Basic Rules

Organic Nomenclature
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Rules for Organic Nomenclature

Following are some basic rules for naming organic compounds. To return to your place in Organic Nomenclature, move to the other browser window or close this window.

1. Find the main chain, the longest continuous chain of carbon atoms (also known as the trunk).

2. Modifiers, covalently bonded to the main chain are located by numbers, and named before the trunk.

3. Each modifier (or substituent, or side-chain group) gets its own number.

4. When more than one modifier is present, list them either in
a) alphabetical order (e for ethyl before m for methyl)
b) in complexity (increasing number of carbon atoms)

5. If identical modifiers are present, use the prefixes "di" (for two), "tri" (for three), "tetra" (for four).

6. The functional group is named using the special suffix for the particular class of compound.

7. See Prefixes and Suffixes or Common Names for more information on these topics.