Organic Names Functional Group Structures Hydrocarbons compounds  Elmhurst College
Root Name Position Numbers  Inorganic Groups  Chemistry Department
Functional Group Names Carbon Branches Final Name  Virtual ChemBook

 
 
 

 Hydrocarbon Branches

One or more carbons may be attached to the longest continuous chain as branches. The branch is located by a position number. Carbons are numbered so that the functional group has the lowest number. If there is no functional group present, then the first branch should have the lowest number.

The branch is named by dropping the "-ane" ending of the root then adding the "-yl" ending. The branch names precedes the main chain root name.

Examples:
One carbon: methane = methyl
Two carbons: ethane = ethyl
Three carbons: propane = propyl

Example top left - Branched Alkane:

At carbon 3 there is a one carbon branch = methyl.

At carbon 4 there is a two carbon branch = ethyl.

 Example lower left - Branched Pentene:

At carbon 2 there is a one carbon branch = methyl.

At carbon 4 there are two separate one carbon branches = methyl