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CHM 412
EXPERIMENT 6
REACTIONS OF AMINES
Objective
To study the reactions of primary amines (1-aminobutane and phenylamine).
Pre lab assignment
1) Write a two paragraphs theory about amines. (4 marks)
2) Draw the general structures for primary, secondary and tertiary amines. (3 marks)
Theory
An amine is a hydrocarbon molecule with nitrogen atom attach to one of the carbon. The lone
pair on the nitrogen atom making an amine as a Lewis base, where the lone pair will be able to
be donate in making a dative bond. Amine is a weak base therefore it able to form salt with
strong acids such as hydrochloric acid. In this section aromatic amine will be used as part of
investigation is phenylamine. The -NH2 attach to the benzene ring making the ring highly
activating and reaction with bromine water will be part of identification for phenylamine.
Chemicals
1-aminobutane (buytlamine),
phenylamine (aniline/aminobenzene),
glacial acetic acid/ethanoic acid,
acetic anhydride/ethanoic acid anhydride,
dilute NaOH(aq),
dilute HCl(aq),
phenolphthalein indicator,
bromothymol blue indicator,
benzoyl chloride.
Apparatus
5-10 test tubes
One 250 ml beaker
Two 100 ml beaker
Blue and red litmus paper
Hot plate
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Procedure
Experiment
1)
a) Prepare two test tubes containing
0.5 ml of aniline in each. Then add in
1 ml of distilled water in each of the
test tube.
b) Add two drops of phenolphthalein
into the first test tube and 2 drops of
bromothymol blue into the second
test tube.
c) Repeat the test using 1aminobutane.
d) Explain your observations based
on the colour change for
bromothymol blue indicator at
different pH as follows:
pH < 6
yellow
pH = 7
green
pH > 7.5 blue
Observations:
aniline
phenolphthalein: (1 mark)
bromothymol blue: (1 mark)
1-aminobutane
phenolphthalein: (1 mark)
bromothymol blue: (1 mark)
Conclusions/explanations:
aniline
phenolphthalein: (1 mark)
bromothymol blue: (1 mark)
1-aminobutane
phenolphthalein: (1 mark)
bromothymol blue: (1 mark)
2)
a) Add 3 ml of dilute HCl(aq) to 1 ml
of phenylamine in a test tube. In
another test tube add in 3ml of
distilled water to 1 ml of
phenylamine
Observe the solubility of
phenylamine in dilute HCl(aq) as
compared to its solubility in water.
b) In the test tube containing HCl(aq)
and phenylamine add in dilute
NaOH(aq) little bit at a time to the
solution in until it is alkaline to red
litmus paper.
Observations:
a) 2 marks
b) 1 mark
Equations:4 marks (two equations)
Conclusion: (1 mark)
Total: including procedures 20 marks
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Procedure
Experiment
3)
a) Dissolve 1 ml of phenylamine
with 3 ml of acetic acid in a dry
test tube. Add 2ml acetic
anhydride and shake the reactant
mixture vigorously.
b) Pour the mixture into 20 ml
ice-cold water in a beaker.
Observation: 2 marks
Equations:4 marks (two equations)
Name the products: 2 marks
4)
a)Dissolve 0.5ml of
phenylamine in 0.5 ml of water
in a test tube. Add 0.5 ml
bromine water and shake the test
tube. Repeat the addition of 0.5
ml of bromine water until there
is a physical change occur.
Explain your observations and
write an equation for the
reaction.
Observation: 2 marks
Initial stage addition of bromine water:
Excess addition of bromine water:
Equations:2 marks
Conclusion: (1 mark)-clue name of the main product
Total: including procedures 17 marks
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Procedure
Experiment
5)
a) To 1 ml of phenylamine in a test
tube, add 5 ml of dilute NaOH(aq) and
shake the tube vigorously for one
minute.
b) Add I ml benzoyl chloride, cover
the mouth of the test tube with a
rubber bung/stopper and shake the
tube vigorously for two minutes. Let
the mixture cool down.
Observation: 2 marks
a) 1 mark
b) 1 mark
Equations:4 marks
Conclusion: (1 mark)-clue name of the main
product
Total: including procedures 9 marks
Question
1.
What make amines weak bases and able to form salts with mineral acids? 2 marks