IUPAC Name to Structure
Type a systematic IUPAC name and get the chemical structure back — SMILES, InChI, InChIKey, molecular formula and a drawn structure image. Parsing is done by OPSIN, with PubChem as a fallback for common and trivial names.
How it works
The name is first sent to OPSIN (Open Parser for Systematic IUPAC Nomenclature), a rule-based parser from the University of Cambridge that reads systematic nomenclature directly — no dictionary lookup. If OPSIN cannot interpret the name (common for trivial names such as “aspirin” or “caffeine”), the browser queries PubChem directly, which maintains a large curated name-to-structure index.
What OPSIN handles well
- Substitutive names —
2-chloro-4-nitrobenzoic acid - Fused ring systems —
quinoline,naphthalene - Stereochemistry —
(2R)-2-hydroxypropanoic acid - Esters, amides, salts and hydrates
- Multiplicative prefixes —
di,tri,tetra…
Limitations
- Trivial and trade names are not IUPAC names — OPSIN rejects them, so the PubChem fallback takes over.
- Badly formed names fail in both sources; check the spelling and locants.
- Biochemical names (enzymes, proteins, polymers) have no single structure.
- PubChem lookups run from your browser, so they require direct access to
pubchem.ncbi.nlm.nih.gov.
Frequently asked questions
Why does “aspirin” work but “2-acetoxybenzoic acid” also work?
“Aspirin” is a trivial name — OPSIN rejects it, PubChem resolves it by name lookup. “2-acetoxybenzoic acid” is systematic, so OPSIN parses it directly.
Is the structure validated?
Both sources return a parsed structure; the depiction you see is rendered from that SMILES by OpenBabel, so if the SMILES is wrong the drawing will be wrong too. Always check the structure against the name.
Can I convert the result further?
Yes — copy the SMILES into the format converter or the 3D structure generator.