United States · 49 CFR 172.101 Hazardous Materials Table
| Proper shipping name (column 2) | Class or division | PG | Labels (column 6) |
|---|---|---|---|
| Cyclopentanone | 3 | III | |
Source: 49 CFR 172.101 Hazardous Materials Table · eCFR, revision 2026-08-03. Class 3 is “Flammable and combustible liquid” (49 CFR 173.2).
12 · Questions
Cyclopentanone — frequently asked questions
What is the CAS number of Cyclopentanone?
The CAS number of Cyclopentanone is 120-92-3. Its EC number is 204-435-9.
What is the chemical formula of Cyclopentanone?
The molecular formula of Cyclopentanone is C5H8O and its molecular weight is 84.12 g/mol.
What does a Cyclopentanone label have to show?
Under CLP Annex VI the label for Cyclopentanone carries the pictograms Flame and Exclamation mark and the signal word is Warning.
Is Cyclopentanone flammable?
Yes. CLP Annex VI assigns Cyclopentanone H226 — flammable liquid and vapour. The flash point reported for it is 30.56 °C (87 °F) (HSDB).
Is Cyclopentanone a carcinogen?
CLP Annex VI records no harmonised carcinogenicity classification for Cyclopentanone. 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.
What is the boiling point of Cyclopentanone?
The boiling point reported for Cyclopentanone is 130.6 °C (267.1 °F), at 760 mmHg (HSDB).
What is the melting point of Cyclopentanone?
The melting point reported for Cyclopentanone is -51.3 °C (-60.3 °F) (HSDB).
How should Cyclopentanone be stored?
CLP Annex VI assigns Cyclopentanone the storage statement P403.
Nearby
Substances next to Cyclopentanone
Keep going: substances starting with C, or search the whole database by name, CAS number, pictogram or signal word.