Aspirin
Athanor · official
C9H8O4 · 180.16 g/mol
IUPAC name: 2-acetyloxybenzoic acid
Also called acetylsalicylic acid, ASA, Bayer, Disprin, NSAID
WarningHarmful if swallowed · Causes skin irritation · Causes serious eye irritation · May cause respiratory irritationNames and identifiers
- IUPAC name
- 2-acetyloxybenzoic acid
- Synonyms
- acetylsalicylic acid, ASA, Bayer
+ 40 more
Disprin, NSAID, ACETYLSALICYLIC ACID, 2-Acetoxybenzoic acid, 2-(Acetyloxy)benzoic acid, Acylpyrin, O-Acetylsalicylic acid, o-Acetoxybenzoic acid, Acenterine, Acetophen, Ecotrin, Salicylic acid acetate, Aceticyl, Acetosalin, Polopiryna, Aspirdrops, Pharmacin, Premaspin, Salcetogen, Acetonyl, Benaspir, Empirin, Endydol, Measurin, Rhodine, Saletin, Temperal, Adiro, Ecolen, Acetosalic acid, Rheumintabletten, Solprin acid, o-Carboxyphenyl acetate, Acidum acetylsalicylicum, Benzoic acid, 2-(acetyloxy)-, 2-acetyloxybenzoic acid, Enterosarine, Acetisal, Acetylsal, Aspirine
- Molecular formula
- C9H8O4
- Empirical formula
- C9H8O4
- Molecular weight
- 180.16 g/mol
- Exact mass
- 180.04226
- CAS number
- 50-78-2
- PubChem CID
- 2244
- Canonical SMILES
- CC(=O)OC1=CC=CC=C1C(=O)O
- Isomeric SMILES
- CC(=O)OC1=CC=CC=C1C(=O)O
- InChI
- InChI=1S/C9H8O4/c1-6(10)13-8-5-3-2-4-7(8)9(11)12/h2-5H,1H3,(H,11,12)
- InChIKey
- BSYNRYMUTXBXSQ-UHFFFAOYSA-N
- Molfile
Names, InChI and the identifiers from PubChem, retrieved 2026-10-14.
Physical properties
TemperaturePressureDensity
- Appearance
- Colorless to white, crystalline powder.[5]
5 values
From Hazardous Substances Data Bank (HSDB), the most authoritative source here.
Value As written Source – Acetylsalicylic acid appears as odorless white crystals or crystalline powder with a slightly bitter taste. (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. – COLOURLESS-TO-WHITE CRYSTALS OR WHITE CRYSTALLINE POWDER WITH CHARACTERISTIC ODOUR. [2] ILO-WHO International Chemical Safety Cards (ICSCs) – Odorless, colorless to white, crystal-line powder. [3] Occupational Safety and Health Administration (OSHA) – Odorless, colorless to white, crystal-line powder. [aspirin] [Note: Develops the vinegar-like odor of acetic acid on contact with moisture.] [4] The National Institute for Occupational Safety and Health (NIOSH) –shown Colorless to white, crystalline powder. [5] 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) - Odor
- Odorless [Note: Develops the vinegar-like odor of acetic acid on contact with moisture].[5]
- Melting point
- 135 °C[2]
4 values
4 of 4 sources agree on it (most common value).
Value As written Source 135 °C 275 °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. 135 °Cshown 135 °C [2] ILO-WHO International Chemical Safety Cards (ICSCs) 135 °C 275 °F [3] Occupational Safety and Health Administration (OSHA) 135 °C 275 °F [4] The National Institute for Occupational Safety and Health (NIOSH) - Boiling point
- 140 °C (284 °F) at 760 mmHg (decomposes) (NTP, 1992)[1]
3 values
3 of 3 sources agree on it (most common value).
Value As written Source 140 °Cshown 284 °F at 760 mmHg (decomposes) (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. 140 °C 284 °F (decomposes) [3] Occupational Safety and Health Administration (OSHA) 140 °C 284 °F (Decomposes) [4] The National Institute for Occupational Safety and Health (NIOSH) - Density
- 1.35[4]
4 values
2 of 4 sources agree on it (most common value).
Value As written Source – 1.4 (NTP, 1992) - Denser than water [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. – 1.4 g/cm³ [2] ILO-WHO International Chemical Safety Cards (ICSCs) – 1.35 [3] Occupational Safety and Health Administration (OSHA) –shown 1.35 [4] The National Institute for Occupational Safety and Health (NIOSH) - Solubility in water
- Solubility in water, g/100ml at 15 °C: 0.25 (poor)[2]
4 values
From ILO-WHO International Chemical Safety Cards (ICSCs), the most authoritative source here.
Value As written Source – less than 1 mg/mL at 73 °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. – In water, 4,600 mg/L at 25 °C [5] Hazardous Substances Data Bank (HSDB)cites Yalkowsky SH, Dannenfelser RM; Aquasol Database of Aqueous Solubility. Version 5. College of Pharmacy, University of Arizona - Tucson, AZ (1992) –shown Solubility in water, g/100ml at 15 °C: 0.25 (poor) [2] ILO-WHO International Chemical Safety Cards (ICSCs) – (77 °F): 0.3% [4] The National Institute for Occupational Safety and Health (NIOSH) - log P
- 1.19[2]
2 values
2 of 2 sources agree on it (most common value).
Value As written Source – log Kow = 1.19 [5] 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. 54 –shown 1.19 [2] ILO-WHO International Chemical Safety Cards (ICSCs) - Vapor pressure
- 2.52 × 10⁻⁵ mmHg at 25 °C (calc)[5]
- Flash point
- 250 °C (482 °F, NTP 1992)[1]
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
- 13
- Rings
- 1
- Aromatic rings
- 1
- Fraction sp³ carbons (Fsp3)
- 0.11
- H-bond donors
- 1
- H-bond acceptors
- 3 computed here · PubChem 4
- Rotatable bonds
- 2 computed here · PubChem 3
- TPSA (Ų)
- 63.6
- Formal charge
- 0
- XLogP3
- 1.2 PubChem
- Complexity
- 212 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
- C60.00%
- H4.48%
- O35.52%
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
- 1.31 Crippen (Wildman and Crippen 1999)
- log S (water solubility)
- -1.99 ESOL (Delaney 2004), log mol/L
- Synthetic accessibility
- 1.58 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)
Drug-likeness: Lipinski’s rule of five
- Molecular weight ≤ 500: 180.16
- log P ≤ 5 (Crippen): 1.31
- H-bond donors ≤ 5: 1
- 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
Warning
Most widely reported: 315 company reports to ECHA. Source [6].
- Harmful or irritant
- H302Harmful if swallowed (95.6% of reports)
- H315Causes skin irritation (20.6% of reports)
- H319Causes serious eye irritation (22.2% of reports)
- H335May cause respiratory irritation (20% of reports)
Precautionary statements: P261, P264, P264+P265, P270, P271, P280, P301+P317, P302+P352, P304+P340, P305+P351+P338, P319, P321, P330, P332+P317, P337+P317, P362+P364, P403+P233, P405, P501
View all classifications (2)
- [6] European Chemicals Agency (ECHA)This chemical does not meet GHS hazard criteria for 0.3% (1 of 315) of reports.
- [6] European Chemicals Agency (ECHA) · 315 reports · WarningH302, H315, H319, H335
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]
- (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: Soap wash - If this chemical contacts the skin, wash the contaminated skin with soap and water. Breathing: Respiratory support Swallow: Medical attention immediately - If this chemical has been swallowed, get medical attention immediately.[4]
- Fresh air, rest. Refer for medical attention.[2]
- Rinse skin with plenty of water or shower. Refer for medical attention .[2]
Storage
Incompatibilities
Safety data sheets on the supplier’s page: Enamine, SynHet - Synthetic Heterocycles, Alfa Chemistry.
Always read the supplier’s safety data sheet before working with it.
Spectra
- NMRHazardous Substances Data Bank (HSDB) · NMRShiftDB
- 1H NMRHuman Metabolome Database (HMDB) (Bruker · 600 MHz · Water) · Human Metabolome Database (HMDB) (JEOL · 400 MHz · CDCl3) · SpectraBase (BRUKER AC-300)
- 13C NMRHuman Metabolome Database (HMDB) (50.18 MHz · CDCl3) · SpectraBase
- 1H-13C NMRHuman Metabolome Database (HMDB) (Bruker · 600 MHz · Water)
- GC-MSHuman Metabolome Database (HMDB) (GC-MS) · Human Metabolome Database (HMDB) (EI-B · positive) · Human Metabolome Database (HMDB) (CI-B · positive) · Human Metabolome Database (HMDB) (EI-B · positive) · Human Metabolome Database (HMDB) (GC-EI-TOF · positive) · Human Metabolome Database (HMDB) (GC-MS)
- MS-MSHuman Metabolome Database (HMDB) (Positive) · Human Metabolome Database (HMDB) (Negative) · Human Metabolome Database (HMDB) (Negative) · Human Metabolome Database (HMDB) (Quattro_QQQ · Positive) · Human Metabolome Database (HMDB) (Quattro_QQQ · Positive) · Human Metabolome Database (HMDB) (Quattro_QQQ · Positive)
- LC-MSMassBank Europe (QExactive Orbitrap HF-X (Thermo Scientific) · LC-ESI-QFT · POSITIVE) · MassBank Europe (maXis plus UHR-ToF-MS, Bruker Daltonics · LC-ESI-QTOF · NEGATIVE) · MassBank Europe (Q Exactive Plus Orbitrap Thermo Scientific · LC-ESI-QFT · POSITIVE) · MassBank Europe (Q Exactive Plus Orbitrap Thermo Scientific · LC-ESI-QFT · POSITIVE) · MassBank Europe (Q Exactive Plus Orbitrap Thermo Scientific · LC-ESI-QFT · POSITIVE) · MassBank Europe (Q Exactive Plus Orbitrap Thermo Scientific · LC-ESI-QFT · POSITIVE)
- Other MSHazardous Substances Data Bank (HSDB) · MassBank Europe (QExactive Orbitrap HF-X (Thermo Scientific) · LC-APCI-QFT · POSITIVE) · MassBank Europe (Unknown · EI-B · POSITIVE) · MassBank Europe (Unknown · CI-B · POSITIVE) · MassBank Europe (GCMS-2010 Plus, Shimadzu · EI-B · POSITIVE) · MassBank of North America (MoNA) (TQD, Waters · Flow-injection QqQ/MS · ESI)
- UVHazardous Substances Data Bank (HSDB)
- IRHazardous Substances Data Bank (HSDB)
- FTIRSpectraBase (NEAT)
- ATR-IRSpectraBase (Bio-Rad FTS · ATR-Neat (DuraSamplIR II))
- RamanHazardous Substances Data Bank (HSDB) · RRUFF Project · RRUFF Project · RRUFF Project · RRUFF Project · RRUFF Project
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]ILO-WHO International Chemical Safety Cards (ICSCs) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
- [3]Occupational Safety and Health Administration (OSHA) · Public domain (US DOL) · via PubChem · retrieved 2026-10-14
- [4]The National Institute for Occupational Safety and Health (NIOSH) · Public domain (US CDC) · via PubChem · retrieved 2026-10-14
- [5]Hazardous Substances Data Bank (HSDB) · Public domain (US NLM) · via PubChem · retrieved 2026-10-14
- [6]European Chemicals Agency (ECHA) · ECHA legal notice: reuse with acknowledgement · via PubChem · retrieved 2026-10-14
- [7]NMRShiftDB · Linked only · via PubChem · retrieved 2026-10-14
- [8]Human Metabolome Database (HMDB) · Linked only · via PubChem · retrieved 2026-10-14
- [9]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
- [10]MassBank Europe · Linked only · via PubChem · retrieved 2026-10-14
- [11]MassBank of North America (MoNA) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
- [12]NIST Mass Spectrometry Data Center · Linked only · via PubChem · retrieved 2026-10-14
- [13]RRUFF Project · 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.