The Microscale Preparation of Ethyl Ethanoate

4 Practical 2

The microscale preparation of ethyl ethanoate

Health and safety Ethanol and ethyl ethanoate are both highly flammable, harmful and irritant. Be extra careful when refluxing or distilling not to permit the vapours or the liquid to come into contact with an open flame. Ethyl ethanoate also dissolves polystyrene; therefore, distil into a glass container or fraction collector. During distillation, do not allow the reaction vessel to boil dry: stop the experiment before the vessel reaches one-quarter full. Concentrated sulfuric(VI) acid and glacial ethanoic acid are corrosive. Wear protective gloves when handling these chemicals. Protective goggles must be worn at all times.

Apparatus per student • ethanol • Combo-still • glacial ethanoic acid • distillation column (filled with glass beads) • concentrated sulfuric(VI) acid • refluxing column (filled with glass beads) • silicone oil • microburner • chemical-resistant nitrile gloves • anti-bumping granules • protective goggles • graduated droppers

Procedure

Part I – reflux

1 Add 1.5 cm3 of ethanol (HIGHLY FLAMMABLE, HARMFUL) to the reaction vessel.

2 Add 1.5 cm3 of glacial ethanoic acid (CORROSIVE) to the reaction vessel.

3 Add 2–3 drops of concentrated sulfuric acid (CORROSIVE) to this mixture. Add a few anti-bumping granules. 4 Attach the reaction vessel to the distillation and refluxing head. 5 Three-quarters fill the heating vessel with silicone oil. This should require about 25 cm3. 6 Add a few anti-bumping granules to the heating vessel. 7 Attach the heating vessel to the distillation and refluxing head. The silicone oil level should cover half the reaction vessel. 8 Attach the refluxing column to the distillation and refluxing head. Place the thermometer into the sidearm of the distillation and refluxing head, as shown in the diagram on the next page. 9 Attach this unit to the ring stand, which should be placed into well F1. 10 The microburner should now be placed into well F4, and sit just under the heating vessel.

COAS Chemistry 2 Teacher Resources Original material © Cambridge University Press 2005, 2007, 2009 1 4 Practical 2

Your apparatus should now look like this:

11 Light the burner and gently allow the burner to heat the bottom of the heating vessel. 12 As the silicone oil is heated, you should see the convection currents flow in this vessel. 13 The reaction vessel contents will begin to boil and, as this occurs, remove the direct heat from the reaction vessel by placing the burner into well F5. 14 Reflux for a short period of time (at least 5 minutes).

Part II – distillation 15 Remove the heat source completely and allow the system to cool down. 16 After cooling, remove the reflux column and replace it with the distillation column.

17 You are now ready to distil the product (HIGHLY FLAMMABLE, IRRITANT), which boils at 76.5– 77.5 C. Do not distil the material to a level in the reaction vessel below one-quarter full. (Ethanol boils at 78 C and ethanoic acid boils at 117–118 C. This means that the product has a lower boiling point than either of the reactants. However, due to the closeness of the ethanol boiling point, some of the unreacted ethanol will certainly distil over with the product.)