IUPAC Name Conversion

ChemAudit can accept IUPAC names, common drug names, and trade names as input — converting them to SMILES automatically before validation. This makes it easy to validate molecules without knowing their SMILES notation.

How It Works

Auto-Detection

When you enter text in the input field, ChemAudit classifies it as one of three types:

Detection	Indicators	Example
SMILES	Contains (), [], =, #, @, /, \	CC(=O)Oc1ccccc1C(=O)O
IUPAC	Contains spaces, hyphens, or chemical suffixes (-ol, -ane, -ene, -acid, -one, -al, -amine, -amide, -yl, -ide, -oxy, -oic)	2-acetoxybenzoic acid
Ambiguous	Purely alphabetic, ≥4 characters, no clear indicators	aspirin

An input type badge appears below the input field showing the detected type (e.g., "Detected: IUPAC name"). When detection is ambiguous, you can use force-override buttons to specify the format manually.

Conversion Pipeline

IUPAC names are converted to SMILES using a two-tier approach:

1. OPSIN (primary) — Open Parser for Systematic IUPAC Nomenclature. Runs locally via Java, fast and works offline. Handles systematic IUPAC names with high accuracy.

2. PubChem PUG REST (fallback) — If OPSIN cannot parse the name, ChemAudit queries the PubChem API to resolve common names and trade names.

The conversion source (OPSIN or PubChem) is reported in the results.

What Happens After Conversion

Once a name is converted to SMILES, validation proceeds normally — all tabs work as expected (Validation, Alerts, Scoring, Standardization, Database Lookup, Scoring Profiles). A conversion badge shows the original name and the converted SMILES for reference.

Using IUPAC Input

Web Interface

1. Enter a chemical name in the input field (e.g., aspirin or 2-acetoxybenzoic acid)
2. The input type badge shows "Detected: IUPAC name"
3. Click Validate
4. The conversion badge shows: aspirin → CC(=O)Oc1ccccc1C(=O)O (via PubChem)
5. All validation results are based on the converted SMILES

Placeholder Help

The input field shows: "Enter SMILES, InChI, or IUPAC name (e.g., aspirin)"

API

Send the name directly to the validation endpoint:

curl -X POST http://localhost:8001/api/v1/validate \
  -H "Content-Type: application/json" \
  -d '{
    "molecule": "aspirin",
    "format": "auto"
  }'

The response includes an input_interpretation field with conversion details:

{
  "status": "completed",
  "input_interpretation": {
    "detected_as": "iupac",
    "original_input": "aspirin",
    "converted_smiles": "CC(=O)Oc1ccccc1C(=O)O",
    "conversion_source": "pubchem"
  },
  "molecule_info": {
    "input_smiles": "CC(=O)Oc1ccccc1C(=O)O",
    "canonical_smiles": "CC(=O)OC1=CC=CC=C1C(O)=O",
    "inchikey": "BSYNRYMUTXBXSQ-UHFFFAOYSA-N"
  },
  "overall_score": 95,
  "issues": []
}

You can also force the input type:

curl -X POST http://localhost:8001/api/v1/validate \
  -H "Content-Type: application/json" \
  -d '{
    "molecule": "morphine",
    "input_type": "iupac"
  }'

Supported Names

Name Type	Examples	Conversion Source
Systematic IUPAC	2-acetoxybenzoic acid, ethanol, propan-2-one	OPSIN
Common names	aspirin, caffeine, morphine	PubChem
Trade names	Tylenol, Advil (if in PubChem)	PubChem
CAS-style	Names resolvable by PubChem	PubChem

Limitations

• OPSIN requires Java: The Docker image includes a Java JRE. For local development, ensure Java is installed and OPSIN_JAR_PATH is configured.
• PubChem fallback requires internet: If OPSIN cannot parse the name and no internet connection is available, conversion will fail.
• Obscure names may fail: Very specialized or proprietary names not in PubChem's database cannot be resolved.
• Ambiguous names: Some short names may be ambiguous between SMILES and IUPAC. Use the force-override buttons or set input_type in the API to resolve.
• PubChem rate limits: The PubChem API has usage limits. For batch conversion of many names, consider pre-converting using a dedicated tool.

Verify Conversions

Always verify that the converted SMILES matches your intended molecule, especially for ambiguous or common names that may map to unexpected structures.

Next Steps

• Single Validation — Full validation features for converted molecules
• Database Integrations — Cross-reference converted molecules against databases
• Batch Processing — Process datasets (batch input uses SMILES columns)