Chapter 11

ALKANES

Alkanes

• Are hydrocarbons that contain only C-C single bonds

• General Formula: CnH2n + 2 for compounds that contain only C and H atoms

Condensed vs Structural Formula

• Condensed Formula: Ex. CH4

• Structural Formula: shows all bonds

• Ex. H |H - C -

H |H

IUPAC Nomenclature

• Rule 1. Choose the longest carbon chain. Designate it as the parent. Branches from parent are considered as substituents.

IUPAC Nomenclature

• Parent Chain:

• 1 C - methane 6 C’s - hexane

• 2 C’s - ethane 7 C’s - heptane

• 3 C’s - propane 8 C’s - octane

• 4 C’s - butane 9 C’s - nonane

• 5 C’s - pentane 10 C’s - decane

IUPAC Nomenclature

• Substituent: (ends in -yl)

• 1 C - methyl 6 C’s - hexyl

• 2 C’s - ethyl 7 C’s - heptyl

• 3 C’s - propyl 8 C’s - octyl

• 4 C’s - butyl 9 C’s - nonyl

• 5 C’s - pentyl 10 C’s - decyl

IUPAC Nomenclature

• Rule 2. Number the carbon in the parent chain starting from the end nearest the substituent.

• In short, substituents must have the lower numbers.

IUPAC Nomenclature

• Rule 3. Designate the location (position) and name of each alkyl group before the name of the parent chain.

• Ex. 2-methylpentane

IUPAC Nomenclature

• Rule 4. List the substituents in alphabetical order

IUPAC Nomenclature

• Use prefixes if there are more than 1 of a particular substituent.

• Mono- (1) Hexa- (6)

• Di- (2) Hepta- (7)

• Tri- (3) Octa- (8)

• Tetra- (4) Nona- (9)

• Penta- (5) Deca- (10)

Haloalkanes and Cycloalkanes

• Nomenclature for haloalkanes: Same as simple alkanes

•

• Nomenclature of cycloalkanes:Same as simple alkanes, however, add

the term “cyclo” before parent name

Chemical Properties

• The greater the number of C atoms, the higher the boiling point.

Reactions

• 1. Combustion:

• Alkane + O2 --> CO2 + H2O + heat