Hydrocarbons
Objectives:
• Draw and name hydrocarbons as a
prelude to naming other types of
organic compounds; and
• Give some properties and functions
of different hydrocarbons.
Aliphatic vs. Aromatic
Aliphatic
Hydrocarbons
Cyclic
Hydrocarbons
Molecular Representations of Compounds
Alkanes
•
•
•
•
•
described as saturated hydrocarbon
contain the maximum possible number of hydrogens per carbon
Only contains single bond
Formula: CnH2n+2, where n is any integer
Names end with a suffix -ane
Straight-Chain
Alkanes
Branched-Chain
Alkanes
Cyclic
Alkanes
Nomenclature of Alkanes
• In the early nineteenth century, organic compounds were often
named at the whim of their discoverers.
IUPAC Nomenclature
• Systematic names devised by the International Union of
Pure and Applied Chemistry (IUPAC)
Naming Straight-Chain Alkanes
Naming Branched-chain Alkanes
Example:
Example:
1.
2.
Naming Complex Substituents
• Treat the complex substituent as if it is a miniparent with its own
substituents.
• Begin by placing numbers on the substituent, going away from the
parent chain.
• Place parentheses around the name of the substituent.
Common Names
Practice Problems:
c.
a.
b.
Activity 1 (Nomenclature of Alkanes)
1.
c.
b.
2.
Cycloalkanes
• compounds with rings of carbon atoms
• represented by polygons
• general formula (CH2)n, or CnH2n
Naming Cycloalkanes
Practice Problems:
Unsaturated Hydrocarbons
Alkenes
• contains at least one C=C
bond
• general formula of
CnH2n, where n is any
integer
ethene
Alkynes
• contains at least one C C
bond
• general formula of
CnH2n-2, where n is any
integer
ethyne
Naming Straight-Chain Alkenes & Alkynes
Name of Alkene,
Alkyne
ethene, ethyne
propene, propyne
butene, butyne
pentene, pentyne
hexene, hexyne
heptene, heptyne
octene, octyne
nonene, nonyne
decene, decyne
Naming Branched Chain Alkenes &
Alkynes
Naming Cycloalkenes
Practice Problems:
Practice Problems:
Properties of Hydrocarbons
Alkanes
Alkenes
• generally unreactive
• Non-polar
• Insoluble in water,
soluble in most
organic solvents
• Melting point, boiling
point and density
increases as the no.
of carbon atoms
increases.
• reactive than alkanes
• Non-polar
• Insoluble in water,
soluble in most organic
solvents
• Melting point, boiling
point and density
increases as the no. of
carbon atoms
increases.
Alkynes
• more reactive than
alkenes
• Non-polar
• Insoluble in water,
soluble in most
organic solvents
• Melting point, boiling
point and density
increases as the no.
of carbon atoms
increases.
Uses of Alkanes
• First four carbons – used for heating, cooking and electricity
generation
• Carbon Number 5-8 – are volatile liquids, good solvents for
nonpolar substances
• Carbon Number 9-16 – form the major part of diesel and
aviation fuel
• Carbon No. 17 and upwards – components of fuel oil and
lubricating oil also used as anti-corrosive agents, paraffin
wax, used for road surfacing
Uses of Alkenes
Uses of Alkyne
• used as fuel for welding metals (ethyne)
• starting material in the synthesis of polymers