Functional Groups
 The
bond, atom, or group of atoms which
gives a molecule its specific properties is
called its functional group.
 Eg The functional group of the alkenes is
C = C; the functional group of the
alkanols (alcohol) is – OH.
 Haloalkanes
contain a halogen atom; F, Cl, I
or Br (group 17 elements).
 These group 17 elements have replaced a
hydrogen atom from an alkane
 Haloalkanes are not hydrocarbons
 The functional group is – X, where X is a
halogen.
 The number of the carbon atom to which the
halogen has been bonded must be given
when naming haloalkanes, followed by the
halogen and then the prefix indicating the
number of carbons in the chain.
 The
Alkanols are carbon chains
containing one or more – OH group.
 The – OH group is sometimes called the
‘hydroxy’ group.
 Alkanols have the ending –ol.

Note that each carbon atom has four bonds (valency 4),
each oxygen atom has two bonds (valency 2)
and each hydrogen atom has one bond (valency 1).
Valency is the combining power of an atom.
 Many
alkanols can be oxidised (slowly) by
atmospheric oxygen and (quickly) by
strong laboratory oxidants such as acidified
potassium permanganate (KMnO4) or
acidified potassium dichromate (K2Cr2O7).
 The product of such processes is usually a
carboxylic acid.
 Alkanols also undergo combustion reactions
in air. They can be used as fuels
Propanol (C3H7OH) is
commonly represented
by the molecule
propanol which has the
structural formula
Another isomer of propanol
called propan-2-ol is
commonly represented by the
structural formula where the
single lines between the atoms
represent single covalent
bonds.
 The
carboxylic acids are another
example of a homologous series.
 These compounds contain the functional
group – COOH at the end of the chain.
 When naming a carboxylic acid, add the
ending –oic acid to the alkyl prefix
 These acids have typical acid properties.
 They are classified as weak acids.
 ethanol
+ oxygen
C2H5OH(aq) +O2(g)
ethanoic acid + water.
CH3CO2H(aq) + H2O(l)
 Complete
the revision questions page
183 (29, 30)
 Carboxylic
acids react with alkanols to
form esters.
 Esters are a group of compounds which
give the pleasant ‘fruity’ smell to various
fruits.
 This is called a dehydration or
esterification reaction.
 Concentrated sulfuric acid is used to link
the alkanol and carboxylic acid together
by removing a water molecule.
H2SO4


CH3OH + CH3COOH
methanol + ethanoic acid
CH3COOCH3 + H2O
methyl ethanoate + water
When naming an ester, the
alkanol (alkyl) name is given
first, followed by the acid
part.
The –oic ending of the acid is
replaced with –oate.
 Work
184
through the Sample Problem page
 The
amines have the –NH3 functional
group and are derived from ammonia,
NH3.
 They are named by adding the suffix amine to the alkane group to which the
NH2 has been added
 They are found in many natural and
synthetic drugs. Used in the
manufacture of antibiotics, analgesics
and tranquilisers.
 Alchohol, carboxylic
acids, esters on line
multiple choice
 Complete
the revision questions page
185 (31 – 39)