Acetaldehyde

Athanor · official

C₂H₄O · 44.05 g/mol

Also called ethanal, acetic aldehyde

Reagents

Open in Athanor

Drawn from its SMILES with RDKit

DangerExtremely flammable liquid and vapor · Causes serious eye irritation · May cause respiratory irritation · Suspected of causing genetic defects · May cause cancer

Names and identifiers

IUPAC name: acetaldehyde
Synonyms: ethanal, acetic aldehyde, ethyl aldehyde
+ 35 more
Acetylaldehyde, Acetaldehyd, Aldeide acetica, Acetic ethanol, Octowy aldehyd, Aldehyde acetique, RCRA waste number U001, NSC 7594, NCI-C56326, FEMA No. 2003, DTXSID5039224, GO1N1ZPR3B, CHEBI:15343, NSC-7594, DTXCID202, NSC7594, Acetaldehyde Phenolic, Acetaldehyde 1501, RefChem:6606, 200-836-8, ethanone, Ethylaldehyde, Acetaldehyde (natural), ACETYL GROUP, ethaldehyde, Azetaldehyd, CCRIS 1396, HSDB 230, MFCD00006991, UN1089, AI3-31167, CH3CHO, Dexmedetomidine Impurity 9, C2H4O, Acetaldehyd [German]
Molecular formula: C₂H₄O
Empirical formula: C₂H₄O
Molecular weight: 44.05 g/mol
Exact mass: 44.02621
CAS number: 75-07-0
PubChem CID: 177
Canonical SMILES: CC=O
Isomeric SMILES: CC=O
InChI: InChI=1S/C2H4O/c1-2-3/h2H,1H3
InChIKey: IKHGUXGNUITLKF-UHFFFAOYSA-N
Molfile

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

Physical properties

TemperaturePressureDensity

Appearance: Colorless liquid or gas (above 69 degrees F)[6]
6 values
From Hazardous Substances Data Bank (HSDB), the most authoritative source here.
Value As written Source
– Acetaldehyde appears as a clear colorless liquid with a pungent choking odor. Flash point -36 °F. Boiling point 69 °F. Density 6.5 lb / gal. Vapors are heaver than air and irritate the mucous membranes and especially the eyes. Used to make other chemicals. [1] CAMEO Chemicals
– Liquid [2] EPA Chemical Data Reporting (CDR)
– GAS OR COLOURLESS LIQUID WITH PUNGENT ODOUR. [3] ILO-WHO International Chemical Safety Cards (ICSCs)
– Colorless liquid or gas (above 69 °F) with a pungent, fruity odor. [4] Occupational Safety and Health Administration (OSHA)
– Colorless liquid or gas (above 69 °F) with a pungent, fruity odor. [5] The National Institute for Occupational Safety and Health (NIOSH)
–shown Colorless liquid or gas (above 69 degrees F) [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: Pungent, fruity odor[6]
2 values
From Hazardous Substances Data Bank (HSDB), the most authoritative source here.
Value As written Source
–shown Pungent, fruity odor [6] Hazardous Substances Data Bank (HSDB)cites Lewis, R.J. Sr.; Hawley's Condensed Chemical Dictionary 15th Edition. John Wiley & Sons, Inc. New York, NY 2007., p. 5
– Pungent, suffocating odor that is somewhat fruity and quite pleasant in dilute concentrations. [6] Hazardous Substances Data Bank (HSDB)cites Hagemeyer HJ; Acetaldehyde. Kirk-Othmer Encyclopedia of Chemical Technology. (1999-2015). New York, NY: John Wiley & Sons. Online Posting Date: Apr 20, 2014.
Melting point: -123.5 °C[7]
5 values
5 of 5 sources agree on it (most common value).
Value As written Source
−123.5 °C -190.3 °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.
−123 °C -123 °C [3] ILO-WHO International Chemical Safety Cards (ICSCs)
−123 °C -190 °F [4] Occupational Safety and Health Administration (OSHA)
−123.5 °Cshown -123.5 °C [7] PAC Chemical Database, U.S. Department of Energy
−123 °C -190 °F [5] The National Institute for Occupational Safety and Health (NIOSH)
Boiling point: 20.2 °C[3]
5 values
5 of 5 sources agree on it (most common value).
Value As written Source
21 °C 70 °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.
20.2 °Cshown 20.2 °C [3] ILO-WHO International Chemical Safety Cards (ICSCs)
21 °C 69 °F [4] Occupational Safety and Health Administration (OSHA)
20.2 °C 20.2 °C @760 [mm Hg] [7] PAC Chemical Database, U.S. Department of Energy
21 °C 69 °F [5] The National Institute for Occupational Safety and Health (NIOSH)
Density: 0.784 @ 20°C[7]
5 values
5 of 5 sources agree on it (most common value).
Value As written Source
– 0.78 at 68 °F (USCG, 1999) - Less dense 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): 0.78 [3] ILO-WHO International Chemical Safety Cards (ICSCs)
– 0.79 [4] Occupational Safety and Health Administration (OSHA)
–shown 0.784 @ 20°C [7] PAC Chemical Database, U.S. Department of Energy
– 0.79 [5] The National Institute for Occupational Safety and Health (NIOSH)
Solubility in water: Solubility in water: miscible[3]
5 values
From ILO-WHO International Chemical Safety Cards (ICSCs), the most authoritative source here.
Value As written Source
– 0.1 to 1.0 mg/mL at 66 °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.
– Miscible with water /1X10+6 mg/L at 25 °C/ [6] Hazardous Substances Data Bank (HSDB)cites Riddick, J.A., W.B. Bunger, Sakano T.K. Techniques of Chemistry 4th ed., Volume II. Organic Solvents. New York, NY: John Wiley and Sons., 1985., p. 327
– 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. [6] Hazardous Substances Data Bank (HSDB)cites Hagemeyer HJ; Acetaldehyde. Kirk-Othmer Encyclopedia of Chemical Technology. (1999-2015). New York, NY: John Wiley & Sons. Online Posting Date: Apr 20, 2014.
–shown Solubility in water: miscible [3] ILO-WHO International Chemical Safety Cards (ICSCs)
– Miscible [5] The National Institute for Occupational Safety and Health (NIOSH)
log P: 0.63[3]
2 values
Sources disagree; from ILO-WHO International Chemical Safety Cards (ICSCs), the most authoritative.
Value As written Source
– log Kow = -0.34 [6] Hazardous Substances Data Bank (HSDB)cites TSCATS. Toxic Substances Control Act Test Submissions Database. Manufacturer submissions (4, 8d, 8e, FYI) to the USEPA.
–shown 0.63 [3] ILO-WHO International Chemical Safety Cards (ICSCs)
pKa: pKa = 13.57 at 25 °C[6]
Vapor pressure: 758 mmHg at 20 °C[6]
6 values
4 of 4 sources agree on it (most common value).
Value As written Source
400 mmHg 400 mmHg at 40.8 °F [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.
760 mmHg 760 mmHg at 68.4 °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.
902 mmHg 902 mm Hg at 25 °C [6] Hazardous Substances Data Bank (HSDB)cites Boublik, T., Fried, V., and Hala, E., The Vapour Pressures of Pure Substances. Second Revised Edition. Amsterdam: Elsevier, 1984., p. 125
758 mmHgshown 758 mm Hg at 20 °C [6] Hazardous Substances Data Bank (HSDB)cites Boublik, T., Fried, V., and Hala, E., The Vapour Pressures of Pure Substances. Second Revised Edition. Amsterdam: Elsevier, 1984., p. 125
760 mmHg Vapor pressure, kPa at 20 °C: 101 [3] ILO-WHO International Chemical Safety Cards (ICSCs)
740 mmHg 740 [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: -38 °C c.c.[3]
5 values
3 of 5 sources agree on it (most common value).
Value As written Source
−40 °C -40 °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.
−40 °C -40 °C (-40 °F) - closed cup [6] Hazardous Substances Data Bank (HSDB)cites Sigma-Aldrich; Material Safety Data Sheet for Acetaldehyde. Product Number: 00070, Version 3.22 (Revision Date 07/07/2014). Available from, as of January 20, 2015: https://www.sigmaaldrich.com/safety-center.html
−38 °Cshown -38 °C c.c. [3] ILO-WHO International Chemical Safety Cards (ICSCs)
−38 °C -36 °F [4] Occupational Safety and Health Administration (OSHA)
−38 °C -36 °F [5] The National Institute for Occupational Safety and Health (NIOSH)
Autoignition temperature: 185 °C[3]
5 values
2 of 3 sources agree on it (most common value).
Value As written Source
185 °C 365 °F [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.
149 °C 300 °F [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.
175 °C 347 °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.
175 °C 347 °F (175 °C) [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
185 °Cshown 185 °C [3] ILO-WHO International Chemical Safety Cards (ICSCs)
Viscosity: 0.253 mPa s at 9.5 °C[6]
2 values
Only one source reports it.
Value As written Source
–shown 0.253 mPa s at 9.5 °C [6] Hazardous Substances Data Bank (HSDB)cites Eckert M et al; Acetaldehyde. Ullmann's Encyclopedia of Industrial Chemistry. 7th ed. (1999-2015). New York, NY: John Wiley & Sons. Online Posting Date: Dec 15, 2006.
– 0.21 mPa s at 20 °C [6] Hazardous Substances Data Bank (HSDB)cites Eckert M et al; Acetaldehyde. Ullmann's Encyclopedia of Industrial Chemistry. 7th ed. (1999-2015). New York, NY: John Wiley & Sons. Online Posting Date: Dec 15, 2006.

Value	As written	Source
–	Acetaldehyde appears as a clear colorless liquid with a pungent choking odor. Flash point -36 °F. Boiling point 69 °F. Density 6.5 lb / gal. Vapors are heaver than air and irritate the mucous membranes and especially the eyes. Used to make other chemicals.	[1] CAMEO Chemicals
–	Liquid	[2] EPA Chemical Data Reporting (CDR)
–	GAS OR COLOURLESS LIQUID WITH PUNGENT ODOUR.	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–	Colorless liquid or gas (above 69 °F) with a pungent, fruity odor.	[4] Occupational Safety and Health Administration (OSHA)
–	Colorless liquid or gas (above 69 °F) with a pungent, fruity odor.	[5] The National Institute for Occupational Safety and Health (NIOSH)
–shown	Colorless liquid or gas (above 69 degrees F)	[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
–shown	Pungent, fruity odor	[6] Hazardous Substances Data Bank (HSDB)cites Lewis, R.J. Sr.; Hawley's Condensed Chemical Dictionary 15th Edition. John Wiley & Sons, Inc. New York, NY 2007., p. 5
–	Pungent, suffocating odor that is somewhat fruity and quite pleasant in dilute concentrations.	[6] Hazardous Substances Data Bank (HSDB)cites Hagemeyer HJ; Acetaldehyde. Kirk-Othmer Encyclopedia of Chemical Technology. (1999-2015). New York, NY: John Wiley & Sons. Online Posting Date: Apr 20, 2014.

Value	As written	Source
−123.5 °C	-190.3 °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.
−123 °C	-123 °C	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
−123 °C	-190 °F	[4] Occupational Safety and Health Administration (OSHA)
−123.5 °Cshown	-123.5 °C	[7] PAC Chemical Database, U.S. Department of Energy
−123 °C	-190 °F	[5] The National Institute for Occupational Safety and Health (NIOSH)

Value	As written	Source
21 °C	70 °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.
20.2 °Cshown	20.2 °C	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
21 °C	69 °F	[4] Occupational Safety and Health Administration (OSHA)
20.2 °C	20.2 °C @760 [mm Hg]	[7] PAC Chemical Database, U.S. Department of Energy
21 °C	69 °F	[5] The National Institute for Occupational Safety and Health (NIOSH)

Value	As written	Source
–	0.78 at 68 °F (USCG, 1999) - Less dense 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): 0.78	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–	0.79	[4] Occupational Safety and Health Administration (OSHA)
–shown	0.784 @ 20°C	[7] PAC Chemical Database, U.S. Department of Energy
–	0.79	[5] The National Institute for Occupational Safety and Health (NIOSH)

Value	As written	Source
–	0.1 to 1.0 mg/mL at 66 °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.
–	Miscible with water /1X10+6 mg/L at 25 °C/	[6] Hazardous Substances Data Bank (HSDB)cites Riddick, J.A., W.B. Bunger, Sakano T.K. Techniques of Chemistry 4th ed., Volume II. Organic Solvents. New York, NY: John Wiley and Sons., 1985., p. 327
–	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.	[6] Hazardous Substances Data Bank (HSDB)cites Hagemeyer HJ; Acetaldehyde. Kirk-Othmer Encyclopedia of Chemical Technology. (1999-2015). New York, NY: John Wiley & Sons. Online Posting Date: Apr 20, 2014.
–shown	Solubility in water: miscible	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–	Miscible	[5] The National Institute for Occupational Safety and Health (NIOSH)

Value	As written	Source
–	log Kow = -0.34	[6] Hazardous Substances Data Bank (HSDB)cites TSCATS. Toxic Substances Control Act Test Submissions Database. Manufacturer submissions (4, 8d, 8e, FYI) to the USEPA.
–shown	0.63	[3] ILO-WHO International Chemical Safety Cards (ICSCs)

Value	As written	Source
400 mmHg	400 mmHg at 40.8 °F	[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.
760 mmHg	760 mmHg at 68.4 °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.
902 mmHg	902 mm Hg at 25 °C	[6] Hazardous Substances Data Bank (HSDB)cites Boublik, T., Fried, V., and Hala, E., The Vapour Pressures of Pure Substances. Second Revised Edition. Amsterdam: Elsevier, 1984., p. 125
758 mmHgshown	758 mm Hg at 20 °C	[6] Hazardous Substances Data Bank (HSDB)cites Boublik, T., Fried, V., and Hala, E., The Vapour Pressures of Pure Substances. Second Revised Edition. Amsterdam: Elsevier, 1984., p. 125
760 mmHg	Vapor pressure, kPa at 20 °C: 101	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
740 mmHg	740 [mm Hg] @20 °C	[7] PAC Chemical Database, U.S. Department of Energy

Value	As written	Source
−40 °C	-40 °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.
−40 °C	-40 °C (-40 °F) - closed cup	[6] Hazardous Substances Data Bank (HSDB)cites Sigma-Aldrich; Material Safety Data Sheet for Acetaldehyde. Product Number: 00070, Version 3.22 (Revision Date 07/07/2014). Available from, as of January 20, 2015: https://www.sigmaaldrich.com/safety-center.html
−38 °Cshown	-38 °C c.c.	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
−38 °C	-36 °F	[4] Occupational Safety and Health Administration (OSHA)
−38 °C	-36 °F	[5] The National Institute for Occupational Safety and Health (NIOSH)

Value	As written	Source
185 °C	365 °F	[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.
149 °C	300 °F	[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.
175 °C	347 °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.
175 °C	347 °F (175 °C)	[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
185 °Cshown	185 °C	[3] ILO-WHO International Chemical Safety Cards (ICSCs)

Value	As written	Source
–shown	0.253 mPa s at 9.5 °C	[6] Hazardous Substances Data Bank (HSDB)cites Eckert M et al; Acetaldehyde. Ullmann's Encyclopedia of Industrial Chemistry. 7th ed. (1999-2015). New York, NY: John Wiley & Sons. Online Posting Date: Dec 15, 2006.
–	0.21 mPa s at 20 °C	[6] Hazardous Substances Data Bank (HSDB)cites Eckert M et al; Acetaldehyde. Ullmann's Encyclopedia of Industrial Chemistry. 7th ed. (1999-2015). New York, NY: John Wiley & Sons. Online Posting Date: Dec 15, 2006.

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: 3
Rings: 0
Aromatic rings: 0
Fraction sp³ carbons (Fsp3): 0.5
H-bond donors: 0
H-bond acceptors: 1
Rotatable bonds: 0
TPSA (Å²): 17.1
Formal charge: 0
XLogP3: -0.3 PubChem
Complexity: 10 PubChem
Stereocenters: None
Double-bond geometry: None specified
Point group: Cs of one 3D conformer with its hydrogens, by Athanor’s engine (as in the app)

Elemental analysis

C54.53%
H9.15%
O36.32%

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: 0.21 Crippen (Wildman and Crippen 1999)
log S (water solubility): -0.24 ESOL (Delaney 2004), log mol/L
Synthetic accessibility: 3.04 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

Molecular weight ≤ 500: 44.05
log P ≤ 5 (Crippen): 0.21
H-bond donors ≤ 5: 0
H-bond acceptors ≤ 10: 1

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
Harmful or irritant
Health hazard

NFPA 704[6]

H224Extremely flammable liquid and vapor
H319Causes serious eye irritation
H335May cause respiratory irritation
H341Suspected of causing genetic defects
H350May cause cancer

Precautionary statements: 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, P501

View all classifications (3)

[8] Regulation (EC) No 1272/2008 of the European Parliament and of the Council · DangerH224, H319, H335, H341, H350
[9] European Chemicals Agency (ECHA) · 3,049 reports · DangerH224, H302, H311, H317, H319, H335, H341, H350, H351
[6] Hazardous Substances Data Bank (HSDB) · DangerH224, H319, H335, H351, H402

Exposure limits

PEL-TWA (8-Hour Time Weighted Average): 200 ppm (360 mg/m³)[4]
PEL: TWA 200 ppm (360 mg/mÂ³) See Appendix G[5]
REL: Ca See Appendix ASee Appendix C (Aldehydes)[5]
TLV: 25 ppm as STEL; (ceiling value): A3 (confirmed animal carcinogen with unknown relevance to humans).[3]
IDLH: 2000 ppm ; A potential occupational carcinogen. (NIOSH, 2024)[1]
IDLH: NIOSH considers acetaldehyde to be a potential occupational carcinogen.[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 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.[5]
Fresh air, rest. Refer for medical attention.[3]

Storage

Fireproof. Separated from incompatible materials. See Chemical Dangers. Cooled. Keep in the dark. Store only if stabilized.[3]
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.[6]
Store in a cool, dry, well-ventilated location. Inside storage should be in a standard flammable liquids storage warehouse, room, or cabinet. Separate from oxidizing material and other reactive hazards. Store bulk quantities in detached tanks provided with refrigeration and inert gas cover.[6]
It is recommended that steel storage tanks of suitable std be used ... Storage vessels should be fitted with temp gauges & automatic water sprays. ... All tanks & equipment must be earthed. Transfer of material by pipeline must be by pressure of nitrogen. ... Drums containing acetaldehyde should never be stored in direct sunlight or other warm areas.[6]

Incompatibilities

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.[6]
Reacts with oxidizing materials, halogens, amines, strong alkalies, and acids.[6]
Oxygenation of acetaldehyde in presence of cobalt acetate at -20 °C caused precipitation of 1-hydroxyethyl peroxyacetate (acetaldheyde hemi-peracetate), which exploded violently on stirring. Ozone or uv light also catalyzes the autoxidation.[6]
Strong oxidizers, acids, bases, alcohols, ammonia & amines, phenols, ketones, HCN, H2S [Note: Prolonged contact with air may cause formation of peroxides that may explode and burst containers; easily undergoes polymerization].[6]

Safety data sheets on the supplier’s page: Mcule, Angene Chemical, Aladdin Scientific.

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

Spectra

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]Human Metabolome Database (HMDB) · Linked only · via PubChem · retrieved 2026-10-14
[13]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
[14]NIST Mass Spectrometry Data Center · Linked only · via PubChem · retrieved 2026-10-14
[15]MassBank of North America (MoNA) · CC BY 4.0 · 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.