Substance profile
Ethanethiol
Ethanethiol is a colorless liquid with a leek-like odor.
01 · Identification
What Ethanethiol is
Ethanethiol is a colorless liquid with a leek-like odor. Its molecular formula is C2H6S and its molecular weight is 62.14 g/mol. It boils at 35.1 °C, melts at -148 °C, is soluble in water.
Under the GHS it carries the signal word Danger. It is classed as flammable agents - 4th degree.
02 · Identifiers
Ethanethiol identifiers and molecular data
Ethanethiol CAS number and EC number
Ethanethiol molecular formula and molecular weight
Other names for Ethanethiol
- ethyl mercaptan
03 · GHS classification
Ethanethiol hazard classification
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
Ethanethiol pictograms and signal word
Ethanethiol hazard class and category
| Hazard class | Category | From code | Pictogram |
|---|---|---|---|
| Flammable liquids GHS chapter 2.6 | Category 1 | H224 | GHS02 |
| Acute toxicity - oral GHS chapter 3.1 | Category 4 | H302 | GHS07 |
| Acute toxicity - inhalation GHS chapter 3.1 | Category 3 | H331 | GHS06 |
| Hazardous to the aquatic environment - acute GHS chapter 4.1 | Category 1 | H400 | GHS09 |
| Hazardous to the aquatic environment - chronic GHS chapter 4.1 | Category 1 | H410 | GHS09 |
Ethanethiol hazard statements (H-codes)
| Code | Hazard statement |
|---|---|
| H224 | Extremely flammable liquid and vapour. |
| H331 | Toxic if inhaled. |
| H302 | Harmful if swallowed. |
| H400 | Very toxic to aquatic life. |
| H410 | Very toxic to aquatic life with long lasting effects. |
This page lists only the codes assigned to Ethanethiol. 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 Ethanethiol
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 Ethanethiol 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
Ethanethiol precautionary statements
CLP Annex VI assigns 16 precautionary statements to Ethanethiol. 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
Ethanethiol 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 | етантиол етилмеркаптан |
| Spanish español | Etanotiol etilmercaptano |
| Czech čeština | ethanthiol ethylmerkaptan |
| Danish dansk | ethanethiol ethylmercaptan |
| German Deutsch | Ethanethiol Ethylmercaptan |
| Estonian eesti | etaantiool etüülmerkaptaan |
| Greek ελληνικά | αιθανοθειόλη αιθυλομερκαπτάνη |
| English English | ethanethiol ethyl mercaptan |
| French français | éthanethiol éthylmercaptan |
| Croatian hrvatski | etantiol etil-merkaptan |
| Italian italiano | etantiolo etilmercaptano |
| Latvian latviešu | etāntiols etilmerkaptāns |
| Lithuanian lietuvių | etantiolis etilmerkaptanas |
| Hungarian magyar | etántiol etil-merkaptán |
| Maltese Malti | etanetjol merkaptan tal-etil |
| Dutch Nederlands | ethaanthiol ethylmercaptaan |
| Polish polski | etanotiol merkaptan etylowy |
| Portuguese português | etanotiol etilmercaptano |
| Romanian română | etantiol etilmercaptan |
| Slovak slovenčina | etántiol etylsulfán |
| Slovenian slovenščina | etantiol etil merkaptan |
| Finnish suomi | etaanitioli etyylimerkaptaani |
| Swedish svenska | etantiol etylmerkaptan |
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
Ethanethiol GHS label elements
Everything CLP Annex VI fixes for Ethanethiol, laid out the way it appears on a label. The greyed lines are the parts only the supplier can fill in.
Danger
Ethanethiol
- Extremely flammable liquid and vapour.
- Toxic if inhaled.
- Harmful if swallowed.
- Very toxic to aquatic life.
- Very toxic 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.
- Do not breathe dust/fume/gas/mist/vapours/spray.
- Do not eat, drink or smoke when using this product.
- Use only outdoors or in a well-ventilated area.
- Avoid release to the environment.
- IF SWALLOWED:
- IF INHALED:
- Immediately call a POISON CENTER/doctor/…
- Call a POISON CENTER/doctor/… if you feel unwell.
- Rinse mouth.
- Collect spillage.
- 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 Ethanethiol in the GHS label constructor →
07 · Health hazards
Ethanethiol health hazards and exposure limits
Ethanethiol hazard summary
Its toxicity in rats and mice is similar to that of butyl mercaptan. Acutely, it is about 1/5 as toxic as hydrogen sulfide. Human volunteers exposed to 1mg/m3 (0.5 ppm) experienced no symptoms, while those exposed to 10 mg/m3 (4 ppm) complained of mucous membrane irritation and fatigue. [ACGIH] Liver necrosis occurs in animals receiving sublethal doses. [HSDB] See THIOLS.
Source: Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
Ethanethiol occupational exposure limits
| Limit | Value | Source |
|---|---|---|
| PEL | 10 ppm (25 mg/m³) | Occupational Safety and Health Administration (OSHA) |
| PEL | C 10 ppm (25 mg/m3) See Appendix G | The National Institute for Occupational Safety and Health (NIOSH) |
| REL | 0.5 ppm (1.3 mg/m³) [15 minutes] | Occupational Safety and Health Administration (OSHA) |
| REL | C 0.5 ppm (1.3 mg/m3) [15-minute] | The National Institute for Occupational Safety and Health (NIOSH) |
| IDLH | 500 ppm (NIOSH, 2024) | CAMEO Chemicals |
| IDLH | 500.0 [ppm] | Haz-Map, Information on Hazardous Chemicals and Occupational Diseases |
| IDLH | 500 ppm | Hazardous Substances Data Bank (HSDB) |
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
Ethanethiol 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.
Ethanethiol boiling point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | 35.1 °C (95.2 °F) | HSDB | |
| 30.46 °C (86.8 °F) | HSDB | ||
| 35 °C (95 °F) | NIOSH |
Ethanethiol melting point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Melting point | -147.8 °C (-234 °F) | HSDB | |
| -144.44 °C (-228 °F) | NIOSH | ||
| -147.78 °C (-234 °F) | CAMEO |
Ethanethiol density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Density | 0.84 g/cm³ | NIOSH | |
| 0.826 g/cm³ | at 20 °C | CAMEO | |
| 0.8315 g/cm³ | at 25 °C | HSDB |
Ethanethiol solubility
| Property | Value | Conditions | Source |
|---|---|---|---|
| Solubility | Soluble in alcohol, ether, petroleum naphtha | HSDB | |
| Soluble in acetone, dilute alkali | HSDB | ||
| In water, 15,603 mg/L at 25 °C | at 25 °C | HSDB |
Ethanethiol vapor pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor pressure | 442 mmHg | NIOSH | |
| 529 mmHg | at 25 °C, Extrapolated | HSDB |
Ethanethiol flash point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Flash point | -48.3 °C (-54.9 °F) | Closed cup | HSDB |
| -54 °C (-65.2 °F) | Closed cup | HSDB | |
| -48.33 °C (-55 °F) | NIOSH |
Ethanethiol autoignition temperature
| Property | Value | Conditions | Source |
|---|---|---|---|
| Autoignition temperature | 298.9 °C (570 °F) | HSDB | |
| 300 °C (572 °F) | CAMEO | ||
| 299 °C (570.2 °F) | ICSC |
Ethanethiol lower explosive limit (LEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Lower explosive limit (LEL) | 2.8 % by volume | HSDB |
Ethanethiol upper explosive limit (UEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Upper explosive limit (UEL) | 18 % by volume | HSDB |
Ethanethiol vapor density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor density | 2.14 (air = 1) | HSDB |
Ethanethiol odor threshold
| Property | Value | Conditions | Source |
|---|---|---|---|
| Odor threshold | An odor threshold of 0.00076 ppm has been reported. | HSDB | |
| Minimum detectable concentration= 1 part in 50 billion parts of air. | HSDB | ||
| 0.0003 PPM | HSDB |
Ethanethiol critical temperature and pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Critical temperature and pressure | 225.5 °C (437.9 °F) | HSDB |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
09 · Fire and explosion
Ethanethiol 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.
Ethanethiol fire potential
Dangerous, when exposed to heat or flame or oxidizers.
Source: Hazardous Substances Data Bank (HSDB)
10 · Handling and storage
Ethanethiol storage and handling
Ethanethiol safe storage
Fireproof. Separated from strong oxidants and strong acids. Cool.
Source: ILO-WHO International Chemical Safety Cards (ICSCs)
Ethanethiol storage conditions
Fireproof. Separated from strong oxidants, strong acids. Cool.
Source: Hazardous Substances Data Bank (HSDB)
Ethanethiol incompatible materials
Strong oxidizers [Note: Reacts violently with calcium hypochlorite].
Source: Hazardous Substances Data Bank (HSDB)
Ethanethiol reactivity
ETHYL MERCAPTAN reacts violently with calcium hypochlorite, May react vigorously with other oxidizing reagents. On contact with strong acids or when heated to decomposition it emits highly toxic fumes of sulfur oxides [Sax, 9th ed., 1996, p. 1575].
Source: CAMEO Chemicals
Planning storage for a mix of chemicals? Check Ethanethiol in the storage compatibility matrix →
11 · Transport
Ethanethiol 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.
Ethanethiol under UN 2363 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| ETHYL MERCAPTAN | 3 | F1 | I | |
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) |
|---|---|---|---|
| Ethyl mercaptan | 3 | I | |
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
Ethanethiol — frequently asked questions
What is the CAS number of Ethanethiol?
The CAS number of Ethanethiol is 75-08-1. Its EC number is 200-837-3.
What is the chemical formula of Ethanethiol?
The molecular formula of Ethanethiol is C2H6S and its molecular weight is 62.14 g/mol.
What does a Ethanethiol label have to show?
Under CLP Annex VI the label for Ethanethiol carries the pictograms Flame, Skull and crossbones and Environment and the signal word is Danger.
Is Ethanethiol flammable?
Yes. CLP Annex VI assigns Ethanethiol H224 — extremely flammable liquid and vapour. The flash point reported for it is -48.3 °C (-54.9 °F), Closed cup (HSDB).
Is Ethanethiol a carcinogen?
CLP Annex VI records no harmonised carcinogenicity classification for Ethanethiol. 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 Ethanethiol?
The US occupational exposure limit reported for Ethanethiol is 10 ppm (25 mg/m³) (Occupational Safety and Health Administration (OSHA)). 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 Ethanethiol?
The boiling point reported for Ethanethiol is 35.1 °C (95.2 °F) (HSDB).
What is the melting point of Ethanethiol?
The melting point reported for Ethanethiol is -147.8 °C (-234 °F) (HSDB).
How should Ethanethiol be stored?
CLP Annex VI assigns Ethanethiol the storage statement P403. Fireproof. Separated from strong oxidants, strong acids. Cool. (Hazardous Substances Data Bank (HSDB))
Nearby
Substances next to Ethanethiol
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