Substance profile
Cyclopentane
Cyclopentane is a colorless liquid with a mild, sweet odor.
01 · Identification
What Cyclopentane is
Cyclopentane is a colorless liquid with a mild, sweet odor. Its molecular formula is C5H10 and its molecular weight is 70.13 g/mol. It boils at 49.2 °C, melts at -93.4 °C.
Under the GHS it carries the signal word Danger. It is classed as flammable agents - 3rd degree.
02 · Identifiers
Cyclopentane identifiers and molecular data
Cyclopentane CAS number and EC number
Cyclopentane molecular formula and molecular weight
03 · GHS classification
Cyclopentane hazard classification
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
Cyclopentane pictograms and signal word
Cyclopentane hazard class and category
| Hazard class | Category | From code | Pictogram |
|---|---|---|---|
| Flammable liquids GHS chapter 2.6 | Category 2 | H225 | GHS02 |
| Hazardous to the aquatic environment - chronic GHS chapter 4.1 | Category 3 | H412 | — |
Cyclopentane hazard statements (H-codes)
| Code | Hazard statement |
|---|---|
| H225 | Highly flammable liquid and vapour. |
| H412 | Harmful to aquatic life with long lasting effects. |
This page lists only the codes assigned to Cyclopentane. 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 Cyclopentane
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 Cyclopentane 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
Cyclopentane precautionary statements
CLP Annex VI assigns 7 precautionary statements to Cyclopentane. 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.
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
Cyclopentane 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 | циклопентан |
| Spanish español | Ciclopentano |
| Czech čeština | cyklopentan |
| Danish dansk | cyclopentan |
| German Deutsch | Cyclopentan |
| Estonian eesti | tsüklopentaan |
| Greek ελληνικά | κυκλοπεντάνιο |
| English English | cyclopentane |
| French français | cyclopentane |
| Croatian hrvatski | ciklopentan |
| Italian italiano | ciclopentano |
| Latvian latviešu | ciklopentāns |
| Lithuanian lietuvių | ciklopentanas |
| Hungarian magyar | ciklopentán |
| Maltese Malti | ċiklopentan |
| Dutch Nederlands | cyclopentaan |
| Polish polski | cyklopentan |
| Portuguese português | ciclopentano |
| Romanian română | ciclopentan |
| Slovak slovenčina | cyklopentán |
| Slovenian slovenščina | ciklopentan |
| Finnish suomi | syklopentaani |
| Swedish svenska | cyklopentan |
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
Cyclopentane GHS label elements
Everything CLP Annex VI fixes for Cyclopentane, laid out the way it appears on a label. The greyed lines are the parts only the supplier can fill in.
Danger
Cyclopentane
- Highly flammable liquid and vapour.
- Harmful to aquatic life with long lasting effects.
- 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.
- Avoid release to the environment.
- Store in a well-ventilated place.
- Dispose of contents/container to …
Supplier name, address and telephone number· Product identifier·Nominal quantity
Need this as an actual label? Open Cyclopentane in the GHS label constructor →
07 · Health hazards
Cyclopentane health hazards and exposure limits
Cyclopentane hazard summary
Causes central nervous system depression in acute animal studies; 2021 ACGIH Basis: central nervous system impairment; Explosion hazard; [ACGIH] A skin, eye, and respiratory tract irritant; [ICSC]
Source: Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
Cyclopentane occupational exposure limits
| Limit | Value | Source |
|---|---|---|
| PEL | none See Appendix G | The National Institute for Occupational Safety and Health (NIOSH) |
| REL | 600 ppm (1720 mg/m³) | Occupational Safety and Health Administration (OSHA) |
| REL | TWA 600 ppm (1720 mg/m3) | The National Institute for Occupational Safety and Health (NIOSH) |
| IDLH | N.D. | 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
Cyclopentane 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.
Cyclopentane boiling point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | 49.2 °C (120.6 °F) | HSDB | |
| 49.44 °C (121 °F) | NIOSH | ||
| 49.28 °C (120.7 °F) | at 760 mmHg | CAMEO |
Cyclopentane melting point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Melting point | -93.4 °C (-136.1 °F) | HSDB | |
| -93.89 °C (-137 °F) | NIOSH |
Cyclopentane density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Density | 0.75 g/cm³ | NIOSH | |
| 0.7457 g/cm³ | at 20 °C | HSDB | |
| 0.74 g/cm³ | at 20 °C | CAMEO |
Cyclopentane solubility
| Property | Value | Conditions | Source |
|---|---|---|---|
| Solubility | Miscible with other hydrocarbon solvents, alcohol, ether | HSDB | |
| Miscible with ethanol, ethyl ether, acetone, benzene, petroleum ether, carbon tetrachloride | HSDB | ||
| In water, 156 ppm at 25 °C | at 25 °C | HSDB |
Cyclopentane vapor pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor pressure | 337.528 mmHg | at 20 °C | ICSC |
| 317.8 mmHg | at 25 °C | HSDB |
Cyclopentane flash point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Flash point | -20 °C (-4 °F) | HSDB | |
| -37.22 °C (-35 °F) | NIOSH | ||
| -37 °C (-34.6 °F) | ICSC |
Cyclopentane autoignition temperature
| Property | Value | Conditions | Source |
|---|---|---|---|
| Autoignition temperature | 361.11 °C (682 °F) | HSDB | |
| 320 °C (608 °F) | ICSC |
Cyclopentane lower explosive limit (LEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Lower explosive limit (LEL) | 1.1 % by volume | NIOSH | |
| 1.1 % by volume | approx. | CAMEO |
Cyclopentane upper explosive limit (UEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Upper explosive limit (UEL) | 8.7 % by volume | HSDB | |
| 8.7 % by volume | approx. | CAMEO |
Cyclopentane vapor density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor density | 2.42 (air = 1) | HSDB | |
| 2.4 (air = 1) | ICSC |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
09 · Fire and explosion
Cyclopentane 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.
Cyclopentane fire potential
Flammable, dangerous fire risk.
Source: Hazardous Substances Data Bank (HSDB)
10 · Handling and storage
Cyclopentane storage and handling
Cyclopentane safe storage
Fireproof. Well closed. Separated from strong oxidants and food and feedstuffs. Store in an area without drain or sewer access. Provision to contain effluent from fire extinguishing.
Source: ILO-WHO International Chemical Safety Cards (ICSCs)
Cyclopentane storage conditions
Conditions for safe storage, including any incompatibilities: Keep container tightly closed in a dry and well-ventilated place. Containers which are opened must be carefully resealed and kept upright to prevent leakage.
Source: Hazardous Substances Data Bank (HSDB)
Cyclopentane incompatible materials
Strong oxidizers (e.g. chlorine, bromine, fluorine).
Source: Hazardous Substances Data Bank (HSDB)
Cyclopentane reactivity
CYCLOPENTANE is incompatible with strong oxidizing agents such as chlorine, bromine, fluorine. (NIOSH, 2024).
Source: CAMEO Chemicals
Planning storage for a mix of chemicals? Check Cyclopentane in the storage compatibility matrix →
11 · Transport
Cyclopentane 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.
Cyclopentane under UN 1146 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| CYCLOPENTANE | 3 | F1 | II | |
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) |
|---|---|---|---|
| Cyclopentane | 3 | II | |
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
Cyclopentane — frequently asked questions
What is the CAS number of Cyclopentane?
The CAS number of Cyclopentane is 287-92-3. Its EC number is 206-016-6.
What is the chemical formula of Cyclopentane?
The molecular formula of Cyclopentane is C5H10 and its molecular weight is 70.13 g/mol.
What does a Cyclopentane label have to show?
Under CLP Annex VI the label for Cyclopentane carries the pictogram Flame and the signal word is Danger.
Is Cyclopentane flammable?
Yes. CLP Annex VI assigns Cyclopentane H225 — highly flammable liquid and vapour. The flash point reported for it is -20 °C (-4 °F) (HSDB).
Is Cyclopentane a carcinogen?
CLP Annex VI records no harmonised carcinogenicity classification for Cyclopentane. 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 exposure limit for Cyclopentane?
The US occupational exposure limit reported for Cyclopentane is none See Appendix G (The National Institute for Occupational Safety and Health (NIOSH)). 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 Cyclopentane?
The boiling point reported for Cyclopentane is 49.2 °C (120.6 °F) (HSDB).
What is the melting point of Cyclopentane?
The melting point reported for Cyclopentane is -93.4 °C (-136.1 °F) (HSDB).
How should Cyclopentane be stored?
CLP Annex VI assigns Cyclopentane the storage statement P403. Conditions for safe storage, including any incompatibilities: Keep container tightly closed in a dry and well-ventilated place. Containers which are opened must be carefully resealed and kept upright to prevent leakage. (Hazardous Substances Data Bank (HSDB))
Nearby
Substances next to Cyclopentane
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