Research Guides: Chemical and Physical Property Information: Try First

Searching for a Compound

There are many ways you can describe a compound in order to search for it within a database. Consider your options and what types of descriptions the particular database will accept. If you get zero results, try another way before moving on to another resource.

Chemical name/synonyms
Common/trivial name
Molecular formula
Empirical formula
Structure
CAS Registry Number

For example, consider ethanol:

ethanol
ethyl alcohol
ethyl hydroxide
C2H6O
H3C-CH2-OH
CAS# 64-17-15

Start with these online resources

These resources collect information on the most commonly encountered compounds and their most basic properties. If you are not finding an entry under the first chemical name that you try, try another synonym for that same compound or in the case of some of the sources, draw the structure of the compound you are looking for. Then try one of the more comprehensive sources (other tabs) if you are still having trouble finding the data you need.

CHEMnetBASE
A collection of more robust resources targeted toward specific compounds (natural products, drugs, organic compounds, polymers, etc.) or you can choose to search the Combined Chemical Dictionary of over 500,000 substances. [Allows structure searching.]
ChemSpider
ChemSpider is a free chemical structure database providing fast text and structure search access to over 29 million structures from hundreds of data sources. Starting from this page with your Career Account is suggested because it will also link to available information in Merck Index and articles in RSC journals to which Purdue subscribes.
CRC Handbook of Chemistry and Physics
A good place to start. Besides data, find basic constants, units and conversion factors; general health and safety information; and mathematical tables, etc. Search substance name, molecular formula, or full-text, or browse text and tables. [Allows structure searching.]
Knovel
Knovel provides numerical and tabular data from over 900 leading engineering and science handbooks and resources. Some tables and graphs are interactive.
Merck Index
Descriptive information on 10,000+ chemicals, drugs (human and veterinary), and biologicals. Each entry lists synonyms for drug names (trade, chemical, generic, and research codes), CAS Registry Numbers, physical data, patent information, uses, toxicity, and bibliographic citations on synthesis, pharmacology, and toxicology. [Allows structure searching.]

NIST Chemistry WebBook
Database of critically-evaluated physical property data from collections maintained by the National Institute of Standards (NIST) Standard Reference Data Program and outside contributors. [Allows structure searching.] You can search for data on specific compounds based on name, chemical formula, CAS registry number, molecular weight, chemical structure, or selected ion energetics and spectral properties.
Sigma-Aldrich Chem Product Central
Sales information, but also basic property data (including, often, various spectra) and key references to other important data resources, including the Beilstein Handbuch. Search in the top right. [Allows structure searching.]

And what about Wikipedia and Wolfram Alpha?

Both Wikipedia and Wolfram Alpha can be quick and easy to seach when it come to chemical and physical properties. But before you use these resources, please consider the following when searching each source.

Wikipedia: WikiProject Chemicals
This WikiProject is meant to standardize information about chemicals found on Wikipedia and to improve the quality of the information available. A compounds rating indicates how reliable the information is. For example, for the over 8000 compounds found in Wikipedia, nearly 2500 are unassessed, meaning the information cannot be verified. Common compounds may have reliable info, but it is best to verify the data found with another source listed above, especially for more uncommon substance
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Also note that currently (Sept 2010) only 17 compounds meet the highest level of quality by Wikipedia standards! Make sure the databox for your compound has a green check, meaning the data has been validated. Also note that many of the Wikipedia articles cite the suggested resources listed above, so why not start with them in the first place?
Wolfram Alpha
WA contains a wide variety of data on many chemical compounds. However, WA's major flaw is that it DOES NOT tell you the specific source of the data presented. WA claims to have a proprietary database of data gathered from various sources. While these sources are often listed, you can not be certain where a particular boiling point or heat capacity came from. When you need to cite an exact source or justify your data from a reliable & credible source, try one of the other resource above instead