OUR LADY OF THE ROSARY COLLEGE CHEMISTRY PRACTICAL MANUAL
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Advanced Level, F.6
Experiment should be carried out under the supervision of a Chemistry teacher
Safety precaution must be noted.
Division of work: individual
AMINES
Introduction
Amines are one of the most important groups of organic nitrogen containing compounds. They
can be regarded as derivatives of ammonia in which one or more of the hydrogen atoms in NH3 is
substituted. We get a compound of the form RNH2, called a primary amine, e.g. CH3CH2NH2,
ethylamine.
Free amines are relatively rare in nature, but they do occur in decomposing protein such as
meat and fish. Normally the –NH2 group is associated with other functional groups and in this respect
it forms an important part of proteins. Compounds containing the –NH2 group are important in the
manufacture of drugs, dyes and nylon.
The intention of this practical is consider the properties of an alkylamine (butylamine) and
arylamine (phenylamine) and to compare their properties with those of ammonia. Butylamine is chosen
because it is a liquid and not too volatile. Phenylamine is also a liquid, colourless when pure, but the
sample you use is likely to be dark-coloured due to atmospheric oxidation.
Caution! Phenylamine is toxic and harmful because of skin absorption. Avoid all skin contact.
Butylamine is an irritant and is extremely flammable. You should manage your apparatus in good
order.
Chemicals
Universal indicator paper, butylamine (or propylamine), phenylamine, ethanoyl chloride,
phenol, 2-naphthol, bromine water, ice, ammonium chloride, sodium nitrate(III) and concentrated
hydrochloric acid, Bench solutions: ammonia, hydrochloric acid, sodium hydroxide and copper(II)
sulphate(VI).
Procedure
Experiment 1
Shake 2 drops of butylamine and 2 drops of phenylamine separately with 2 cm3 of water. Now test
each of these solutions and a solution of ammonia with universal indicator.
Experiment 2
1. Shake 2 drops of butylamine and 2 drops of phenylamine separately with 2 cm3 dilute
2.
3.
hydrochloric acid.
Add dilute sodium hydroxide to the solution of phenylamine in hydrochloric acid until the
mixture is alkaline.
If you carry out this experiment with ammonia, you may have a good contrast.
Experiment 3
1. Add ammonia solution dropwise to 2 cm3 of copper(II) sulphate solution until the ammonia is
present in excess.
2. Repeat the experiment using first butylamine and then phenylamine in place of ammonia solution.
Experiment 4
Ammonia and amines can act as nucleophiles in attacking the positive centres in molecules such
as ethanoyl chloride, CH3COCl and benzoyl chloride, C6H5COCl. For example, ammonia reacts very
vigorously with ethanoyl chloride forming ethanamide.
Caution: Carry out this experiment in a fume-cupboard.
Add 20 drops of benzoyl chloride dropwise to an equal volume (0.7 cm3) of butylamine,
phenylamine and ammonia separately, shaking after the addition of each drop.
Experiment 5
1. Dissolve a full spatula measure of ammonium chloride in 3 cm3 of hot water. Now add an equal
amount of solid sodium nitrate(III).
2. Put 3 drops of butylamine in a test tube and add concentrated hydrochloric acid dropwise until a
clear solution is formed. Dilute the mixture to 3 cm3 with water, add a spatula measure of
sodium nitrate(III) and warm gently.
3. Repeat the experiment using phenylamine in place of butylamine.
Experiment 6
1. Make a solution of 2 drops of phenylamine in 2 cm3 of dilute hydrochloric acid and add it to about
5 cm3 of a crushed ice/water mixture at 5-10 ℃. Add to this mixture a spatula measure of sodium
2.
nitrate(III) and stir well to ensure that the solid dissolves. This solution contains the
benzenediazonium ion, C6H5–N2-.
Dissolve a spatula measure of phenol ( Caution: Avoid skin contact with phenylamine and wear
eye protection) in 2 cm3 of dilute sodium hydroxide solution. Cool this solution to below 5 ℃
and add the diazonium solution drop by drop. Repeat the preparation of an azo dye by using
-naphthol in place of phenol.
Experiment 7
Put 3 drops of phenylamine in a test tube and add concentrated hydrochloric acid drop by drop until the
phenylamine dissolves. Now add bromine water dropwise until no further change occurs.
Data and Results: Record your observations in the following tabular form.
Phenylamine
1(a) Solubility in water
1(b) pH value in water
2.Reaction with aq.HCl
And aq. NaOH
3.Reaction with CuSO4
(a) several drops
(b) excess amount
4.With benzoyl chloride
5.With nitrate(III)
6.Prepare azo salt
7.with bromine water in acid
Butylamine
Ammonia
N.A.
N.A.
N.A.
Analysis
Give equations for all the above reactions. You should give structures for some of the above
experiments.
Questions for discussion
1.
2.
Draw structures for ammonia, butylamine and phenylamine. Three-dimensional representation
should be drawn for the functional group.
Comment the solubility of the amines in water and account for any differences in solubility.
3.
Comment the basic strength of the amines relative to ammonia and account for any differences in
their strength as bases.
4.
5.
6.
7.
8.
Explain the different solubility of phenylamine in water and in dilute hydrochloric acid. [Given
equation if necessary.]
Propose a reaction mechanism for the reaction between benzoyl chloride and butylamine.
Compare and explain the reactivity of ammonia, butylamine and phenylamine towards benzoyl
chloride.
Comment the stability of the three diazonium salts.
Bromine water reacts with phenylamine instead of benzene. Explain.