CHM 412
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
Procedure
|Experiment | |
|1) |Observations: |
|a) Prepare two test tubes containing 0.5 ml of aniline |aniline |
|in each. Then add in 1 ml of distilled water in each of |phenolphthalein: (1 mark) |
|the test tube. | |
| |bromothymol blue: (1 mark) |
|b) Add two drops of phenolphthalein into the first test | |
|tube and 2 drops of bromothymol blue into the second |1-aminobutane |
|test tube. |phenolphthalein: (1 mark) |
| | |
|c) Repeat the test using 1-aminobutane. |bromothymol blue: (1 mark) |
|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 | |
| | |
| |Conclusions/explanations: |
| |aniline |
| |phenolphthalein: (1 mark) |
| | |
| |bromothymol blue: (1 mark) |
| | |
| |1-aminobutane |
| |phenolphthalein: (1 mark) |
| | |
| |bromothymol blue: (1 mark) |
|2) |Observations: |
|a) Add 3 ml of dilute HCl(aq) to 1 ml of phenylamine in |a) 2 marks |
|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) |b) 1 mark |
|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. | |
| |Equations:4 marks (two equations) |
| | |
| | |
| | |
| | |
| | |
| |Conclusion: (1 mark) |
| | |
| | |
| | |
Total: including procedures 20 marks
Procedure
|Experiment | |
|3) |Observation: 2 marks |
|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. | |
| |Equations:4 marks (two equations) |
| | |
| | |
| | |
| | |
| | |
| |Name the products: 2 marks |
| | |
| | |
|4) |Observation: 2 marks |
|a)Dissolve 0.5ml of phenylamine in 0.5 ml of water|Initial stage addition of bromine 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 |Excess addition of bromine water: |
|occur. Explain your observations and write an | |
|equation for the reaction. | |
| | |
| |Equations:2 marks |
| | |
| | |
| |Conclusion: (1 mark)-clue name of the main product |
| | |
| | |
Total: including procedures 17 marks
Procedure
|Experiment | |
| |Observation: 2 marks |
|5) |a) 1 mark |
|a) To 1 ml of phenylamine in a test tube, add 5 ml of | |
|dilute NaOH(aq) and shake the tube vigorously for one |b) 1 mark |
|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. | |
| |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
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