Preparing Esters

[laurena grieger]

Does anyone have or use esters in their year 11 experiments? I would appreciate hearing from anyone that make esters and the materials they use, and how they go about it. We currently use a quickfit apparatus with Ethanoic acid and Butanol and are considering a change. Any advice or help would be appreciated on this topic. Kind regards, Laurena.

[ellice]

Hi Laurena,
We did this last term. I gave them ethanol, methanol and butanol as the alcohols, and we had for the organic acids, acetic, formic, salicylic and benzoic. The butanoic (smells like vomit) didn't make an appearance this time!!
You end up with a good range of smells.
Good luck.
Ellice

[Whspa]

This is what we do. It's simple and produces a great range of odours.
MAKING ESTERS:
Put approx 2ml of each substance into a large test tube, add approx 15 drops of sulfuric acid (as a catalyst).
Stopper the test tube loosely with cotton wool.
Place the test tube in a large beaker of boiling water for approx 10-15 minutes.
Pour contents into a 100ml conical flask approx 50ml of water and swirl.
Waft odour.

RESULTS:
a) methanol + propanoic acid => methyl propanoate + water. (nail polish remover)
b) ethanol + propanoic acid => ethyl propanoate + water (rum)
c) propanol + propanoic acid => propyl propanoate + water (sweet fruity, banana)
d) butanol + propanoic acid => butyl propanoate + water (sweet fruity, pineapple)
e) methanol + salicylic acid => methyl salicylate + water (oil of wintergreen)
f) propanol + glacial acetic acid => propyl ethanoate + water (pear)
g) ethanol + butanoic acid => ethyl butanoate + water (pineapple)
h) methanol + butanoic acid => methyl butanoate + water (apple)

[RosalieM]

If you do a search for esters you will find some lists people have written up in the past which tell you what combinations produce which esters. Very helpful. We did it a few weeks ago. I just brought all of the appropriate alcohols/acids out and the kids were allowed to choose their own ester.

[laurena grieger]

Thanks very much for your information, I'm glad that we can help each other out. I have another question and that is: Do you use Quickfit Apparatus? Recently when a year class was making esters, the Bottom of the Pear shape flask, broke an sprayed bench and equipment with Butanol and Ethanoic acid. Bench paint was eaten away by acid. We would like to change this combination and were wondering what other schools use to make there esters. Any help and advice would be helpful.
laurena

[RosalieM]

Yes, we use quickfit, and depending on the class the teacher either has them sit the flask in a waterbath on a gauze mat over the bunsen, or else they have the flask (without the water bath) still resting on a gauze mat. Even though the gauze mat makes it take longer, it saves the flask falling if something goes wrong.

[Xenon]

We use the round quickfit flasks, attach condenser and reflux in an electric heating mantle.

[ellice]

When senior chem do this prac, it's done in test tubes that go in a water bath. We usually set up a dem with the quickfit apparatus.

[smiley]

After an idea from the WA lab techs site, we have purchased individual flavours of Jelly Belly beans and use them to complement this experiment. Either the lesson after or the lesson before making esters, we get the kids to do a blind taste test on the flavours that we created in class. i.e.: Raspberry, orange, banana, green apple, pear (yuck), pineapple

[Whspa]

This might help.

[vlclabbie]

OMG Smiley................. Send me the pear ones!!!!!!!!!!!!!!!!