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Chemistry 130

Library Resources for Identifying Unknowns | Nomenclature Resources | TA Hours | Handouts and Guides | Related Links

Finding Parent Unknowns

Even though it is not comprehensive, you may want to begin by using a classic handbook called the CRC Handbook of Tables for Organic Compound Identification. Print copies are also available, on reserve in the Swain Library. Published in 1967, it is a quick and easy place to look for unknowns because the book is divided by class of compound. Within a class, compounds are arranged by liquid or solid. Then within liquid or solid, compounds are arranged by increasing melting or boiling point. The same row for a compound contains melting or boiling point values for some common derivatives. If no derivative data is included it does not mean that this derivative does not exist, it simply means that they did not have the data in hand when they compiled this handbook. Because structures diagrams are not included, consult another handbook such as Combined Chemical Dictionary (CCD), Properties of Organic Compounds (POC), or the CRC Handbook of Chemistry and Physics. Section 2 of the CRC covers basic nomenclature.

There are many different ways to search chemistry handbooks to find your unknown parent compound. Methods include searching by physical properties such as melting point, boiling point, and molecular weight, as well as searching by molecular formula, heteroatoms present in the molecular formula, and chemical substructures as small as a functional group.

All unknown “parent” compounds for the course are located in either the CCD Database or the POC Database. Both databases are part of CHEMnetBASE. Search instructions and other information to help you search these two databases is below.

Combined Chemical Dictionary Database (CCD) via CHEMnetBASE

CCD via CHEMnetBASE for Identifying Unknowns (pdf) (Change scale in lower left corner to 100%)
List of Abbreviations Used in CCD
CCD: Help File

Properties of Organic Compounds (POC) via CHEMnetBASE

POC via CHEMnetBASE for Identifying Unknowns (pdf) (Change scale in lower left corner to 100%)
Data Fields and Field Descriptions
List of Abbreviations Used in POC
POC: Help File

Getting additional information about a parent compound: The easiest way to find additional information is to search by CAS Registry Number in other handbooks. CAS Registry Numbers are included in both the CCD and POC and they look like this: 95-20-1. Handbooks to consult for additional information include:

The Merck Index contains excellent descriptions on the physical appearance of compounds. It also contains information on derivatives. Merck is also available as a networked CD-ROM in the Swain and Green Libraries. Print copies are also located in Swain’s reference room and on reserve in the Swain Library. Merck contains references to the journal articles where information on a compound was originally published.

Beilstein Crossfire contains up to 350 different types of information about compounds and is very useful because all of the data in it has been reviewed and evaluated. It is available at the Swain Library and the software search “client” software can also be downloaded to your computer. We do not recommend using Beilstein to identify parent compounds. Beilstein contains 8 million compounds and it is easy to drown in data and to spend lots of time sorting through search results. Instead, we recommend that you use Beilstein to find additional information about a parent compound and to find derivatives. Beilstein is the one of the most complete sources for derivative information. Like The Combined Chemical Dictionary Database and the Merck Index, Beilstein contains references to the original journal article where the data was originally published.