Branched alkanes

Branched hydrocarbons have four-part names:

locator + prefix + stem + suffix.

Counting carbons in the stem:
All carbons in the stem may not necessarily be in a line on the page.  Explore all of the stems by counting from CH3 to CH3.

Consider the five representations of the same molecule. The number of carbon atoms in the longest chain is four as is obvious for the two representations in the second row. Roll your mouse over the first three structures to see that it is true for these also.
 
(CH3)2CHCH2CH3CH3CH2CH(CH3)2

 
The prefix is the name given to the branch. This is the name of the corresponding alkane followed by -yl as shown below.  
 
carbon
number		name 
1methyl
2ethyl


The locator gives the number of the carbon in the longest chain bearing the branch, counting from the end of the chain closest to the branch point.

The name of the hydrocarbon shown above is 2-methylbutane.
Dr Sheila Woodgate
© The University of Auckland 2002