Applied Science BTEC Nationals/Chemical Laboratory Techniques/Ethyl ethanoate

The experimental details given here are given in good faith and are believed to be safe and workable methods. However, the authors cannot take responsibility for the consequences of performing these experiments.

The experiments are written for experienced science teaching staff to use as instructions for a supervised class of students. The experiments are not designed for students or inexperienced members of the public to perform without supervision. If you wish to attempt the experiments, ensure that you have completed a legally adequate risk assessment beforehand and that you work within the constraints of the risk assessment.

Chemicals and apparatus

 * Quickfit: Round bottom flasks (250 & 100 cm3)
 * Condenser
 * Receiver adapter
 * Tap funnel
 * Stillhead
 * Thermometer pocket
 * Anti-bumping granules
 * Conical flask (50 cm3) & rubber bung
 * Measuring cylinders (10, 100 cm3)
 * Thermometer (110oC)
 * Funnel & fluted paper
 * Heating mantle
 * Sodium carbonate (30% solution)
 * Calcium chloride (granular)
 * Sulphuric acid (conc.)
 * Ethanoic Acid (conc.)
 * Ethanol
 * Ethyl ethanoate (product)

Method
1.	Into one of the round bottom flasks, place ethanol (50 cm3) and glacial ethanoic acid (50 cm3). Add slowly, with cooling and shaking, concentrated sulphuric acid (10 cm3). Ensure that the mixture is homogeneous at each addition. Add some anti-bumping granules and boil the mixture under reflux for about 10 minutes. (See question 1)

2.	Rearrange the apparatus and distil off about two-thirds of the mixture. Transfer the distillate to the separating funnel.

3.	Add sodium carbonate solution (25 cm3) and shake carefully. (see Q 2).

4.	At frequent intervals, invert the funnel and open the tap in order to release the pressure. Allow the liquid to settle and separate the two layers. Discard the aqueous layer (Q3 - make sure you retain the correct layer!).

5.	To the organic layer, in the funnel, add a solution of calcium chloride (25 g anhydrous CaCl2 in 25 cm3 water) and shake vigorously (Q4). Allow the liquid to separate and run off and discard the lower aqueous layer. Run the ethyl ethanoate into a small conical flask and add a few pieces of granular calcium chloride. Allow to stand for approx. 20 minutes., shaking occasionally (Q5).

6.	Filter the liquid through fluted paper into the flask (100 cm3), add a few anti-bumping granules and fit up the apparatus for distillation.

7.	Reject the fraction which distils over in the range 35-40oC (Q6).

8.	Collect the fraction distilling in the range 74 - 79 oC.

9.	Note the appearance and the smell of the final product.

Questions

 * 1) Why boil the mixture and why do this under reflux?
 * 2) State what is observed when the sodium carbonate is added and hence explain why it is used.
 * 3) How did you decide which is the aqueous layer?
 * 4) What is the purpose of the calcium chloride at this stage?
 * 5) What is the purpose of the calcium chloride at this stage?
 * 6) What might distil at this temperature range?
 * 7) Record your yield and calculate your percentage yield.