Provenance

Reference data from EU CLP Annex VI and published regulations — verify against your supplier's SDS before use.

Build a label

Substance profile

4-hydroxy-4-methylpentan-2-one

4-hydroxy-4-methylpentan-2-one is a colorless liquid with a faint pleasant odor.

CAS 123-42-2 C6H12O2 116.16 g/mol Warning

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.

CAS number123-42-2
EC number204-626-7
Index number603-016-00-1
Molecular formulaC6H12O2
Molecular weight116.16 g/mol
Chemical class Flammable agents - 2nd degree

Other names for 4-hydroxy-4-methylpentan-2-one

  • diacetone alcohol

02 · GHS classification

Hazards and label elements

Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.

Signal wordWarning
Hazard statements assigned to 4-hydroxy-4-methylpentan-2-one
CodeHazard statement
H319 Causes serious eye irritation.

Precautionary statements: P264, P280, P305, P313, P337, P338

03 · 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.

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
Melting point -44 °C (-47.2 °F) HSDB
-43.89 °C (-47 °F) NIOSH
-42.78 °C (-45 °F) CAMEO
Density 0.94 g/cm³ NIOSH
0.938 g/cm³ at 20 °C CAMEO
0.9306 g/cm³ at 25 °C HSDB
Solubility MISCIBLE WITH WATER, ALCOHOL, ETHER, OTHER SOLVENTS HSDB
Water solubility of 1.0X10+6 mg/l HSDB
Miscible NIOSH
Vapor pressure 1 mmHg NIOSH
3.62 mmHg CAMEO
0.97 mmHg at 20 °C HSDB
Flash point 8 °C (46.4 °F) CLOSED CUP HSDB
51.67 °C (125 °F) NIOSH
Autoignition temperature 603 °C (1117.4 °F) HSDB
603.33 °C (1118 °F) CAMEO
640 °C (1184 °F) ICSC
Lower explosive limit (LEL) 6.9 % by volume HSDB
1.8 % by volume HSDB
Upper explosive limit (UEL) 6.9 % by volume HSDB
Vapor density 4 (air = 1) AIR= 1.00 HSDB
4 (air = 1) ICSC
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
Critical temperature and pressure 333.89 °C (633 °F) HSDB

Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.

04 · Handling and storage

Storing and handling 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)

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 →

Get the free GHS / CLP / OSHA deadline calendar

Verified 2026–2029 compliance dates in one PDF — plus alerts when the rules change.