1. Chapter 2 Alkanes: Nomenclature and an Introduction to Synthesis

2. Functional Groups
Functional group families are characterized by the presence of a certain arrangement of atoms called a functional group
A functional group is the site of most chemical reactivity of a molecule
The functional group is responsible for many of the physical properties of a molecule
Alkanes do not have a functional groups
Carbon-carbon single bonds and carbon-hydrogen bonds are generally very unreactive
Chapter 4

3. Summary of Important Families of Organic Compounds
Chapter 4

4. Summary (cont.)
Chapter 4

5. Classification of Hydrocarbons
Most organic compounds are derived from a group of compounds known as hydrocarbons because they are made up of only hydrogen and carbon.
Aliphatic hydrocarbons do not contain the benzene group, or the benzene ring.
aromatic hydrocarbons contain one or more benzene rings
Chapter 4

6. 1- Alkanes (paraffins) Aliphatic Hydrocarbons
Alkanes –cycloalkanes - Alkene - Alkyne
1- Alkanes (paraffins)
Alkanes have the general formula CnH2n+2 where n = 1,2,3,…
only single covalent bonds
saturated hydrocarbons because they contain the maximum number of hydrogen atoms that can bond with the number of carbon atoms in the molecule
CH4
C2H6
C3H8
methane
ethane
propane
Chapter 4

7. Shapes of Alkanes
“Straight-chain” alkanes have a zig-zag orientation when they are in their most straight orientation.
Straight chain alkanes are also called unbranched alkanes
Chapter 4

8. Branched alkanes have at least one carbon which is attached to more than two other carbons
Chapter 4

9. The first 10 Unbranched Alkanes
Chapter 4

10. Physical Properties of Alkanes and Cycloalkanes
Boiling points of unbranched alkanes increase smoothly with number of carbons
Melting points increase in an alternating pattern according to whether the number of carbon atoms in the chain is even or odd
Chapter 4

11. Nomenclature of Unbranched Alkyl groups
The unbranched alkyl groups are obtained by removing one hydrogen from the alkane and named by replacing the -ane of the corresponding alkane with -yl
Chapter 4

12. Nomenclature of Branched-Chain Alkanes (IUPAC)
Locate the longest continuous chain of carbons; this is the parent chain and determines the parent name.
Number the longest chain beginning with the end of the chain nearer the substituent
Designate the location of the substituent
When two or more substituents are present, give each substituent a number corresponding to its location on the longest chain
Substituents are listed alphabetically
Chapter 4

13. When two or more substituents are identical, use the prefixes di-, tri-, tetra- etc.
Commas are used to separate numbers from each other
The prefixes are used in alphabetical prioritization
When two chains of equal length compete to be parent, choose the chain with the greatest number of substituents
When branching first occurs at an equal distance from either end of the parent chain, choose the name that gives the lower number at the first point of difference
Chapter 4

14. Nomenclature of Branched Alkyl Chains
Two alkyl groups can be derived from propane
Four groups can be derived from the butane isomers
Chapter 4

15. The neopentyl group is a common branched alkyl group
Examples
Chapter 4

16. Classification of Hydrogen Atoms
Hydrogens take their classification from the carbon they are attached to
Chapter 4

17. Constitutional isomers
Constitutional isomers have the same molecular formula but different connectivity of atoms.
have different physical properties (melting point, boiling point, densities etc.).
Physical Contents of the Hexane Isomers
Chapter 4

18. Number of Alkane Isomers
The number of constitutional isomers possible for a given molecular formula increases rapidly with the number of carbons
Number of Alkane Isomers
Chapter 4

19. Isomerism Structural Isomerism Stereo Isomerism 1- Skeletal Isomerism
2- Positional Isomerism
3- Functional Isomerism
4- Tautomeric Isomerism
Stereo Isomerism
1- Geometric Isomerism
2- Conformational Isomerism
3- Optical Isomerism
Chapter 4

20. Structural Isomerism 1- Skeletal Isomerism
Example: Skeletal Isomerism of C6H14
Chapter 4

21. Structural Isomerism 2- Positional Isomerism
Example: Positional Isomerism of C6H14O
Chapter 4

22. Structural Isomerism 3- Functional Isomerism
Example 1: Functional Isomerism of C3H6O
Ketone
Aldehyde
Example 2: Functional Isomerism of C2H6O
alcohol
ether
Chapter 4

23. Structural Isomerism 4- Tautomeric Isomerism
Example: Tutomeric Isomerism of C5H8O2
Chapter 4

24. Synthesis of Alkanes
Hydrogenation of Alkenes and Alkynes
Chapter 4

25. Reduction of Alkyl Halides
Chapter 4

26. Chemical reactions of Alkanes
1- Combustion:
Alkanes react with oxygen.
CO2, H2O, and energy are produced.
Alkane + O CO2 + H2O + heat
CH4 + 2O2 CO2 + 2H2O + energy
Chapter 4

27. Reactions of Alkanes
Free Radicals Halogenation
Chapter 4

28. Mechanisms of Free Radicals Halogenation
Chapter 4