Aspirin
Properties
- Molecular formula
- C9H8O4
- Molar mass
- 180.16 g/mol
- Exact mass
- 180.0423 Da
- Density
- 1.4 g/mL
- Melting point
- 135 °C
- Boiling point
- 197–200 °C (at 7 Torr)
- pKa
- 3.49 (25 °C)
- Flash point
- 250 °C
- Water solubility
- 4.6 g/L (25 °C)
- logP
- 1.31Crippen estimate
- Polar surface area
- 63.6 Ų
- H-bond donors / acceptors
- 1 / 3
- Rotatable bonds
- 2
Acetylsalicylic acid - the first mass-produced synthetic drug (Bayer, 1899) and an irreversible covalent inhibitor of cyclooxygenase via acetylation of COX-1 Ser530. After a century as the canonical analgesic, low-dose aspirin remains a workhorse of secondary cardiovascular prevention; primary-prevention guidance has tightened. A March 2026 meta-analysis from West China Hospital of Sichuan University (10 RCTs, 124,837 participants) found no meaningful reduction in colorectal cancer or precursor lesions among average-risk adults, reinforcing the USPSTF 2022 reversal and the broader shift toward precision prevention rather than population-wide prophylaxis.
Hazards
- H302 Harmful if swallowed95.6% of notifiers
- H315 Causes skin irritation20.6% of notifiers
- H319 Causes serious eye irritation22.2% of notifiers
- H335 May cause respiratory irritation20% of notifiers
Aggregated from 315 ECHA notifications, via PubChem; a share says how many notifiers assign that statement.
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
Identifiers
50-78-2CC(=O)Oc1ccccc1C(=O)OBSYNRYMUTXBXSQ-UHFFFAOYSA-NInChI=1S/C9H8O4/c1-6(10)13-8-5-3-2-4-7(8)9(11)12/h2-5H,1H3,(H,11,12)Weigh it out
Type any one amount. The others follow from the molar mass and density.
Names and synonyms
141 names · show all
- Benzoic acid, 2-(acetyloxy)-
- Rhodine
- Salicylic acid acetate
- 2-(Acetyloxy)benzoic acid
- Aceticyl
- Acetilum acidulatum
- Acetophen
- Acetosal
- Acetosalic acid
- Acetosalin
- o-Acetoxybenzoic acid
- 2-Acetoxybenzoic acid
- Acetylin
- Acetylsal
- Acidum acetylsalicylicum
- Acylpyrin
- Aspirine
- Aspro
- Asteric
- A.S.A. Empirin
- Helicon
- Measurin
- Salacetin
- Salcetogen
- Saletin
- Xaxa
- Acetylsalicylic acid
- Asagran
- Rhonal
- Acenterine
- SP 189
- ASA
- Duramax
- Ecotrin
- Entrophen
- Enterosarine
- Neuronika
- Endydol
- Acetisal
- Colfarit
- Acisal
- Dolean pH 8
- AC 5230
- Acesal
- Polopiryna
- o-Carboxyphenyl acetate
- Triple-sal
- Rheumintabletten
- Idragin
- Yasta
- Benaspir
- Temperal
- Bialpirina
- 2-Carboxyphenyl acetate
- Globentyl
- Novid
- Globoid
- O-Acetylsalicylic acid
- Micristin
- Acetysal
- Acetard
- Medisyl
- Caprin
- ECM
- Empirin
- Istopirin
- o-(Acetyloxy)benzoic acid
- Endosprin
- Aspro clear
- Kapsazal
- Aspropharm
- Zorprin
- Aspirina 03
- Rhodine NC RP
- Acesan
- Miniasal
- Aspirin protect 100
- Aspirin protect 300
- Melhoral
- Claradin
- Coricidin
- Contrheuma retard
- Aspalon
- Aspergum
- Bialpirinia
- Enterophen
- Solpyron
- Easprin
- Darvon compound
- Extren
- Gelprin
- Nu-seals
- Supac
- Acetyonyl
- Persistin
- Acimetten
- Coricidin D
- Aspirdrops
- Salycylacetylsalicylic acid
- Ascriptin
- Crystar
- Ascoden 30
- Asatard
- Entericin
- Albyl E
- Adiro
- Cardioaspirina
- Ewin
- Dominal
- Toldex
- NSC 27223
- NSC 406186
- Ascolong
- Aspirin-direkt
- Asaflow
- Trombyl
- Magnecyl
- Lysoprin (pharmaceutical)
- Salospir
- Rhodine 2312
- Astrix
- Mycropyrin
- Colsprin
- Ecosprin
- Cardioaspirin
- Anopyrin
- Ecopirin
- ThromboASS
- Coraspin
- Cardiomagnyl
- Angettes 75
- Bayaspirin
- IWN 11
- Rhodine 3118
- Rhodine 3220
- Zosprin
- Aspirina
- Rivo
- Durlaza
- Rodine 3220
- Rhodine 3040
Safety data sheets
One stored sheet lists this compound in section 3, matched by the CAS number 50-78-2. Each row opens the sheet with its composition and PDF.
Work with Aspirin
Stereoisomers, salts and isotopologues
The same compound in another form: other stereochemistry, a salt or hydrate, the free acid or base, or an isotope-labelled version.
Similar compounds
Tanimoto similarity of circular fingerprints over the whole catalogue. All similar compounds