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
1---2name: cas3description: Look up chemicals in CAS Common Chemistry (name, CAS RN, SMILES, InChI; ~500k compounds)4---56# CAS Common Chemistry78Query [CAS Common Chemistry](https://commonchemistry.cas.org/) for compound names, CAS Registry Numbers®, molecular formula, mass, SMILES, InChI, and experimental properties. Covers nearly 500,000 compounds (CC BY-NC 4.0).910**API access:** Request a free API key at [https://www.cas.org/services/commonchemistry-api](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`.1112## Overview1314- Search by compound name (supports trailing wildcard, e.g. `aspirin*`), CAS RN, SMILES, or InChI/InChIKey15- Get detail: name, formula, mass, InChI, SMILES, experimental properties (e.g. melting point, density)16- Reference: `references/cas-common-chemistry-api.md`1718## Usage1920### Search by name21```bash22python3 {baseDir}/scripts/cas_search.py --query "aspirin"23```2425### Get detail by CAS Registry Number26```bash27python3 {baseDir}/scripts/cas_search.py --cas "50-78-2"28```2930### Search with wildcard31```bash32python3 {baseDir}/scripts/cas_search.py --query "atrazin*"33```3435### JSON output36```bash37python3 {baseDir}/scripts/cas_search.py --query "caffeine" --format json38```3940## Parameters4142| Parameter | Description | Default |43|-----------|-------------|---------|44| `--query` | Name, SMILES, or InChI (name supports trailing *) | - |45| `--cas` | CAS Registry Number (e.g. 50-78-2) | - |46| `--max-results` | Max search results | 10 |47| `--format` | summary, detailed, json | summary |4849## Output5051- **Summary:** CAS RN, name, formula, molecular mass, SMILES52- **Detailed:** Adds InChI, InChIKey, experimental properties, synonyms53- **JSON:** Full API response5455## Notes5657- Request API access: [CAS Common Chemistry API](https://www.cas.org/services/commonchemistry-api)58- Optional: set `CAS_API_KEY` or config file if CAS requires authentication
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