Organic Chemistry 271
HC
H
H
C
H
H
C
H
H
C
H
H
HC
H
H
CC
H
H
C H
H
H
HHC
H
H
C
C
H
C
H
H
H
H
H H C
H
H
H
HHC
Pentane 2-Methylbutane 2,2-Dimethylpropane
C
H
H
H
Figure 18.3 Structural isomers of C 5 H 12.
Here is a practice problem. Name the following compound:
Answer: 5-ethyl-2,2-dimethylnonane
Solution:
First, pick the longest chain. This is bold-faced in the diagram below. The carbons are
attached by single bonds, so this is an alkane. Because the longest chain has nine carbons,
it is a nonane.
Next, the longest chain should be numbered from one end to the other with the lowest
number(s) going to the branches. For the above example the numbering of the chain
(bold-face carbon atoms) would be:
12 3 4 5
6
789
Once these numbers have been assigned, do not alter them later.
H
H
H
HHCH H HHC HH H
HH
H
H CC CH
HHH
CCCCCCCH
HCHH H H H H
H
H HCHH H H H H
HCCC
C
CCC
C
CH
H H H
H
HH H
HH
H H
HH H
CCC
H HH