Extracting Limonene from Orange Peel

The chemistry lessons which I enjoy the most are those when we do experiments. My favourite experiment that we have done in class was ‘Extracting Limonene from Orange Peel’.

This experiment filled the room with the smell of oranges, creating a better working atmosphere, so all of us really enjoyed doing it. (If you choose A-Level Chemistry you will be able to do this experiment and eat the oranges like we did!). The smell of oranges is caused by the compound limonene. Limonene is a colourless liquid hydrocarbon (and if you’ve done GCSE chemistry you’ll know that a hydrocarbon is made up of only carbon atoms and hydrogen atoms).

For the experiment you will need:

  • Orange
  • Blender
  • Boiling water
  • Bromine water
  • 250cm³ Quickfit round-bottomed flask, stillhead, dropping funnel, Liebig condenser, delivery tube, thermometer pocket
  • Thermometer
  • Boiling tube
  • 100cm³ measuring cylinder
  • Bunsen burners, heat proof mats, tripods and gauze

P.S:Now would be the time to ask if you can eat the oranges!-make sure your hands aren’t contaminated with chemicals.

Now a bit of health and safety:

Organic compounds are highly flammable, irritant, and harmful so be careful when handling them. You must wear eye protection throughout the experiment to ensure that no chemicals get in your eyes. The bromine water is harmful.

If you get chemicals on your skin wash it off immediately.

The method:

  1. You start first by peeling your orange and putting that peel in the blender. This will immediately give of an amazing smell which is the Limonene.
  2. Set up your apparatus for reflux (as seen in figure 1 and the image).
  3. Place the blended orange peel in the 250cm³ boiling flask.
  4. Add 100cm³ of boiling water from a kettle.
  5. Reflux for 30 minutes. This is necessary because reflux is the continual boiling and condensing of a reaction mixture back to the original container to ensure that the reaction takes place without the contents of the flask boiling dry.
  6. Allow it to cool and rearrange the apparatus for distillation (as seen in figure 2).
  7. Collect the Limonene/water distillate in a boiling tube.
  8. Test the distillate for odour.
  9. Add bromine water a drop at a time to a few drops of distillate and analyse the result you get.

I hope you’ve enjoyed the experiment and the oranges!

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