Experiment 23. The preparation of acetanilide from aniline.
Safety Features:
- 1. Aniline is toxic and can be absorbed through the skin. Use
in a fume hood.
- 2. Concentrated hydrochloric acid can cause severe
burns.
- 3. Acetic anhydride is lachrymatory.
Procedure:
To 60 mL water in a 100 mL Erlenmeyer flask add 2.5 mL
concentrated hydrochloric acid with mixing.
The next step must be done in the fume hood.
Add 2.5 mL aniline (density 1.02 g cm-3) and swirl the mixture.
If the solution is coloured, add a small amount of decolourising
charcoal, swirl the flask for about one minute, and filter off
the carbon.
In a separate container dissolve 4 g sodium acetate
in 10 mL water.
Warm the anilinium chloride solution to 50C on a
water bath and add 3 mL acetic anhydride (density 1.08 g cm-3).
Swirl to effect dissolution and add the aqueous sodium acetate
quickly. Swirl the flask a couple of times and set it in an
ice-bath for 20 min.
Filter, with suction, the crystals of the amide formed and wash
with a small amount of ice-cold water.
Dry the material between filter papers, record the m.p. and submit
your sample for assessment.
Inspect the i.r. spectra of the starting material and product
and record on your worksheet the position of the band which
appears during the acetylation (see Appendix 3).
Relate this to the reaction occurring.
Carry out the nitrous acid test (p 30) on the 1 , 2 and 3
amines (aliphatic and aromatic) provided. Record your results in
tabular form.
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