Everything Science Grade 12

CHAPTER 1. ORGANICMOLECULES 1.7

Example 4: Naming the alkanes

QUESTION

Give the IUPAC name for the following compound:

CH

CH 3

H

C

H

H

C C

H

CH 2

CH 3

H

H

H

SOLUTION

Step 1 : Identify the functionalgroup

The compound is an alkane and will have the suffix -ane.

Step 2 : Find the longest carbon chain and number the carbons in the

longest chain.

There are six carbons inthe longest chain if theyare numbered

as shown below. The prefix for the compound ishex-.

H C(5)

CH3(6)

H

C(4)

H

H

C(3) C

H

CH2(2)

CH3(1)

H

H

H

Step 3 : Look for any branchedgroups, name them andgive their posi-

tion on the carbon chain

There is one methyl group attached to the mainchain. This is

attached to the third carbon atom.

Step 4 : Combine the elements of the compound’s name into a single

word in the order of branched groups; prefix; name ending according to

the functional group.

The compound’s nameis 3-methyl-hexane.