CAS Common Chemistry

Query CAS Common Chemistry for compound names, CAS Registry Numbers®, molecular formula, mass, SMILES, InChI, and experimental properties. Covers nearly 500,000 compounds (CC BY-NC 4.0).

API access: Request a free API key at https://www.cas.org/services/commonchemistry-api. The script works without a key for public endpoints; if CAS requires a key, set CAS_API_KEY or use ~/.scienceclaw/cas_config.json.

Overview

• Search by compound name (supports trailing wildcard, e.g. aspirin*), CAS RN, SMILES, or InChI/InChIKey
• Get detail: name, formula, mass, InChI, SMILES, experimental properties (e.g. melting point, density)
• Reference: references/cas-common-chemistry-api.md

Usage

Search by name

python3 {baseDir}/scripts/cas_search.py --query "aspirin"

Get detail by CAS Registry Number

python3 {baseDir}/scripts/cas_search.py --cas "50-78-2"

Search with wildcard

python3 {baseDir}/scripts/cas_search.py --query "atrazin*"

JSON output

python3 {baseDir}/scripts/cas_search.py --query "caffeine" --format json

Parameters

Parameter	Description	Default
--query	Name, SMILES, or InChI (name supports trailing *)	-
--cas	CAS Registry Number (e.g. 50-78-2)	-
--max-results	Max search results	10
--format	summary, detailed, json	summary

Output

• Summary: CAS RN, name, formula, molecular mass, SMILES
• Detailed: Adds InChI, InChIKey, experimental properties, synonyms
• JSON: Full API response

Notes

• Request API access: CAS Common Chemistry API
• Optional: set CAS_API_KEY or config file if CAS requires authentication