Chapter 10 Introduction to Organic
Chemistry: Alkanes
10.3
Alkanes with Substituents
1
Isomers of Butane
Isomers
• have the same
molecular formula.
• have different atom
arrangements.
• of butane (C4H10) are a
straight chain and a
branched chain.
2
Alkyl groups
Alkyl groups are
• alkanes that are missing one H.
• substituents attached to carbon chains.
• named with a –yl ending.
H C CH3 methyl
H
H H
H C C CH3 CH2 ethyl
H H
3
Naming Substituents
TABLE 10.6
In the IUPAC system,
• a carbon branch is
named as an alkyl
group.
• halogen atoms are
named as halo.
4
Alkanes with Substituents
CH3
CH3 CH CH3 methylpropane
methyl groups
CH3 CH3
CH3 CH CH2 CH CH3 2,4-dimethylpentane
5
Naming Alkanes
Give the name of CH3 CH3
CH3─CH─CH─CH3
STEP 1 Name the longest continuous chain.
CH3 CH3
CH3─CH─CH─CH3
butane
6
Naming Alkanes
Give the name of CH3 CH3
CH3─CH─CH─CH3
STEP 2 Number chain. CH3 CH3
CH3─CH─CH─CH3
1 2 3 4
STEP 3 Locate substituents and name.
2,3-dimethylbutane
7
Learning Check
Write the name of
Cl CH3
CH3─CH2─CH─CH─CH3
8
Solution
STEP 1 Longest chain is pentane.
STEP 2 Number chain from end nearest substituent.
Cl CH3
CH3─CH2─CH─CH─CH3
5 4 3 2 1
STEP 3 Locate substituents and name alphabetically.
3-chloro-2-methylpentane
9
Learning Check
Give the IUPAC name for each of the following:
A. CH3 CH3
| |
CH3─CH─CH2 ─CH─CH3
B. Cl CH3
| |
CH3─CH2─CH─CH2─C─CH2─CH3
|
Cl
10
Solution
A. CH3 CH3
| |
CH3─CH─CH2 ─CH─CH3 2,4-dimethylpentane
1 2 3 4 5
B. Cl CH3 more substituents = C3
| |
CH3─CH2─CH─CH2─C─CH2─CH3
|
Cl
7 6 5 4 3 2 1
3,5-dichloro-3-methylheptane
11
Learning Check
Draw the condensed structural formula for
2-bromo-4-chlorobutane.
12
Solution
2-bromo-4-chlorobutane
STEP 1 Longest chain has 4 carbon atoms.
C─C─C─C
STEP 2 Number chain and add substituents.
Br
C ─ C ─ C ─ C ─ Cl
1 2 3 4
STEP 3 Add hydrogen to complete 4 bonds to each C.
Br
CH3─CH─CH2─CH2─Cl
13
Naming Cycloalkanes with
Substituents
The name of a substituent is placed in front of the
cycloalkane name.
methylcyclobutane CH3
chlorocyclopentane Cl
14
Learning Check
Name each of the following.
1. CH3
CH2─CH3
2.
15
Solution
Name each of the following.
1. methylcyclopropane
2. ethylcyclohexane
16
