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CAS 123-42-2

CAS 123-42-2 matches 0 EU annex records across Annex II–VI of Regulation 1223/2009.

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Chemical identity and properties

PubChem 2D chemical structure for CAS 123-42-2
CAS 123-42-2PubChem CID 31256

Diacetone Alcohol

Diacetone alcohol appears as a clear colorless liquid with a pleasant odor. Flash point below 141 °F. Less dense than water. Vapors heavier than air. — CAMEO Chemicals

IUPAC name
4-hydroxy-4-methylpentan-2-one
Molecular formula
C6H12O2
Molecular weight
116.16 g/mol
Exact mass
116.083729621 Da
XLogP3
-0.2
Topological polar surface area
37.3 Ų
Hydrogen-bond donors
1
Hydrogen-bond acceptors
2
Covalent units
1
Defined stereocentres
0

Also known as

4-HYDROXY-4-METHYL-2-PENTANONEDiacetonalkoholDiketone alcoholDiacetonalcoholTyrantonAcetonyldimethylcarbinolPyranton ADiacetone
16 more reported names
PyrantonDiacetone-alcool2-Pentanone, 4-hydroxy-4-methyl-Diacetonalcool2-Methyl-2-pentanol-4-oneDiacetonyl alcohol4-Hydroxy-2-keto-4-methylpentane4-Idrossi-4-metil-pentan-2-oneDimethyl acetonyl carbinol4-Hydroxy-4-methylpentanone-24-Hydroxy-4-methyl-pentan-2-on4-Hydroxy-4-methyl pentan-2-oneQ7WP157PTDNSC-9005CHEBI:55381RefChem:5741
Open full PubChem recordPubChem annotations3D structure image
External database identifiers

Evidence from additional scientific databases

NIH PubChem PUG-View
Exact identifier match31256

Attributed physical-property, hazard, environmental and use annotations.

  • First Aid: Excerpt from NIOSH Pocket Guide for Diacetone alcohol:; Eye: IRRIGATE IMMEDIATELY - If this chemical contacts the eyes, immediately wash (irrigate) the eyes with large amounts of water, occasionally lifting the lower and upper lids. Get medical attention immediately.; Skin: WATER FLUSH PROMPTLY - If this chemical contacts the skin, flush the contaminated skin with water promptly. If this chemical penetrates the clothing, immediately remove the clothing and flush the skin with water promptly. If irritation persists after washing, get medical attention.; Breathing: RESPIRATORY SUPPORT - If a person breathes large amounts of this chemical, move the exposed person to fresh air at once. If breathing has stopped, perform artificial respiration. Keep the affected person warm and at rest. Get medical attention as soon as possible.; Swallow: MEDICAL ATTENTION IMMEDIATELY - If this chemical has been swallowed, get medical attention immediately. (NIOSH, 2024) Source: CAMEO Chemicals
  • ERG2024, Guide 129 (Diacetone alcohol): General First Aid:; · Call 911 or emergency medical service.; · Ensure that medical personnel are aware of the material(s) involved, take precautions to protect themselves and avoid contamination.; · Move victim to fresh air if it can be done safely.; · Administer oxygen if breathing is difficult.; · If victim is not breathing:; -- DO NOT perform mouth-to-mouth resuscitation; the victim may have ingested or inhaled the substance.; -- If equipped and pulse detected, wash face and mouth, then give artificial respiration using a proper respiratory medical device (bag-valve mask, pocket mask equipped with a one-way valve or other device).; -- If no pulse detected or no respiratory medical device available, provide continuous compressions. Conduct a pulse check every two minutes or monitor for any signs of spontaneous respirations.; · Remove and isolate contaminated clothing and shoes.; · For minor skin contact, avoid spreading material on unaffected skin.; · In case of contact with substance, remove immediately by flushing skin or eyes with running water for at least 20 minutes.; · For severe burns, immediate medical attention is required.; · Effects of exposure (inhalation, ingestion, Source: Emergency Response Guidebook (ERG)
  • First Aid: (General first aid procedures); Eye: Irrigate immediately - If this chemical contacts the eyes, immediately wash (irrigate) the eyes with large amounts of water, occasionally lifting the lower and upper lids. Get medical attention immediately.; Skin: Water flush promptly - If this chemical contacts the skin, flush the contaminated skin with water promptly. If this chemical penetrates the clothing, immediately remove the clothing and flush the skin with water promptly. If irritation persists after washing, get medical attention.; Breathing: Respiratory support; Swallow: Medical attention immediately - If this chemical has been swallowed, get medical attention immediately. Source: The National Institute for Occupational Safety and Health (NIOSH)
  • Signal: Warning Source: Regulation (EC) No 1272/2008 of the European Parliament and of the Council
  • GHS Hazard Statements: H319: Causes serious eye irritation [Warning Serious eye damage/eye irritation] Source: Regulation (EC) No 1272/2008 of the European Parliament and of the Council
  • Precautionary Statement Codes: P264+P265, P280, P305+P351+P338, and P337+P317 (click each P-code to see the statement) Source: Regulation (EC) No 1272/2008 of the European Parliament and of the Council
  • Note: This chemical does not meet GHS hazard criteria for < 0.1% (1 of 1556) of reports. Source: European Chemicals Agency (ECHA)
  • Signal: Warning Source: European Chemicals Agency (ECHA)
  • GHS Hazard Statements: H226 (32.3%): Flammable liquid and vapor [Warning Flammable liquids]; H319 (99.9%): Causes serious eye irritation [Warning Serious eye damage/eye irritation]; H335 (31.1%): May cause respiratory irritation [Warning Specific target organ toxicity, single exposure; Respiratory tract irritation]; H361d (16.5%): Suspected of damaging the unborn child [Warning Reproductive toxicity] Source: European Chemicals Agency (ECHA)
  • Precautionary Statement Codes: P203, P210, P233, P240, P241, P242, P243, P261, P264+P265, P271, P280, P303+P361+P353, P304+P340, P305+P351+P338, P318, P319, P337+P317, P370+P378, P403+P233, P403+P235, P405, and P501 (click each P-code to see the statement) Source: European Chemicals Agency (ECHA)
  • ECHA C&L Notifications Summary: Aggregated GHS information provided per 1556 reports by companies from 53 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.; Reported as not meeting GHS hazard criteria per 1 of 1556 reports by companies.; There are 52 notifications provided by 1555 of 1556 reports by companies with hazard statement code(s).; Information may vary between notifications depending on impurities, additives, and other factors. The percentage value in parenthesis indicates the notified classification ratio from companies that provide hazard codes. Only hazard codes with percentage values above 10% are shown. For more detailed information, please visit ECHA C&L website. Source: European Chemicals Agency (ECHA)
  • Signal: Danger Source: NITE-CMC
  • GHS Hazard Statements: H226: Flammable liquid and vapor [Warning Flammable liquids]; H319: Causes serious eye irritation [Warning Serious eye damage/eye irritation]; H335: May cause respiratory irritation [Warning Specific target organ toxicity, single exposure; Respiratory tract irritation]; H336: May cause drowsiness or dizziness [Warning Specific target organ toxicity, single exposure; Narcotic effects]; H360: May damage fertility or the unborn child [Danger Reproductive toxicity]; H371: May cause damage to organs [Warning Specific target organ toxicity, single exposure] Source: NITE-CMC
  • Precautionary Statement Codes: P203, P210, P233, P240, P241, P242, P243, P260, P261, P264, P264+P265, P270, P271, P280, P303+P361+P353, P304+P340, P305+P351+P338, P308+P316, P318, P319, P337+P317, P370+P378, P403+P233, P403+P235, P405, and P501 (click each P-code to see the statement) Source: NITE-CMC
  • Signal: Warning Source: NITE-CMC
  • NFPA Health Rating: 1 - Materials that, under emergency conditions, can cause significant irritation. Source: Hazardous Substances Data Bank (HSDB)
  • NFPA Fire Rating: 2 - Materials that must be moderately heated or exposed to relatively high ambient temperatures before ignition can occur. Materials would not under normal conditions form hazardous atmospheres with air, but under high ambient temperatures or under moderate heating could release vapor in sufficient quantities to produce hazardous atmospheres with air. Source: Hazardous Substances Data Bank (HSDB)
  • NFPA Instability Rating: 0 - Materials that in themselves are normally stable, even under fire conditions. Source: Hazardous Substances Data Bank (HSDB)
  • Cosmetic Ingredient Review Finding(s): Safe in the present practices of use and concentration. Ingredient, concentration, and use information are available in documents discoverable at https://cir-reports.cir-safety.org Source: Cosmetic Ingredient Review (CIR)
  • Environmental Bioconcentration: An estimated BCF of 0.50 can be calculated(SRC) from an estimated log Kow of -0.098(2) using a recommended regression equation(1). Based upon the estimated BCF and the reported infinite solubility of the compound in water(3), 4-hydroxy-4-methyl-2-pentanone will not be expected to significantly bioconcentrate in aquatic organisms(SRC). Source: Hazardous Substances Data Bank (HSDB)
  • Environmental Fate: TERRESTRIAL FATE: If 4-hydroxy-4-methyl-2-pentanone is released to soil, it will be expected to exhibit very high mobility(1), based upon the reported infinite solubility of the compound in water(2) and an estimated Koc of 21 calculated(3,SRC) from a measured log Kow(4). The compound may, therefore, leach through soil to groundwater if it does not biodegrade first(SRC). It may be subject to biodegradation in soil based upon results observed in laboratory biodegradation aqueous aerobic screening tests using acclimated mixed microbial cultures as inoculums(5,6) provided suitably acclimated microbial populations are present(7,SRC). It should not be subject to volatilization from moist near surface soil based upon(3,SRC) an estimated Henry's Law constant of 4.24X10-9 atm-cu m/mole(9,SRC). However, it may volatilize from dry near-surface soil and other dry surfaces based upon its vapor pressure of 1.71 mm Hg at 25 °C(8). Source: Hazardous Substances Data Bank (HSDB)
  • Environmental Fate: AQUATIC FATE: If 4-hydroxy-4-methyl-2-pentanone is released to water, it will not be expected to adsorb to sediment or suspended particulate matter or to bioconcentrate in aquatic organisms based upon its estimated Koc and BCF, respectively, calculated(1,SRC) from the measured log Kow(2), and its high solubility in water(3). Although no data were found regarding biodegradation in environmental media, the compound may be subject to biodegradation in natural waters based upon results observed in laboratory aqueous aerobic biodegradation screening tests using acclimated mixed microbial cultures as inoculums(4,5) provided suitably acclimated microbial populations are present(6,SRC). It should not be subject to volatilization from surface waters based upon(1,SRC) an estimated Henry's Law constant of 4.24X10-9 atm-cu m/mole(7,SRC) Hydrolysis should not be an important removal process since aliphatic alcohols and ketones (the two functional groups that 4-hydroxy-4-methyl-2-pentanone contains) generally are resistant to hydrolysis(1). Source: Hazardous Substances Data Bank (HSDB)
  • Environmental Fate: ATMOSPHERIC FATE: If 4-hydroxy-4-methyl-2-pentanone is released to the atmosphere, it can be expected to exist mainly in the vapor-phase in the ambient atmosphere(1,SRC) based upon an experimental vapor pressure of 1.71 mm Hg at 25 °C(2). The estimated rate constant for vapor-phase reaction with photochemically produced hydroxyl radicals is 1.34X10-12 cu cm/molecule-sec at 25 °C(3) which corresponds to an atmospheric half-life of 12 days at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(SRC). 4-Hydroxy-4-methyl-2-pentanone may be susceptible to direct photolysis in the atmosphere(SRC) based upon its possible absorption(SRC) of light at wavelengths >290 nm(4). Based upon its high water solubility(5), the compound may be susceptible to removal from the atmosphere by washout(SRC). Source: Hazardous Substances Data Bank (HSDB)

Mapped by: Existing checksum-valid CAS to unique PubChem CID match. Retrieved: 2026-08-31. Open source record

Scientific classifications and hazard annotations provide context and do not replace the market-specific regulatory decision shown above.

Additional source coverage and match status
SourceResultChecked
NIH PubChem PUG-ViewExact match2026-08-31

A recorded no-match is useful evidence that the source was checked; it is not a claim that the substance does not exist elsewhere.

Retrieved from NIH PubChem on 2026-08-31 by checksum-valid CAS matching. Chemical properties do not replace the regulatory decision on this page.

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How CAS 123-42-2 is used on this site

CAS 123-42-2 is the Chemical Abstracts Service identifier used to pin this page to a specific substance. In the current dataset, 0 EU annex records share this identifier, which helps you cross-check whether the same substance appears under one regulatory context or several.

Use this page when a supplier specification, SDS or raw-material dossier gives you CAS 123-42-2 and you need to see every linked Annex II–VI record in one place. The entry cards above are the quickest route to concentration limits, warnings, annex placement and product-type conditions.