MolDraw › 3D molecule models › Aspirin 3D model
Aspirin molecule model (C9H8O4)
Aspirin (acetylsalicylic acid) is a benzene ring carrying a carboxylic acid and an acetyl ester side by side (ortho). The ester transfers its acetyl group to the COX enzyme, which is how aspirin works.
Drag to rotate · pinch or scroll to zoom. 3D coordinates: PubChem conformer (CID 2244).
Aspirin at a glance
| Formula | C9H8O4 |
|---|---|
| Molar mass | 180.16 g/mol |
| IUPAC name | 2-acetyloxybenzoic acid |
| Atoms / bonds | 21 / 21 |
| H-bond donors / acceptors | 1 / 4 |
| XLogP3 | 1.2 |
| SMILES | CC(=O)OC1=CC=CC=C1C(=O)O |
| PubChem CID | 2244 |
What the 3D model of Aspirin shows
The model contains 21 atoms (13 heavy atoms and 8 hydrogens) joined by 21 bonds; in ball-and-stick mode every stick is one bond, and double or aromatic bonds are drawn as multiple sticks. Switch to space-filling to see the molecule as its electron cloud, scaled to van der Waals radii: this is the shape other molecules actually "feel". It can donate 1 and accept 4 hydrogen bonds, and its PubChem XLogP3 of 1.2 means it is fairly balanced between water and fat solubility. Its topological polar surface area is 63.6 Ų.
Shape and bond angles
| Atom(s) | Geometry / hybridisation | Angles & lengths |
|---|---|---|
| ring carbons | Trigonal planar, sp²; planar ring | 120° |
| ester and acid C=O carbons | Trigonal planar, sp² | ≈ 120° |
| acetyl CH₃ | Tetrahedral, sp³ | ≈ 109.5° |
Is Aspirin polar?
Polar but only slightly soluble in water (about 3 g/L). It is a weak acid with pKa ≈ 3.5.
Elemental composition of C9H8O4
| Element | Atoms | Mass (g/mol) | Mass % |
|---|---|---|---|
| Carbon (C) | 9 | 108.099 | 60.00% |
| Hydrogen (H) | 8 | 8.064 | 4.48% |
| Oxygen (O) | 4 | 63.996 | 35.52% |
Calculated from IUPAC standard atomic weights. Check any formula with the molar mass calculator.
Uses of aspirin
- Pain relief, fever and inflammation (NSAID)
- Low-dose aspirin to prevent blood clots
- Made from salicylic acid and acetic anhydride
Interesting facts
- Aspirin irreversibly acetylates a serine in COX-1 and COX-2 enzymes.
- It was first marketed by Bayer in 1899.
- Old aspirin can smell of vinegar because the ester slowly hydrolyses to acetic acid and salicylic acid.
Need identifiers (InChI, InChIKey), computed properties and file downloads? See the Aspirin structure reference page.
Drawing structures for your notes? MolDraw is a free online chemical structure editor for molecules, reactions and lab diagrams.
Open MolDraw editorFrequently asked questions
What functional groups are in aspirin?
A carboxylic acid, an ester (acetyl) and an aromatic benzene ring.
How is aspirin made?
By acetylating the OH group of salicylic acid with acetic anhydride, which also gives acetic acid.
What is the chemical formula and molar mass of aspirin?
Aspirin is C9H8O4 with a molar mass of 180.16 g/mol (PubChem CID 2244). It contains 21 atoms: 9 carbon, 8 hydrogen, 4 oxygen.
What is the IUPAC name of Aspirin?
The PubChem-computed IUPAC name is 2-acetyloxybenzoic acid.
How do I make a model of Aspirin?
Rotate the interactive model above to see how its 21 atoms connect, then copy it with a ball-and-stick kit: use the CPK colours shown (carbon grey or black, hydrogen white, oxygen red, nitrogen blue). For a school project, foam balls and toothpicks work well.