5 Steps to a 5 AP Chemistry 2019

272 ❯ STEP 4. Review the Knowledge You Need to Score High

3. The position where a particular substituent is attached to the chain is indicated by a
   location number. These numbers are assigned by consecutively numbering the carbons
   of the base hydrocarbon, starting at one end of the hydrocarbon chain. Choose the end
   that will result in the lowest sum of location numbers for the substituent groups. Place
   this location number in front of the substituent name and separate it from the name by
   a hyphen (for example, 2-methyl).


4. Place the substituent names with their location numbers in front of the base name of the
   alkane in alphabetical order. If there are identical substituents (two methyl groups, for
   example), give the location numbers of each, separated by commas using the common Greek
   prefixes (di-, tri-, tetra-, etc.) to indicate the number of identical substituent groups (i.e.,
   2,3-dimethyl). These Greek prefixes are not considered in the alphabetical arrangement.


5. The last substituent group becomes a part of the base name as a prefix.
   Studying Figures 18.1 and 18.2 may help you learn the naming of substituted alkanes.

CH 3 CH 2 CH 2 CH CH 2 CH 3

CH 2 CH 3

CH 3

CH

CH 3 CH 2 CH 2 CH CH 2 CH 3

CH 2

Ethyl group

CH 3

CH 3

CH

7654321 Heptane

Methyl group

4-ethyl-2-methylheptane

Figure 18.1 Naming an alkane.

CH 3 CH 2 CH 2 CH 2 C CH 2 CH 2 CH 3

CH 2

CH 2

CH 3

CH 3

CH 3

CH 2

CH 2

C

CH 3 CH 2 CH 2 CH 2 C CH 2 CH 2 CH 3

CH 2

CH 2

CH 3

CH 3

CH 3

CH 2

CH 2

C

Ethyl

968 7 54321

5-ethyl-3,3-dimethyl-5-propylnonane

Methyl

Methyl

Nonane

Propyl

Figure 18.2 Naming of another alkane.