1. Chapter Organic Chemistry Alkanes and Aromatic Hydrocarbons
Cycloalkanes
Aromatic Hydrocarbons
Timberlake LecturePLUS 1999

2. Timberlake LecturePLUS 1999
Cycloalkanes
Cyclopropane CH2
CH CH2
Cyclobutane CH CH2
The is a group of alkanes that have a cyclic structure. These cycloalkanes contain a carbon chain that is in a ring. Each cycloalkane has a formula that is 2C less than the corresponding alkane. For example, propane is C3H8 whereas cyclopropane ic C3H6. Butane is C4H10 and cyclobutane is C4H10. The names of the cyclic structures use the prefix cyclo in from of the alkane name for the carbon chain.
Timberlake LecturePLUS 1999

3. Timberlake LecturePLUS 1999
More Cycloalkanes
Cyclopentane CH2
CH CH2
CH CH2
Cyclohexane
CH2
Timberlake LecturePLUS 1999

4. Naming Cycloalkanes with Side Groups
Number of Naming
side groups
One Side group name goes in front of the cycloalkane name.
Two Number the ring in the direction that gives the lowest numbers to the side groups.
Timberlake LecturePLUS 1999

5. Cycloalkanes with Side Groups
Timberlake LecturePLUS 1999

6. Timberlake LecturePLUS 1999
Learning Check Alk8
Timberlake LecturePLUS 1999

7. Timberlake LecturePLUS 1999
Solution Alk8
Timberlake LecturePLUS 1999

8. Aromatic Compounds and Benzene
Aromatic compounds contain benzene.
Benzene, C6H6 , is represented as a six carbon ring with 3 double bonds.
Two possible can be drawn to show benzene in this form.
Timberlake LecturePLUS 1999

9. Timberlake LecturePLUS 1999
Benzene Structure
The structures for benzene can also be written as a single structure where the alternating double bonds are written as a circle within the ring.
Benzene
structure
Timberlake LecturePLUS 1999

10. Aromatic Compounds in Nature and Health
Many aromatic compounds are common in nature and in medicine.
Timberlake LecturePLUS 1999

11. Naming Aromatic Compounds
Aromatic compounds are named with benzene as the parent chain. One side group is named in front of the name benzene.
methylbenzene chlorobenzene
(toluene)
Timberlake LecturePLUS 1999

12. Naming Aromatic Compounds
When two groups are attached to benzene, the ring is numbered to give the lower numbers to the side groups. The prefixes ortho (1,2), meta (1,3-) and para (1,4-) are also used.
Timberlake LecturePLUS 1999

13. Timberlake LecturePLUS 1999
Some Common Names
Some substituted benzene rings also use a common name. Then naming with additional more side groups uses the ortho-, meta-, para- system.
Timberlake LecturePLUS 1999

14. Timberlake LecturePLUS 1999
Learning Check Alk9
Select the names for each structure:
1. Chlorocyclohexane
2. Chlorobenzene
3. 1-chlorobenzene
1. 1,2- dimethylbenzene
2. Meta-dimethylbenzene
3. 1,3-dimethylbenzene
Timberlake LecturePLUS 1999

15. Timberlake LecturePLUS 1999
Solution Alk9
Select the names for each structure:
2. Chlorobenzene
2. Meta-dimethylbenzene
3. 1,3-dimethylbenzene
Timberlake LecturePLUS 1999

16. Learning Check Alk10
Write the structural formulas for each of the following:
A. 1,3-dichlorobenzene
B. Ortho-chloromethylbenzene

17. Solution Alk10
Write the structural formulas for each of the following:
A. 1,3-dichlorobenzene
B. Ortho-chloromethylbenzene