Substance profile
4-hydroxy-4-methylpentan-2-one
4-hydroxy-4-methylpentan-2-one is a colorless liquid with a faint pleasant odor.
01 · Identification
What 4-hydroxy-4-methylpentan-2-one is
4-hydroxy-4-methylpentan-2-one is a colorless liquid with a faint pleasant odor. Its molecular formula is C6H12O2 and its molecular weight is 116.16 g/mol. It boils at 168 °C, melts at -44 °C, is miscible with water.
Under the GHS it carries the signal word Warning. It is classed as flammable agents - 2nd degree.
02 · Identifiers
4-hydroxy-4-methylpentan-2-one identifiers and molecular data
4-hydroxy-4-methylpentan-2-one CAS number and EC number
4-hydroxy-4-methylpentan-2-one molecular formula and molecular weight
Other names for 4-hydroxy-4-methylpentan-2-one
- diacetone alcohol
03 · GHS classification
4-hydroxy-4-methylpentan-2-one hazard classification
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
4-hydroxy-4-methylpentan-2-one pictograms and signal word
4-hydroxy-4-methylpentan-2-one hazard class and category
| Hazard class | Category | From code | Pictogram |
|---|---|---|---|
| Serious eye damage/eye irritation GHS chapter 3.3 | Category 2A | H319 | GHS07 |
4-hydroxy-4-methylpentan-2-one hazard statements (H-codes)
| Code | Hazard statement |
|---|---|
| H319 | Causes serious eye irritation. |
This page lists only the codes assigned to 4-hydroxy-4-methylpentan-2…. 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 4-hydroxy-4-methylpentan-2…
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 4-hydroxy-4-methylpent… 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
4-hydroxy-4-methylpentan-2-one precautionary statements
CLP Annex VI assigns 6 precautionary statements to 4-hydroxy-4-methylpentan-2…. 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
4-hydroxy-4-methylpentan-2-one 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 | 4-метил-4-хидроксипентан-2-он диацетонов алкохол |
| Spanish español | 4-Hidroxi-4-metilpentan-2-ona alcohol de diacetona |
| Czech čeština | 4-hydroxy-4-methylpentan-2-on diacetonalkohol |
| Danish dansk | 4-hydroxy-4-methyl-2-pentanon diacetonalkohol |
| German Deutsch | 4-Hydroxy-4-methylpentan-2-on Diacetonalkohol |
| Estonian eesti | 4-hüdroksü-4-metüülpentaan-2-oon diatsetoonalkohol |
| Greek ελληνικά | 4-υδροξυ-4-μεθυλοπενταν-2-όνη διακετοναλκοόλη |
| English English | 4-hydroxy-4-methylpentan-2-one diacetone alcohol |
| French français | 4-hydroxy-4-méthylpentan-2-one alcool diacétonique |
| Croatian hrvatski | 4-hidroksi-4-metilpentan-2-on diaceton-alkohol |
| Italian italiano | 4-idrossi-4-metil-pentan-2-one |
| Latvian latviešu | 4-hidroksi-4-metilpentān-2-ons diacetona spirts |
| Lithuanian lietuvių | 4-hidroksi-4-metilpentan-2-onas diacetono alkoholis |
| Hungarian magyar | 4-hidroxi-4-metilpentán-2-on diaceton-alkohol |
| Maltese Malti | 4-idrossi-4-metilpentan-2-on alkoħol tad-diaċetun |
| Dutch Nederlands | 4-hydroxy-4-methylpentaan-2-on diacetonalcohol |
| Polish polski | 4-hydroksy-4-metylopentan-2-on alkohol diacetonowy |
| Portuguese português | 4-hidroxi-4-metil-2-pentanona álcool de diacetona |
| Romanian română | 4-hidroxi-4-metilpentan-2-onă diacetonă alcool |
| Slovak slovenčina | 4-hydroxy-4-metylpentán-2-ón diacetón-alkohol |
| Slovenian slovenščina | 4-hidroksi-4-metilpentan-2-on diaceton alkohol |
| Finnish suomi | 4-hydroksi-4-metyyli-2-pentanoni diasetonialkoholi |
| Swedish svenska | 4-hydroxi-4-metylpentan-2-on diacetonalkohol |
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
4-hydroxy-4-methylpentan-2-one GHS label elements
Everything CLP Annex VI fixes for 4-hydroxy-4-methylpentan-2…, laid out the way it appears on a label. The greyed lines are the parts only the supplier can fill in.
Warning
4-hydroxy-4-methylpentan-2-one
- Causes serious eye irritation.
- Wash … thoroughly after handling.
- Wear protective gloves/protective clothing/eye protection/face protection/hearing protection/…
- IF IN EYES:
- Get medical advice/attention.
- If eye irritation persists:
- Remove contact lenses, if present and easy to do. Continue rinsing.
Supplier name, address and telephone number· Product identifier·Nominal quantity
Need this as an actual label? Open 4-hydroxy-4-methylpentan-2… in the GHS label constructor →
07 · Health hazards
4-hydroxy-4-methylpentan-2-one health hazards and exposure limits
4-hydroxy-4-methylpentan-2-one hazard summary
Narcosis induced in animal inhalation studies; [ACGIH]
Source: Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
4-hydroxy-4-methylpentan-2-one occupational exposure limits
| Limit | Value | Source |
|---|---|---|
| PEL | 50.0 [ppm] | Haz-Map, Information on Hazardous Chemicals and Occupational Diseases |
| PEL | 50 ppm (240 mg/m³) | Occupational Safety and Health Administration (OSHA) |
| PEL | TWA 50 ppm (240 mg/m3) | The National Institute for Occupational Safety and Health (NIOSH) |
| REL | 50 ppm (240 mg/m³) | Occupational Safety and Health Administration (OSHA) |
| REL | TWA 50 ppm (240 mg/m3) | The National Institute for Occupational Safety and Health (NIOSH) |
| IDLH | 1800 ppm ; Based on 10% of the lower explosive limit. (NIOSH, 2024) | CAMEO Chemicals |
| IDLH | 1800.0 [ppm] | Haz-Map, Information on Hazardous Chemicals and Occupational Diseases |
| IDLH | Excerpts from Documentation for IDLHs: It has been reported that eye irritation appeared in volunteers exposed for 15 minutes at 100 ppm [Silverman et al. 1946]. | Haz-Map, Information on Hazardous Chemicals and Occupational Diseases |
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
4-hydroxy-4-methylpentan-2-one 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.
4-hydroxy-4-methylpentan-2-one boiling point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | 167.9 °C (334.2 °F) | at 760 mmHg | HSDB |
| 167.78 °C (334 °F) | NIOSH | ||
| 164.44 °C (328 °F) | at 760 mmHg | CAMEO |
4-hydroxy-4-methylpentan-2-one melting point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Melting point | -44 °C (-47.2 °F) | HSDB | |
| -43.89 °C (-47 °F) | NIOSH | ||
| -42.78 °C (-45 °F) | CAMEO |
4-hydroxy-4-methylpentan-2-one density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Density | 0.94 g/cm³ | NIOSH | |
| 0.938 g/cm³ | at 20 °C | CAMEO | |
| 0.9306 g/cm³ | at 25 °C | HSDB |
4-hydroxy-4-methylpentan-2-one solubility
| Property | Value | Conditions | Source |
|---|---|---|---|
| Solubility | MISCIBLE WITH WATER, ALCOHOL, ETHER, OTHER SOLVENTS | HSDB | |
| Water solubility of 1.0X10+6 mg/l | HSDB | ||
| Miscible | NIOSH |
4-hydroxy-4-methylpentan-2-one vapor pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor pressure | 1 mmHg | NIOSH | |
| 3.62 mmHg | CAMEO | ||
| 0.97 mmHg | at 20 °C | HSDB |
4-hydroxy-4-methylpentan-2-one flash point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Flash point | 8 °C (46.4 °F) | CLOSED CUP | HSDB |
| 51.67 °C (125 °F) | NIOSH |
4-hydroxy-4-methylpentan-2-one autoignition temperature
| Property | Value | Conditions | Source |
|---|---|---|---|
| Autoignition temperature | 603 °C (1117.4 °F) | HSDB | |
| 603.33 °C (1118 °F) | CAMEO | ||
| 640 °C (1184 °F) | ICSC |
4-hydroxy-4-methylpentan-2-one lower explosive limit (LEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Lower explosive limit (LEL) | 6.9 % by volume | HSDB | |
| 1.8 % by volume | HSDB |
4-hydroxy-4-methylpentan-2-one upper explosive limit (UEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Upper explosive limit (UEL) | 6.9 % by volume | HSDB |
4-hydroxy-4-methylpentan-2-one vapor density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor density | 4 (air = 1) | AIR= 1.00 | HSDB |
| 4 (air = 1) | ICSC |
4-hydroxy-4-methylpentan-2-one odor threshold
| Property | Value | Conditions | Source |
|---|---|---|---|
| Odor threshold | Absolute threshold odor concn 0.28 ppm; 100% recognition concn 1.7 ppm | HSDB | |
| Air: 0.28 ul/l; odor safety class B: B= 50-90% of distracted persons perceive warning of TLV. Water: 64 mg/l. | HSDB | ||
| Odor Threshold Low: 0.27 [ppm] | Haz-Map |
4-hydroxy-4-methylpentan-2-one critical temperature and pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Critical temperature and pressure | 333.89 °C (633 °F) | HSDB |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
09 · Fire and explosion
4-hydroxy-4-methylpentan-2… 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.
4-hydroxy-4-methylpentan-2-one fire potential
MODERATE WHEN EXPOSED TO HEAT OR FLAME ...
Source: Hazardous Substances Data Bank (HSDB)
10 · Handling and storage
4-hydroxy-4-methylpentan-2-one storage and handling
4-hydroxy-4-methylpentan-2-one safe storage
Fireproof. Separated from acids, bases, amines and oxidants.
Source: ILO-WHO International Chemical Safety Cards (ICSCs)
4-hydroxy-4-methylpentan-2-one storage conditions
... MATERIALS WHICH ARE TOXIC AS STORED OR WHICH CAN DECOMPOSE INTO TOXIC COMPONENTS ... SHOULD BE STORED IN A COOL WELL-VENTILATED PLACE, OUT OF THE DIRECT RAYS OF THE SUN, AWAY FROM AREAS OF HIGH FIRE HAZARD, AND SHOULD BE PERIODICALLY INSPECTED ... INCOMPATIBLE MATERIALS SHOULD BE ISOLATED ... .
Source: Hazardous Substances Data Bank (HSDB)
4-hydroxy-4-methylpentan-2-one incompatible materials
Strong oxidizers, strong alkalis.
Source: Hazardous Substances Data Bank (HSDB)
Planning storage for a mix of chemicals? Check 4-hydroxy-4-methylpentan… in the storage compatibility matrix →
11 · Transport
4-hydroxy-4-methylpentan-2-one 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.
4-hydroxy-4-methylpentan-2-one under UN 1148 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| DIACETONE ALCOHOL | 3 | F1 | II | |
| DIACETONE ALCOHOL | 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) |
|---|---|---|---|
| Diacetone alcohol | 3 | II | |
| Diacetone alcohol | 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
4-hydroxy-4-methylpentan-2-one — frequently asked questions
What is the CAS number of 4-hydroxy-4-methylpentan-2-one?
The CAS number of 4-hydroxy-4-methylpentan-2-one is 123-42-2. Its EC number is 204-626-7.
What is the chemical formula of 4-hydroxy-4-methylpentan-2-one?
The molecular formula of 4-hydroxy-4-methylpentan-2-one is C6H12O2 and its molecular weight is 116.16 g/mol.
What does a 4-hydroxy-4-methylpentan-2-one label have to show?
Under CLP Annex VI the label for 4-hydroxy-4-methylpentan-2-one carries the pictogram Exclamation mark and the signal word is Warning.
Is 4-hydroxy-4-methylpentan-2-one flammable?
CLP Annex VI assigns 4-hydroxy-4-methylpentan-2-one 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 8 °C (46.4 °F), CLOSED CUP (HSDB).
Is 4-hydroxy-4-methylpentan-2-one a carcinogen?
CLP Annex VI records no harmonised carcinogenicity classification for 4-hydroxy-4-methylpentan-2-one. 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 4-hydroxy-4-methylpentan-2-one?
The US occupational exposure limit reported for 4-hydroxy-4-methylpentan-2-one is 50.0 [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 4-hydroxy-4-methylpentan-2-one?
The boiling point reported for 4-hydroxy-4-methylpentan-2-one is 167.9 °C (334.2 °F), at 760 mmHg (HSDB).
What is the melting point of 4-hydroxy-4-methylpentan-2-one?
The melting point reported for 4-hydroxy-4-methylpentan-2-one is -44 °C (-47.2 °F) (HSDB).
How should 4-hydroxy-4-methylpentan-2-one be stored?
... MATERIALS WHICH ARE TOXIC AS STORED OR WHICH CAN DECOMPOSE INTO TOXIC COMPONENTS ... SHOULD BE STORED IN A COOL WELL-VENTILATED PLACE, OUT OF THE DIRECT RAYS OF THE SUN, AWAY FROM AREAS OF HIGH FIRE HAZARD, AND SHOULD BE PERIODICALLY INSPECTED ... INCOMPATIBLE MATERIALS SHOULD BE ISOLATED ... . (Hazardous Substances Data Bank (HSDB))
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