Propionic acid
Athanor · official
C3H6O2 · 74.08 g/mol
IUPAC name: propanoic acid
Also called propanoic acid, E280
DangerCauses severe skin burns and eye damageNames and identifiers
- IUPAC name
- propanoic acid
- Synonyms
- propanoic acid, E280, Propanoic acid
+ 37 more
methylacetic acid, ethylformic acid, Carboxyethane, Metacetonic acid, Luprosil, Ethanecarboxylic acid, Pseudoacetic acid, Monoprop, Prozoin, Antischim B, Propionoic acid, Methyl acetic acid, Acide propionique, Sentry grain preserver, Propcorn, Propkorn, C3 acid, Tenox P grain preservative, Caswell No. 707, Adofeed, Propionic acid grain preserver, FEMA No. 2924, Kyselina propionova, FEMA Number 2924, DTXSID8025961, JHU490RVYR, INS NO.280, CHEBI:30768, INS-280, DTXCID505961, E-280, RefChem:6676, 201-176-3, Propionic acid (natural), Acide propionique [French], Kyselina propionova [Czech], Propionsaeure
- Molecular formula
- C3H6O2
- Empirical formula
- C3H6O2
- Molecular weight
- 74.08 g/mol
- Exact mass
- 74.03678
- CAS number
- 79-09-4
- PubChem CID
- 1032
- Canonical SMILES
- CCC(=O)O
- Isomeric SMILES
- CCC(=O)O
- InChI
- InChI=1S/C3H6O2/c1-2-3(4)5/h2H2,1H3,(H,4,5)
- InChIKey
- XBDQKXXYIPTUBI-UHFFFAOYSA-N
- Molfile
Names, InChI and the identifiers from PubChem, retrieved 2026-10-14.
Physical properties
TemperaturePressureDensity
- Appearance
- Clear, colorless liquid[6]
8 values
From Hazardous Substances Data Bank (HSDB), the most authoritative source here.
Value As written Source – Propionic acid is a colorless liquid with a sharp rancid odor. Produces irritating vapor. (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. – Propionic acid, [solution] appears as a clear oily aqueous liquid with a pungent rancid odor. Burns skin and the vapors irritate mucous membranes. Corrosive to most metals and tissue. [1] CAMEO Chemicals – Liquid [2] EPA Chemical Data Reporting (CDR) – OILY COLOURLESS LIQUID WITH PUNGENT ODOUR. [3] ILO-WHO International Chemical Safety Cards (ICSCs) – Colorless, oily liquid with a pungent, disagreeable, rancid odor. [4] Occupational Safety and Health Administration (OSHA) – Colorless, oily liquid with a pungent, disagreeable, rancid odor. [Note: A solid below 5 °F.] [5] The National Institute for Occupational Safety and Health (NIOSH) – Colorless, oily liquid [Note: A solid below 5 degrees F] [6] Hazardous Substances Data Bank (HSDB)cites NIOSH. NIOSH Pocket Guide to Chemical Hazards & Other Databases CD-ROM. Department of Health & Human Services, Centers for Disease Prevention & Control. National Institute for Occupational Safety & Health. DHHS (NIOSH) Publication No. 2005-151 (2005) –shown Clear, colorless liquid [6] Hazardous Substances Data Bank (HSDB)cites Gerhartz, W. (exec ed.). Ullmann's Encyclopedia of Industrial Chemistry. 5th ed.Vol A1: Deerfield Beach, FL: VCH Publishers, 1985 to Present., p. VA22: 224 (1993) - Melting point
- -21.5 °C[7]
5 values
4 of 5 sources agree on it (most common value).
Value As written Source −21.5 °C -6.7 °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. −21 °C -21 °C [3] ILO-WHO International Chemical Safety Cards (ICSCs) −21.5 °C -6.7 °F [4] Occupational Safety and Health Administration (OSHA) −21.5 °Cshown -21.5 °C [7] PAC Chemical Database, U.S. Department of Energy −15 °C 5 °F [5] The National Institute for Occupational Safety and Health (NIOSH) - Boiling point
- 141.1 °C @760 [mmHg][7]
5 values
5 of 5 sources agree on it (most common value).
Value As written Source 140.7 °C 285.3 °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. 141 °C 141 °C [3] ILO-WHO International Chemical Safety Cards (ICSCs) 141 °C 286 °F [4] Occupational Safety and Health Administration (OSHA) 141.1 °Cshown 141.1 °C @760 [mm Hg] [7] PAC Chemical Database, U.S. Department of Energy 141 °C 286 °F [5] The National Institute for Occupational Safety and Health (NIOSH) - Density
- 0.99815 @25 °C[7]
5 values
5 of 5 sources agree on it (most common value).
Value As written Source – 0.995 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): 0.99 [3] ILO-WHO International Chemical Safety Cards (ICSCs) – 0.99 [4] Occupational Safety and Health Administration (OSHA) –shown 0.99815 @25 °C [7] PAC Chemical Database, U.S. Department of Energy – 0.99 [5] The National Institute for Occupational Safety and Health (NIOSH) 2 more values were reported but failed the checks (unreadable or out of range), so they are not shown.
- Solubility in water
- Solubility in water: very soluble[3]
5 values
From ILO-WHO International Chemical Safety Cards (ICSCs), the most authoritative source here.
Value As written Source – greater than or equal to 100 mg/mL at 72 °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. – For more Solubility (Complete) data for PROPIONIC ACID (6 total), please visit the HSDB record page. [6] Hazardous Substances Data Bank (HSDB) – In water, 1.0X10+6 mg/L at 25 °C /miscible/ [6] Hazardous Substances Data Bank (HSDB)cites US EPA; Treatability manual I. Treatability data; EPA-600/2-82-001a. Washington, DC: US EPA (1981) –shown Solubility in water: very soluble [3] ILO-WHO International Chemical Safety Cards (ICSCs) – Miscible [5] The National Institute for Occupational Safety and Health (NIOSH) - log P
- 0.33[3]
2 values
2 of 2 sources agree on it (most common value).
Value As written Source – log Kow = 0.33 [6] Hazardous Substances Data Bank (HSDB)cites Hansch, C., Leo, A., D. Hoekman. Exploring QSAR - Hydrophobic, Electronic, and Steric Constants. Washington, DC: American Chemical Society., 1995., p. 6 –shown 0.33 [3] ILO-WHO International Chemical Safety Cards (ICSCs) - pKa
- pKa= 4.88[6]
- Vapor pressure
- Vapor pressure, kPa at 20 °C: 0.39[3]
7 values
2 of 4 sources agree on it (most common value).
Value As written Source 2.9 mmHg 2.9 mmHg at 68 °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. 10 mmHg 10 mmHg at 103.5 °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. 3.3 mmHg Vapor pressure: 3.3 mm Hg at 27.6 °C [6] Hazardous Substances Data Bank (HSDB)cites Bingham, E.; Cohrssen, B.; Powell, C.H.; Patty's Toxicology Volumes 1-9 5th ed. John Wiley & Sons. New York, N.Y. (2001)., p. V5: 691 20 mmHg Vapor pressure: 20 mmHg at 125 °F [6] Hazardous Substances Data Bank (HSDB)cites Meister, R.T., Sine, C. (eds) Crop Protection Handbook Volume 92, Willoughby, OH, 2006., p. D-349 3.53 mmHg 3.53 mm Hg at 25 °C [6] Hazardous Substances Data Bank (HSDB)cites Daubert, T.E., R.P. Danner. Physical and Thermodynamic Properties of Pure Chemicals Data Compilation. Washington, D.C.: Taylor and Francis, 1989. 2.9 mmHgshown Vapor pressure, kPa at 20 °C: 0.39 [3] ILO-WHO International Chemical Safety Cards (ICSCs) 10 mmHg 10 [mm Hg] @39.700000000000003 °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
- 52 °C (126 °F) (Closed cup)[6]
5 values
3 of 5 sources agree on it (most common value).
Value As written Source 54 °C 130 °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. 52 °Cshown 126 °F (52 °C) (Closed cup) [6] Hazardous Substances Data Bank (HSDB)cites Fire Protection Guide to Hazardous Materials. 13 ed. Quincy, MA: National Fire Protection Association, 2002., p. 325-100 54 °C 54 °C c.c., 57 °C o.c. [3] ILO-WHO International Chemical Safety Cards (ICSCs) 52 °C 126 °F [4] Occupational Safety and Health Administration (OSHA) 52 °C 126 °F [5] The National Institute for Occupational Safety and Health (NIOSH) - Autoignition temperature
- 465 °C (870 °F)[6]
3 values
2 of 3 sources agree on it (most common value).
Value As written Source 466 °C 870 °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. 466 °Cshown 870 °F (465 °C) [6] Hazardous Substances Data Bank (HSDB)cites Fire Protection Guide to Hazardous Materials. 13 ed. Quincy, MA: National Fire Protection Association, 2002., p. 325-100 485 °C 485 °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
- 5
- Rings
- 0
- Aromatic rings
- 0
- Fraction sp³ carbons (Fsp3)
- 0.67
- H-bond donors
- 1
- H-bond acceptors
- 1 computed here · PubChem 2
- Rotatable bonds
- 1
- TPSA (Ų)
- 37.3
- Formal charge
- 0
- XLogP3
- 0.3 PubChem
- Complexity
- 40 PubChem
- Stereocenters
- None
- Double-bond geometry
- None specified
- Point group
- C1 of one 3D conformer with its hydrogens, by Athanor’s engine (as in the app)
Elemental analysis
- C48.64%
- H8.16%
- O43.19%
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
- 0.48 Crippen (Wildman and Crippen 1999)
- log S (water solubility)
- -0.54 ESOL (Delaney 2004), log mol/L
- Synthetic accessibility
- 1.64 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)
Drug-likeness: Lipinski’s rule of five
- Molecular weight ≤ 500: 74.08
- log P ≤ 5 (Crippen): 0.48
- H-bond donors ≤ 5: 1
- 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].
- Corrosive
- H314Causes severe skin burns and eye damage
Precautionary statements: P260, P264, P280, P301+P330+P331, P302+P361+P354, P304+P340, P305+P354+P338, P316, P321, P363, P405, P501
View all classifications (3)
- [8] Regulation (EC) No 1272/2008 of the European Parliament and of the Council · DangerH314
- [9] European Chemicals Agency (ECHA) · 2,683 reports · DangerH226, H314, H318, H335
- [9] European Chemicals Agency (ECHA) · 120 reportsThis chemical does not meet GHS hazard criteria for 100% (120 of 120) of all reports.
Exposure limits
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]
- Excerpt from ERG Guide 153 [Substances - Toxic and/or Corrosive (Combustible)]: Refer to the "General First Aid" section. Specific First Aid: For corrosives, in case of contact, immediately flush skin or eyes with running water for at least 30 minutes. Additional flushing may be required. Removal of solidified molten material from skin requires medical assistance. (ERG, 2024)[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: · 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]
Storage
- Fireproof. Separated from strong oxidants and strong bases. Store only in original container. Store in an area without drain or sewer access.[3]
- Outside or detached storage is preferred. Store in a cool, dry, well-ventilated location.[6]
- Ordinary steel is totally unsuitable for the handling of propionic acid. Aluminum is only resistant at room temperature and to anhydrous, concentrated propionic acid; at higher temperature corrosiveness toward aluminum varies with the concentration of acid. Thus the corrosion maximum for 50 °C lies at 75 % acid, whereas there are two maxima at the boiling point, a weaker one at 1 % and a strong one at 99.8 % acid.[6]
- Copper and copper alloys are stable toward propionic acid up to its boiling point, but only if the solutions are free from air or oxidizing substances. ... Containers made of aluminum with a purity of 99.5 % (DIN no. 3.0255) or alloyed steels (DIN no. 1.4541/UNS no.: S 30 400 and 1.4571/S 31 600) are suitable for storing pure propionic acid. Aluminum is unstable toward aqueous propionic acid. Polyethylene containers can be used for temporary storage of propionic acid and as small packing drums. Plastics are not recommended for long-term storage.[6]
Incompatibilities
Safety data sheets on the supplier’s page: Sigma-Aldrich, Thermo Fisher Scientific, MP Biomedicals.
Always read the supplier’s safety data sheet before working with it.
Spectra
- NMRHazardous Substances Data Bank (HSDB) · NMRShiftDB
- 1H NMRHuman Metabolome Database (HMDB) (Varian · 500 MHz · Water) · Human Metabolome Database (HMDB) (JEOL · 90 MHz · CDCl3) · Human Metabolome Database (HMDB) (Bruker · D2O) · SpectraBase (BRUKER AC-300)
- 13C NMRHuman Metabolome Database (HMDB) (Bruker · 125 MHz · Water) · Human Metabolome Database (HMDB) (400 MHz · H2O) · Human Metabolome Database (HMDB) (Varian · 25.16 MHz · CDCl3) · Human Metabolome Database (HMDB) (Bruker · D2O) · SpectraBase
- 17O NMRSpectraBase
- 1H-1H NMRHuman Metabolome Database (HMDB)
- 1H-13C NMRHuman Metabolome Database (HMDB) (Bruker · 600 MHz · Water)
- GC-MSHuman Metabolome Database (HMDB) (EI-B · positive) · Human Metabolome Database (HMDB) (EI-B · positive) · Human Metabolome Database (HMDB) (EI-B · positive) · MassBank of North America (MoNA) (HITACHI RMU-6M · EI-B · positive) · MassBank of North America (MoNA) (HITACHI M-80B · EI-B · positive) · MassBank of North America (MoNA) (HITACHI M-80B · EI-B · positive)
- MS-MSHuman Metabolome Database (HMDB) (EI-B (HITACHI RMU-6M) · Positive) · Human Metabolome Database (HMDB) (EI-B (HITACHI M-80B) · Positive) · Human Metabolome Database (HMDB) (LC-ESI-QQ (API3000, Applied Biosystems) · Negative) · Human Metabolome Database (HMDB) (LC-ESI-QQ (API3000, Applied Biosystems) · Negative) · Human Metabolome Database (HMDB) (LC-ESI-QQ (API3000, Applied Biosystems) · Negative) · Human Metabolome Database (HMDB) (LC-ESI-QQ (API3000, Applied Biosystems) · Negative)
- LC-MSMassBank Europe (API3000, Applied Biosystems · LC-ESI-QQ · NEGATIVE) · MassBank Europe (API3000, Applied Biosystems · LC-ESI-QQ · NEGATIVE) · MassBank Europe (API3000, Applied Biosystems · LC-ESI-QQ · NEGATIVE) · MassBank Europe (API3000, Applied Biosystems · LC-ESI-QQ · NEGATIVE) · MassBank of North America (MoNA) (API3000, Applied Biosystems · LC-ESI-QQ · negative) · MassBank of North America (MoNA) (API3000, Applied Biosystems · LC-ESI-QQ · negative)
- Other MSHazardous Substances Data Bank (HSDB) · MassBank Europe (HITACHI RMU-6M · EI-B · POSITIVE) · MassBank Europe (HITACHI M-80B · EI-B · POSITIVE) · MassBank of North America (MoNA) (ESI-Orbitrap · positive) · MassBank of North America (MoNA) (ESI-Orbitrap · positive) · MassBank of North America (MoNA) (ESI-Orbitrap · positive)
- UVHazardous Substances Data Bank (HSDB)
- IRHazardous Substances Data Bank (HSDB)
- FTIRSpectraBase (CAPILLARY CELL: NEAT)
- ATR-IRSpectraBase (Bruker Tensor 27 FT-IR · ATR-Neat (DuraSamplIR II))
- Near IRSpectraBase (BRUKER IFS 88 · NIR Spectrometer= INSTRUMENT PARAMETERS=INST=BRUKER,RSN=8883,REO=2,CNM=HEI,ZFF=2)
- Vapor Phase IRSpectraBase (Bruker IFS 85 · Gas-GC)
- RamanSpectraBase (Bruker MultiRAM Stand Alone FT-Raman Spectrometer · FT-Raman)
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]MassBank of North America (MoNA) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
- [15]NIST Mass Spectrometry Data Center · Linked only · via PubChem · retrieved 2026-10-14
- [16]MassBank Europe · 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.