1. Hydrocarbons
Saturated
Alkanes (Chapter 2)
Unsaturated
Alkenes (Chapters 5-6)
Alkynes (Chapter 7)
Arenes
(Chapters 21-22)

3. Systematic Nomenclature of Alkanes developed by the
International Union of Pure and Applied Chemistry (IUPAC)
Let’s look at a sample name and see how things are done.

4. Find the longest continuous carbon chain in the compound.
Step 1
Find the longest continuous carbon chain in the compound.
The number of carbons in this backbone determines the root.
If there are two or more chains of equal length, choose the one
with more branches.
Let’s look at the steps we should follow.
Let’s try a few examples of finding the longest chain.

5. pent- or incorrect correct more branches oct-
The longest chain is not necessarily the horizontal one. Examine the compound carefully.
oct-

6. Number the carbons in the root chain. Start from the end
Step 2
Attach suffix
-ane for an alkane
pentane
Step 3
Number the carbons in the root chain. Start from the end
that gives the lower number to the carbon where the first
branch occurs. If a tie, then proceed to the second branch, etc.
Step 2 is all we need to name a straight chain alkane.
If there are branches, then we need to number the main chain.

8. Step 4 Name the groups. root + -yl
Note that a group is not complete by itself. It is a branch; it has one more bond – the one attached to the root chain.

9. Assemble the name: number-grouprootsuffix
Step 5
Assemble the name: number-grouprootsuffix
2-methylhexane
3-ethyl-2,5-dimethylhexane
Let’s try some examples.
For several identical groups, use di-, tri-, etc. Provide a number for each.
When more than one group, alphabetize them (not the prefix, dimethyl under m).

10. Some additional terminology
Sometimes the number of carbon groups attached to a carbon will affect its chemical reactions. So terminology to designate this has been developed.

11. FIGURE 6.5: PLOT OF ENERGY VERSUS DIHEDRAL ANGLE FOR CONFORMATIONS OF ETHANE.
Fig. 6-5, p. 188

13. ACTIVE FIGURE 6.7: PLOT OF ENERGY VERSUS DIHEDRAL ANGLE FOR CONFORMATIONS OF BUTANE.
Fig. 6-7, p. 191

14. FIGURE 6.8: CYCLOPROPANE. (A) BOND ANGLES, (B) ANGLE STRAIN, AND (C) TORSIONAL STRAIN.

15. FIGURE 6.9: CYCLOBUTANE.
Fig. 6-9, p. 196

17. Total Ring Strain (kcal/mol) Torsional Strain (kcal/mol)
Ring Size
Total Ring Strain (kcal/mol)
Torsional Strain (kcal/mol)
Angle Strain (kcal/mol) 3
26.7 6
20.7 4
26.0 8 18 5
6.5 7
6.3
9.6 9
12.6

20. Constitutional Isomers
Different compounds with the same molecular formula
Constitutional Isomers
Different compounds with the same molecular formula but a different connectivity
Stereoisomers
Different compounds with the same connectivity but different 3D arrangement