Substance profile
Acetaldehyde
Acetaldehyde is a volatile liquid or gas with a pungent, fruity odor.
01 · Identification
What Acetaldehyde is
Acetaldehyde is a volatile liquid or gas with a pungent, fruity odor. Its molecular formula is C2H4O and its molecular weight is 44.05 g/mol. It boils at 20.8 °C, melts at -123 °C, is miscible with water.
Under the GHS it carries the signal word Danger. It is classed as hazardous Air Pollutants (HAPs).
02 · Identifiers
Acetaldehyde identifiers and molecular data
Acetaldehyde CAS number and EC number
Acetaldehyde molecular formula and molecular weight
Other names for Acetaldehyde
- ethanal
03 · GHS classification
Acetaldehyde hazard classification
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
Acetaldehyde pictograms and signal word
Acetaldehyde hazard class and category
| Hazard class | Category | From code | Pictogram |
|---|---|---|---|
| Flammable liquids GHS chapter 2.6 | Category 1 | H224 | GHS02 |
| Serious eye damage/eye irritation GHS chapter 3.3 | Category 2A | H319 | GHS07 |
| Germ cell mutagenicity GHS chapter 3.5 | Category 2 | H341 | GHS08 |
| Carcinogenicity GHS chapter 3.6 | Category 1A or 1B | H350 | GHS08 |
| Specific target organ toxicity - single exposure GHS chapter 3.8 | Category 3 | H335 | GHS07 |
Where two values are shown with “or”, the hazard statement is shared by more than one category or by more than one class, and the code alone does not say which. H272, for example, belongs to oxidising liquids and to oxidising solids — the physical state decides. The binding answer for a specific entry is in the CLP Annex VI table itself.
Acetaldehyde hazard statements (H-codes)
| Code | Hazard statement |
|---|---|
| H224 | Extremely flammable liquid and vapour. |
| H350 | May cause cancer <state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard>. |
| H341 | Suspected of causing genetic defects <state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard>. |
| H335 | May cause respiratory irritation. |
| H319 | Causes serious eye irritation. |
This page lists only the codes assigned to Acetaldehyde. 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 Acetaldehyde
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 Acetaldehyde 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
Acetaldehyde precautionary statements
CLP Annex VI assigns 13 precautionary statements to Acetaldehyde. 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
Acetaldehyde 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 | ацеталдехид етанал |
| Spanish español | Acetaldehído etanal |
| Czech čeština | acetaldehyd ethanal |
| Danish dansk | acetaldehyd ethanal |
| German Deutsch | Acetaldehyd Ethanal |
| Estonian eesti | atseetaldehüüd etanaal |
| Greek ελληνικά | ακεταλδεΰδη αιθανάλη |
| English English | acetaldehyde ethanal |
| French français | acétaldéhyde éthanal |
| Croatian hrvatski | acetaldehid etanal |
| Italian italiano | acetaldeide etanale |
| Latvian latviešu | acetaldehīds etanāls |
| Lithuanian lietuvių | acetaldehidas etanalis |
| Hungarian magyar | acetaldehid etanal |
| Maltese Malti | aċetaldeid etanal |
| Dutch Nederlands | aceetaldehyde ethanal |
| Polish polski | acetaldehyd aldehyd octowy etanal |
| Portuguese português | acetaldeído etanal |
| Romanian română | acetaldehidă etanal |
| Slovak slovenčina | acetaldehyd etanal |
| Slovenian slovenščina | Acetaldehid etanal |
| Finnish suomi | asetaldehydi etanaali |
| Swedish svenska | acetaldehyd etanal |
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
Acetaldehyde GHS label elements
Everything CLP Annex VI fixes for Acetaldehyde, laid out the way it appears on a label. The greyed lines are the parts only the supplier can fill in.
Danger
Acetaldehyde
- Extremely flammable liquid and vapour.
- May cause cancer <state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard>.
- Suspected of causing genetic defects <state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard>.
- May cause respiratory irritation.
- Causes serious eye irritation.
- Obtain special instructions before use.
- 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 IN EYES:
- IF exposed or concerned:
- Get medical advice/attention.
- If eye irritation persists:
- Remove contact lenses, if present and easy to do. Continue rinsing.
- Store in a well-ventilated place.
Supplier name, address and telephone number· Product identifier·Nominal quantity
Need this as an actual label? Open Acetaldehyde in the GHS label constructor →
07 · Health hazards
Acetaldehyde health hazards and exposure limits
Acetaldehyde hazard summary
Acetaldehyde is mainly used as an intermediate in the synthesis of other chemicals. It is ubiquitous in the environment and may be formed in the body from the breakdown of ethanol. Acute (short-term) exposure to acetaldehyde results in effects including irritation of the eyes, skin, and respiratory tract. Symptoms of chronic (long-term) intoxication of acetaldehyde resemble those of alcoholism. Acetaldehyde is considered a probable human carcinogen (Group B2) based on inadequate human cancer studies and animal studies that have shown nasal tumors in rats and laryngeal tumors in hamsters.
Source: EPA Hazardous Air Pollutants
Acetaldehyde carcinogenicity classification
Acetaldehyde is reasonably anticipated to be a human carcinogen based on sufficient evidence of carcinogenicity from studies in experimental animals.
Source: Hazardous Substances Data Bank (HSDB)
Evaluation: There is inadequate evidence in humans for the carcinogenicity of acetaldehyde. There is sufficient evidence in experimental animals for the carcinogenicity of acetaldehyde. Overall evaluation: Acetaldehyde is possibly carcinogenic to humans (Group 2B).
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.
Acetaldehyde occupational exposure limits
| Limit | Value | Source |
|---|---|---|
| PEL | 200.0 [ppm] | Haz-Map, Information on Hazardous Chemicals and Occupational Diseases |
| PEL | 200 ppm (360 mg/m³) | Occupational Safety and Health Administration (OSHA) |
| PEL | TWA 200 ppm (360 mg/m³) See Appendix G | The National Institute for Occupational Safety and Health (NIOSH) |
| REL | Ca See Appendix ASee Appendix C (Aldehydes) | The National Institute for Occupational Safety and Health (NIOSH) |
| IDLH | 2000 ppm ; A potential occupational carcinogen. (NIOSH, 2024) | CAMEO Chemicals |
| IDLH | 2000.0 [ppm] | Haz-Map, Information on Hazardous Chemicals and Occupational Diseases |
| IDLH | NIOSH considers acetaldehyde to be a potential occupational carcinogen. | 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
Acetaldehyde 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.
Acetaldehyde boiling point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | 20.8 °C (69.4 °F) | HSDB | |
| 20.56 °C (69 °F) | NIOSH | ||
| 21.11 °C (70 °F) | at 760 mmHg | CAMEO |
Acetaldehyde melting point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Melting point | -123.4 °C (-190.1 °F) | HSDB | |
| -123.33 °C (-190 °F) | NIOSH | ||
| -123.5 °C (-190.3 °F) | CAMEO |
Acetaldehyde density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Density | 0.79 g/cm³ | NIOSH | |
| 0.78 g/cm³ | at 20 °C | CAMEO | |
| 0.7834 g/cm³ | at 18 °C | HSDB |
Acetaldehyde solubility
| Property | Value | Conditions | Source |
|---|---|---|---|
| Solubility | Miscible with ethanol, ether, benzene; slightly soluble in chloroform | HSDB | |
| Miscible with water /1X10+6 mg/L at 25 °C/ | at 25 °C | HSDB |
Acetaldehyde vapor pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor pressure | 740 mmHg | NIOSH | |
| 757.562 mmHg | at 20 °C | ICSC | |
| 902 mmHg | at 25 °C | HSDB |
Acetaldehyde flash point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Flash point | -40 °C (-40 °F) | HSDB | |
| -38.89 °C (-38 °F) | Closed cup | HSDB | |
| -37.78 °C (-36 °F) | NIOSH |
Acetaldehyde autoignition temperature
| Property | Value | Conditions | Source |
|---|---|---|---|
| Autoignition temperature | 175 °C (347 °F) | HSDB | |
| 185 °C (365 °F) | CAMEO |
Acetaldehyde lower explosive limit (LEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Lower explosive limit (LEL) | 4 % by volume | HSDB |
Acetaldehyde upper explosive limit (UEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Upper explosive limit (UEL) | 60 % by volume | HSDB | |
| 60 % by volume | From table | HSDB |
Acetaldehyde vapor density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor density | 1.52 (air = 1) | HSDB | |
| 1.5 (air = 1) | ICSC |
Acetaldehyde odor threshold
| Property | Value | Conditions | Source |
|---|---|---|---|
| Odor threshold | Recognition in air= 2.1x10-1 ppm (chemically pure) | HSDB | |
| Odor low: 0.0002 mg/cu m; Odor high: 4.14 mg/cu m | HSDB | ||
| Odor Threshold Low: 0.0028 [ppm] | Haz-Map |
Acetaldehyde critical temperature and pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Critical temperature and pressure | 181.5 °C (358.7 °F) | HSDB |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
09 · Fire and explosion
Acetaldehyde 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.
Acetaldehyde fire potential
Highly flammable liquid.
Source: Hazardous Substances Data Bank (HSDB)
Solubility
Acetaldehyde is miscible in all proportions with water and most common organic solvents, eg, acetone, benzene, ethyl alcohol, ethyl ether, gasoline, paraldehyde, toluene, xylenes, turpentine, and acetic acid.
Source: HSDB
10 · Handling and storage
Acetaldehyde storage and handling
Acetaldehyde peroxide formation
B: Compounds that form peroxides on concentration (distillation/evaporation)
Source: Lab and Research Safety, University of Minnesota
Acetaldehyde safe storage
Fireproof. Separated from incompatible materials. See Chemical Dangers. Cooled. Keep in the dark. Store only if stabilized.
Source: ILO-WHO International Chemical Safety Cards (ICSCs)
Acetaldehyde 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. Recommended storage temperature: 2 - 8 °C.
Source: Hazardous Substances Data Bank (HSDB)
Acetaldehyde incompatible materials
Incompatible materials: Oxidizing agents, reducing agents, acids, nitric acid, peroxides, bases, sodium hydroxide, amines, ammonia, oxygen. Warning: Acetaldehyde is oxidized rapidly and exothermically by air, to acetic acid, acid anhydrides, alcohols, halogens, ketones, phenol, hydrogen sulfide gas, hydrogen peroxide.
Source: Hazardous Substances Data Bank (HSDB)
Planning storage for a mix of chemicals? Check Acetaldehyde in the storage compatibility matrix →
11 · Transport
Acetaldehyde 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.
Acetaldehyde under UN 1089 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| ACETALDEHYDE | 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) |
|---|---|---|---|
| Acetaldehyde | 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
Acetaldehyde — frequently asked questions
What is the CAS number of Acetaldehyde?
The CAS number of Acetaldehyde is 75-07-0. Its EC number is 200-836-8.
What is the chemical formula of Acetaldehyde?
The molecular formula of Acetaldehyde is C2H4O and its molecular weight is 44.05 g/mol.
What does a Acetaldehyde label have to show?
Under CLP Annex VI the label for Acetaldehyde carries the pictograms Flame, Health hazard and Exclamation mark and the signal word is Danger.
Is Acetaldehyde flammable?
Yes. CLP Annex VI assigns Acetaldehyde H224 — extremely flammable liquid and vapour. The flash point reported for it is -40 °C (-40 °F) (HSDB).
Is Acetaldehyde a carcinogen?
Yes. CLP Annex VI classifies Acetaldehyde as a category 1A or 1B carcinogen and assigns it H350: may cause cancer. IARC places it in Group 2B: possibly carcinogenic to humans.
What is the exposure limit for Acetaldehyde?
The US occupational exposure limit reported for Acetaldehyde is 200.0 [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 Acetaldehyde?
The boiling point reported for Acetaldehyde is 20.8 °C (69.4 °F) (HSDB).
What is the melting point of Acetaldehyde?
The melting point reported for Acetaldehyde is -123.4 °C (-190.1 °F) (HSDB).
How should Acetaldehyde be stored?
CLP Annex VI assigns Acetaldehyde 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. Recommended storage temperature: 2 - 8 °C. (Hazardous Substances Data Bank (HSDB))
Nearby
Substances next to Acetaldehyde
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