Alkenes
Alkenes form part of a Butene isomer
homologous series of
unsaturated hydrocarbons
with the general formula CnH2n
and containing the C=C
functional group. Butene is a straight-chain
unsaturated hydrocarbon
Naming of alkenes while methylpropene is a
branched-chain unsaturated
Names of alkenes usually end hydrocarbon. Butene and
with ‘-ene’. methylpropene have different
Name Ethene Propene Butene melting and boiling points.
n 2 3 4
Molecular C2H4 C3H6 C4H8
Manufacturing
formula
alkenes
Structures of unbranched Alkenes are obtained by
alkenes cracking petroleum (crude
oil). Cracking is the breaking
down of long-chain
hydrocarbons into smaller
molecules. A catalyst may be
Isomers have the same used to speed up the process
molecular formula but known as catalytic cracking.
different structural formula.
, Why is cracking important?
• Cracking is used to produce
In industries, cracking is petrol.
done by passing the • Cracking is used to produce
petroleum fraction short-chain alkenes such as
containing long chains of ethene and propene which are
carbon atoms over a used as starting materials
catalyst at a high for making ethanol and
temperature (about plastics.
600℃). The catalyst is
either aluminium oxide or
silicon (IV) oxide.
• Cracking is used to produce
hydrogen which is a by-
• Cracking converts product.
saturated
hydrocarbons
(alkanes) to
unsaturated
hydrocarbons Chemical properties of alkenes
(alkenes).
• Hydrogen gas may also Alkenes take part in combustion
be produced. This and addition reactions.
hydrogen can be used The functional group of alkenes
to manufacture is the carbon-carbon double
ammonia in the Haber bond.
process.
Alkenes form part of a Butene isomer
homologous series of
unsaturated hydrocarbons
with the general formula CnH2n
and containing the C=C
functional group. Butene is a straight-chain
unsaturated hydrocarbon
Naming of alkenes while methylpropene is a
branched-chain unsaturated
Names of alkenes usually end hydrocarbon. Butene and
with ‘-ene’. methylpropene have different
Name Ethene Propene Butene melting and boiling points.
n 2 3 4
Molecular C2H4 C3H6 C4H8
Manufacturing
formula
alkenes
Structures of unbranched Alkenes are obtained by
alkenes cracking petroleum (crude
oil). Cracking is the breaking
down of long-chain
hydrocarbons into smaller
molecules. A catalyst may be
Isomers have the same used to speed up the process
molecular formula but known as catalytic cracking.
different structural formula.
, Why is cracking important?
• Cracking is used to produce
In industries, cracking is petrol.
done by passing the • Cracking is used to produce
petroleum fraction short-chain alkenes such as
containing long chains of ethene and propene which are
carbon atoms over a used as starting materials
catalyst at a high for making ethanol and
temperature (about plastics.
600℃). The catalyst is
either aluminium oxide or
silicon (IV) oxide.
• Cracking is used to produce
hydrogen which is a by-
• Cracking converts product.
saturated
hydrocarbons
(alkanes) to
unsaturated
hydrocarbons Chemical properties of alkenes
(alkenes).
• Hydrogen gas may also Alkenes take part in combustion
be produced. This and addition reactions.
hydrogen can be used The functional group of alkenes
to manufacture is the carbon-carbon double
ammonia in the Haber bond.
process.
