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Research Guide for Chemistry: Databases

A guide to research resources for Chemistry

CAS Registry Numbers

What is a CAS Registry Number?

CAS Registry Numbers are unique identifiers assigned to specific substances by the Chemical Abstracts Service (CAS), department of the American Chemical Society. For example the CAS RN for aspirin is  50-78-2.

CAS Numbers are useful for substance searching in chemistry databases. A single search by CAS RN retrieves results for chemical names, synonyms, trade names, systematic names of the same substance. 

How do I find the CAS Registry Number?

If you know the chemical name you can find its CAS Number by searching in the following databases

NIST Chemistry WebBook

RSC ChemSpider

Contact your subject librarian if you need help in finding a CAS number, or substance searching.


The Key Chemistry Databases

The list of research databases in Chemistry includes:

Additional databases

Guides and Tutorials

For detailed online tutorials, videos, and guides on searching SciFinder and Reaxys
visit the following webistes: