Acetic anhydride

Athanor · official

C₄H₆O₃ · 102.09 g/mol

IUPAC name: acetyl acetate

Also called Ac2O, ethanoic anhydride

Reagents

Open in Athanor

Drawn from its SMILES with RDKit

DangerFlammable liquid and vapor · Harmful if swallowed · Causes severe skin burns and eye damage · Harmful if inhaled

Names and identifiers

IUPAC name: acetyl acetate
Synonyms: Ac2O, ethanoic anhydride, Acetyl acetate
+ 35 more
Acetanhydride, Ethanoic anhydride, Acetyl oxide, Acetyl anhydride, Acetic oxide, Acetic acid, anhydride, acetic acid anhydride, Acetyl ether, Anhydride acetique, Anidride acetica, Octowy bezwodnik, Azijnzuuranhydride, Essigsaeureanhydrid, Ethanoic anhydrate, Anhydrid kyseliny octove, Acetic acid, 1,1'-anhydride, DTXSID0024395, 2E48G1QI9Q, DTXCID704395, CHEBI:36610, RefChem:6607, 203-564-8, ethanoyl ethanoate, (CH3CO)2O, Acetic anhydride-1,1'-13C2,d6, MFCD00008705, Acetic anhydride-1,1-13C2, Caswell No. 003A, HSDB 233, Octowy bezwodnik [Polish], Azijnzuuranhydride [Dutch], Anidride acetica [Italian], Anhydride acetique [French], Essigsaeureanhydrid [German], CCRIS 688
Molecular formula: C₄H₆O₃
Empirical formula: C₄H₆O₃
Molecular weight: 102.09 g/mol
Exact mass: 102.03169
CAS number: 108-24-7
PubChem CID: 7918
Canonical SMILES: CC(=O)OC(=O)C
Isomeric SMILES: CC(=O)OC(=O)C
InChI: InChI=1S/C4H6O3/c1-3(5)7-4(2)6/h1-2H3
InChIKey: WFDIJRYMOXRFFG-UHFFFAOYSA-N
Molfile

Names, InChI and the identifiers from PubChem, retrieved 2026-10-14.

Physical properties

TemperaturePressureDensity

Appearance: Colorless liquid[6]
6 values
From Hazardous Substances Data Bank (HSDB), the most authoritative source here.
Value As written Source
– Acetic anhydride appears as a clear colorless liquid with a strong odor of vinegar. Flash point 129 °F. Corrosive to metals and tissue. Density 9.0 lb /gal. Used to make fibers, plastics, pharmaceuticals, dyes, and explosives. [1] CAMEO Chemicals
– Liquid [2] EPA Chemical Data Reporting (CDR)
– COLOURLESS LIQUID WITH PUNGENT ODOUR. [3] ILO-WHO International Chemical Safety Cards (ICSCs)
– Colorless liquid with a strong, pungent, vinegar-like odor. [4] Occupational Safety and Health Administration (OSHA)
– Colorless liquid with a strong, pungent, vinegar-like odor. [5] The National Institute for Occupational Safety and Health (NIOSH)
–shown Colorless liquid [6] Hazardous Substances Data Bank (HSDB)cites NIOSH. NIOSH Pocket Guide to Chemical Hazards. Department of Health & Human Services, Centers for Disease Control & Prevention. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2010-168 (2010). Available from: https://www.cdc.gov/niosh/npg
Odor: Strong, pungent, vinegar-like odor[6]
Melting point: -73.1 °C[7]
5 values
5 of 5 sources agree on it (most common value).
Value As written Source
−73.1 °C -99.6 °F (NTP, 1992) [1] CAMEO Chemicalscites National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.
−73 °C -73 °C [3] ILO-WHO International Chemical Safety Cards (ICSCs)
−73 °C -99 °F [4] Occupational Safety and Health Administration (OSHA)
−73.1 °Cshown -73.1 °C [7] PAC Chemical Database, U.S. Department of Energy
−73 °C -99 °F [5] The National Institute for Occupational Safety and Health (NIOSH)
Boiling point: 139.55 °C (283.19 °F) at 760 mmHg (NTP, 1992)[1]
5 values
5 of 5 sources agree on it (most common value).
Value As written Source
139.6 °Cshown 283.19 °F at 760 mmHg (NTP, 1992) [1] CAMEO Chemicalscites National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.
139 °C 139 °C [3] ILO-WHO International Chemical Safety Cards (ICSCs)
139 °C 282 °F [4] Occupational Safety and Health Administration (OSHA)
139.8 °C 139.8 °C @760 [mm Hg] [7] PAC Chemical Database, U.S. Department of Energy
139 °C 282 °F [5] The National Institute for Occupational Safety and Health (NIOSH)
Density: 1.082 @ 20°C[7]
5 values
5 of 5 sources agree on it (most common value).
Value As written Source
– 1.08 (USCG, 1999) - Denser than water [1] CAMEO Chemicalscites U.S. Coast Guard. 1999. Chemical Hazard Response Information System (CHRIS) - Hazardous Chemical Data. Commandant Instruction 16465.12C. Washington, D.C.: U.S. Government Printing Office.
– Relative density (water = 1): 1.08 (20 °C) [3] ILO-WHO International Chemical Safety Cards (ICSCs)
– 1.08 [4] Occupational Safety and Health Administration (OSHA)
–shown 1.082 @ 20°C [7] PAC Chemical Database, U.S. Department of Energy
– 1.08 [5] The National Institute for Occupational Safety and Health (NIOSH)
Solubility in water: Solubility in water: reaction, releasing heat[3]
5 values
From ILO-WHO International Chemical Safety Cards (ICSCs), the most authoritative source here.
Value As written Source
– Soluble in cold (greater than or equal to 10mg/ml); Decomposes in hot (NTP, 1992) [1] CAMEO Chemicalscites National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.
– In water, 120 g/L at 20 °C [6] Hazardous Substances Data Bank (HSDB)cites Yalkowsky, S.H., He, Yan, Jain, P. Handbook of Aqueous Solubility Data Second Edition. CRC Press, Boca Raton, FL 2010, p. 96
– Miscible with ethanol, ether, acetic acid, and ethyl acetate [6] Hazardous Substances Data Bank (HSDB)cites ITII. Toxic and Hazarous Industrial Chemicals Safety Manual. Tokyo, Japan: The International Technical Information Institute, 1982., p. 3
–shown Solubility in water: reaction, releasing heat [3] ILO-WHO International Chemical Safety Cards (ICSCs)
– 12% [5] The National Institute for Occupational Safety and Health (NIOSH)
log P: -0.27 (calculated)[3]
Vapor pressure: Vapor pressure, kPa at 20 °C: 0.5[3]
3 values
Sources disagree; from ILO-WHO International Chemical Safety Cards (ICSCs), the most authoritative.
Value As written Source
10 mmHg 10 mmHg at 96.8 °F (NTP, 1992) [1] CAMEO Chemicalscites National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.
3.8 mmHgshown Vapor pressure, kPa at 20 °C: 0.5 [3] ILO-WHO International Chemical Safety Cards (ICSCs)
4.7 mmHg 4.7 [mm Hg] @20 °C [7] PAC Chemical Database, U.S. Department of Energy
2 more values were reported but failed the checks (unreadable or out of range), so they are not shown.
Flash point: 49 °C (120 °F) Closed cup[6]
5 values
5 of 5 sources agree on it (most common value).
Value As written Source
49 °C 121 °F (NTP, 1992) [1] CAMEO Chemicalscites National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.
49 °Cshown 120 °F (49 °C) Closed cup [6] Hazardous Substances Data Bank (HSDB)cites National Fire Protection Association; Fire Protection Guide to Hazardous Materials. 14TH Edition, Quincy, MA 2010, p. 325-9
49 °C 49 °C c.c. [3] ILO-WHO International Chemical Safety Cards (ICSCs)
49 °C 120 °F [4] Occupational Safety and Health Administration (OSHA)
49 °C 120 °F [5] The National Institute for Occupational Safety and Health (NIOSH)
Autoignition temperature: 316 °C[3]
3 values
2 of 3 sources agree on it (most common value).
Value As written Source
330 °C 626 °F (USCG, 1999) [1] CAMEO Chemicalscites U.S. Coast Guard. 1999. Chemical Hazard Response Information System (CHRIS) - Hazardous Chemical Data. Commandant Instruction 16465.12C. Washington, D.C.: U.S. Government Printing Office.
316 °C 316 °C (600 °F) [6] Hazardous Substances Data Bank (HSDB)cites National Fire Protection Association; Fire Protection Guide to Hazardous Materials. 14TH Edition, Quincy, MA 2010, p. 325-9
316 °Cshown 316 °C [3] ILO-WHO International Chemical Safety Cards (ICSCs)

Value	As written	Source
–	Acetic anhydride appears as a clear colorless liquid with a strong odor of vinegar. Flash point 129 °F. Corrosive to metals and tissue. Density 9.0 lb /gal. Used to make fibers, plastics, pharmaceuticals, dyes, and explosives.	[1] CAMEO Chemicals
–	Liquid	[2] EPA Chemical Data Reporting (CDR)
–	COLOURLESS LIQUID WITH PUNGENT ODOUR.	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–	Colorless liquid with a strong, pungent, vinegar-like odor.	[4] Occupational Safety and Health Administration (OSHA)
–	Colorless liquid with a strong, pungent, vinegar-like odor.	[5] The National Institute for Occupational Safety and Health (NIOSH)
–shown	Colorless liquid	[6] Hazardous Substances Data Bank (HSDB)cites NIOSH. NIOSH Pocket Guide to Chemical Hazards. Department of Health & Human Services, Centers for Disease Control & Prevention. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2010-168 (2010). Available from: https://www.cdc.gov/niosh/npg

Value	As written	Source
−73.1 °C	-99.6 °F (NTP, 1992)	[1] CAMEO Chemicalscites National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.
−73 °C	-73 °C	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
−73 °C	-99 °F	[4] Occupational Safety and Health Administration (OSHA)
−73.1 °Cshown	-73.1 °C	[7] PAC Chemical Database, U.S. Department of Energy
−73 °C	-99 °F	[5] The National Institute for Occupational Safety and Health (NIOSH)

Value	As written	Source
139.6 °Cshown	283.19 °F at 760 mmHg (NTP, 1992)	[1] CAMEO Chemicalscites National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.
139 °C	139 °C	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
139 °C	282 °F	[4] Occupational Safety and Health Administration (OSHA)
139.8 °C	139.8 °C @760 [mm Hg]	[7] PAC Chemical Database, U.S. Department of Energy
139 °C	282 °F	[5] The National Institute for Occupational Safety and Health (NIOSH)

Value	As written	Source
–	1.08 (USCG, 1999) - Denser than water	[1] CAMEO Chemicalscites U.S. Coast Guard. 1999. Chemical Hazard Response Information System (CHRIS) - Hazardous Chemical Data. Commandant Instruction 16465.12C. Washington, D.C.: U.S. Government Printing Office.
–	Relative density (water = 1): 1.08 (20 °C)	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–	1.08	[4] Occupational Safety and Health Administration (OSHA)
–shown	1.082 @ 20°C	[7] PAC Chemical Database, U.S. Department of Energy
–	1.08	[5] The National Institute for Occupational Safety and Health (NIOSH)

Value	As written	Source
–	Soluble in cold (greater than or equal to 10mg/ml); Decomposes in hot (NTP, 1992)	[1] CAMEO Chemicalscites National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.
–	In water, 120 g/L at 20 °C	[6] Hazardous Substances Data Bank (HSDB)cites Yalkowsky, S.H., He, Yan, Jain, P. Handbook of Aqueous Solubility Data Second Edition. CRC Press, Boca Raton, FL 2010, p. 96
–	Miscible with ethanol, ether, acetic acid, and ethyl acetate	[6] Hazardous Substances Data Bank (HSDB)cites ITII. Toxic and Hazarous Industrial Chemicals Safety Manual. Tokyo, Japan: The International Technical Information Institute, 1982., p. 3
–shown	Solubility in water: reaction, releasing heat	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–	12%	[5] The National Institute for Occupational Safety and Health (NIOSH)

Value	As written	Source
10 mmHg	10 mmHg at 96.8 °F (NTP, 1992)	[1] CAMEO Chemicalscites National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.
3.8 mmHgshown	Vapor pressure, kPa at 20 °C: 0.5	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
4.7 mmHg	4.7 [mm Hg] @20 °C	[7] PAC Chemical Database, U.S. Department of Energy

Value	As written	Source
49 °C	121 °F (NTP, 1992)	[1] CAMEO Chemicalscites National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.
49 °Cshown	120 °F (49 °C) Closed cup	[6] Hazardous Substances Data Bank (HSDB)cites National Fire Protection Association; Fire Protection Guide to Hazardous Materials. 14TH Edition, Quincy, MA 2010, p. 325-9
49 °C	49 °C c.c.	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
49 °C	120 °F	[4] Occupational Safety and Health Administration (OSHA)
49 °C	120 °F	[5] The National Institute for Occupational Safety and Health (NIOSH)

Value	As written	Source
330 °C	626 °F (USCG, 1999)	[1] CAMEO Chemicalscites U.S. Coast Guard. 1999. Chemical Hazard Response Information System (CHRIS) - Hazardous Chemical Data. Commandant Instruction 16465.12C. Washington, D.C.: U.S. Government Printing Office.
316 °C	316 °C (600 °F)	[6] Hazardous Substances Data Bank (HSDB)cites National Fire Protection Association; Fire Protection Guide to Hazardous Materials. 14TH Edition, Quincy, MA 2010, p. 325-9
316 °Cshown	316 °C	[3] ILO-WHO International Chemical Safety Cards (ICSCs)

Each value as its source reports it, with the source's number after it (listed under References). Where several sources report a property, the row shows the value most of them agree on, the rule the app uses; open the values to see every one.

Calculated

Heavy atoms: 7
Rings: 0
Aromatic rings: 0
Fraction sp³ carbons (Fsp3): 0.5
H-bond donors: 0
H-bond acceptors: 3
Rotatable bonds: 0 computed here · PubChem 2
TPSA (Å²): 43.4
Formal charge: 0
XLogP3: -0.1 PubChem
Complexity: 83 PubChem
Stereocenters: None
Double-bond geometry: None specified
Point group: C2v of one 3D conformer with its hydrogens, by Athanor’s engine (as in the app)

Elemental analysis

C47.06%
H5.92%
O47.01%

Isotope pattern

Each peak is a nominal mass with its abundance-weighted exact mass, as a percentage of the tallest, from IUPAC natural isotope abundances.

Computed from the structure with RDKit 2026.09 when this page was built, beside PubChem's own computed values from its record; where the two differ, both are shown.

Predicted

log P: 0.1 Crippen (Wildman and Crippen 1999)
log S (water solubility): -0.53 ESOL (Delaney 2004), log mol/L
Synthetic accessibility: 2.32 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

Molecular weight ≤ 500: 102.09
log P ≤ 5 (Crippen): 0.1
H-bond donors ≤ 5: 0
H-bond acceptors ≤ 10: 3

Passes all four rules.

¹³C NMR shifts, predicted

Predictions, not measurements; each names its method. A measured log P, where a source reports one, is under Physical properties.

Safety

Danger

Harmonized EU classification (CLP Annex VI). Source [8].

Flammable
Corrosive
Harmful or irritant

NFPA 704[6]

H226Flammable liquid and vapor
H302Harmful if swallowed
H314Causes severe skin burns and eye damage
H332Harmful if inhaled

Precautionary statements: P210, P233, P240, P241, P242, P243, P260, P261, P264, P270, P271, P280, P301+P317, P301+P330+P331, P302+P361+P354, P303+P361+P353, P304+P340, P305+P354+P338, P316, P317, P321, P330, P363, P370+P378, P403+P235, P405, P501

View all classifications (4)

[8] Regulation (EC) No 1272/2008 of the European Parliament and of the Council · DangerH226, H302, H314, H332
[9] European Chemicals Agency (ECHA) · 1,712 reports · DangerH226, H302, H314, H318, H330, H331, H332, H335
[9] European Chemicals Agency (ECHA) · 39 reports · DangerH226, H302, H314, H332
[6] Hazardous Substances Data Bank (HSDB) · DangerH226, H302, H314, H318, H330

Exposure limits

PEL-TWA (8-Hour Time Weighted Average): 5 ppm (20 mg/m³)[4]
PEL: TWA 5 ppm (20 mg/m3) See Appendix G[5]
REL: C 5 ppm (20 mg/m3)[5]
TLV: 1 ppm as TWA; 3 ppm as STEL; A4 (not classifiable as a human carcinogen)[3]
IDLH: 200 ppm (NIOSH, 2024)[1]
IDLH: 200 ppm[6]

First aid

Eyes: First check the victim for contact lenses and remove if present. Flush victim's eyes with water or normal saline solution for 20 to 30 minutes while simultaneously calling a hospital or poison control center. Do not put any ointments, oils, or medication in the victim's eyes without specific instructions from a physician. Immediately transport the victim after flushing eyes to a hospital even if no symptoms (such as redness or irritation) develop. Skin: Immediately flood affected skin with water while removing and isolating all contaminated clothing.[1]
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…[10]
(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 immediately - If this chemical contacts the skin, immediately flush the contaminated skin with water. If this chemical penetrates the clothing, immediately remove the clothing and flush the skin with water.[5]
Fresh air, rest. Half-upright position. Artificial respiration may be needed. Refer immediately for medical attention.[3]

Storage

Store only in original container. Separated from food and feedstuffs and incompatible materials. See Chemical Dangers. Fireproof. Dry.[3]
Store in cool, dry, well-ventilated location. Outside or detached storage is preferred. Store away from heat, oxidizers, and sunlight. Exclude moisture from vapor space in storage tanks.[6]
Store away from ... Foods, nitric acid, sodium peroxide.[6]
Keep away from moisture and all alkalies.[6]

Incompatibilities

A violent reaction (acetic anhydride and glycerol) occurs between these reactants in the presence of phosphorus oxychloride as a catalyst.[6]
...can react vigorously with oxidizing materials, will react violently on contact with water or steam.[6]
Use of mixtures of metal nitrates with acetic anhydride as a nitrating agent may be hazardous, depending on the proportions of reactants and on the cation; copper nitrate or sodium nitrate usually cause a violent reactions.[6]
Mixing acetic anhydride with chromic acid caused a violent reaction with the release of heat.[6]

Safety data sheets on the supplier’s page: Oakwood Products, AA BLOCKS, Sigma-Aldrich.

Always read the supplier’s safety data sheet before working with it.

Spectra

NMRHazardous Substances Data Bank (HSDB) · NMRShiftDB
1H NMRSpectraBase (BRUKER AC-300)
13C NMRSpectraBase
17O NMRSpectraBase
GC-MSNIST Mass Spectrometry Data Center · NIST Mass Spectrometry Data Center · NIST Mass Spectrometry Data Center · SpectraBase (GC/MS)
Other MSHazardous Substances Data Bank (HSDB)
UVHazardous Substances Data Bank (HSDB)
IRHazardous Substances Data Bank (HSDB)
FTIRSpectraBase (Bio-Rad FTS · Neat (KBr))
ATR-IRSpectraBase (Bio-Rad FTS · ATR-Neat (DuraSamplIR II))
Near IRSpectraBase (BRUKER IFS 88 · NIR)
Vapor Phase IRSpectraBase (Bruker IFS 85 · Gas-GC)
RamanHazardous Substances Data Bank (HSDB) · SpectraBase

Experimental spectra held by these sources; each link opens the source's own record.

Literature

Reading PubChem, OpenAlex and GSRS…

Bioactivity

Reading ChEMBL…

References

[1]CAMEO Chemicals · Public domain (NOAA) · via PubChem · retrieved 2026-10-14
[2]EPA Chemical Data Reporting (CDR) · Public domain (US EPA) · via PubChem · retrieved 2026-10-14
[3]ILO-WHO International Chemical Safety Cards (ICSCs) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
[4]Occupational Safety and Health Administration (OSHA) · Public domain (US DOL) · via PubChem · retrieved 2026-10-14
[5]The National Institute for Occupational Safety and Health (NIOSH) · Public domain (US CDC) · via PubChem · retrieved 2026-10-14
[6]Hazardous Substances Data Bank (HSDB) · Public domain (US NLM) · via PubChem · retrieved 2026-10-14
[7]PAC Chemical Database, U.S. Department of Energy · Public domain (US DOE) · via PubChem · retrieved 2026-10-14
[8]Regulation (EC) No 1272/2008 of the European Parliament and of the Council · EU reuse policy, CC BY 4.0 · via PubChem · retrieved 2026-10-14
[9]European Chemicals Agency (ECHA) · ECHA legal notice: reuse with acknowledgement · via PubChem · retrieved 2026-10-14
[10]Emergency Response Guidebook (ERG) · Public domain (US DOT) · via PubChem · retrieved 2026-10-14
[11]NMRShiftDB · Linked only · via PubChem · retrieved 2026-10-14
[12]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
[13]NIST Mass Spectrometry Data Center · Linked only · via PubChem · retrieved 2026-10-14
·Calculated values: computed by Athanor with RDKit 2026.09 from the structure.
·Literature on PubChem

Data last updated 2026-10-14.