(43.8C-4.43C) Esters

How are esters formed?

an esterification reaction:

an alcohol + a carboxylic acid

What are esters?

volatile compounds with distinctive smells that are used in perfumes + food flavourings

What is the functional group of esters?

O

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— C — O —

How are esters named?

(alcohol prefix)-yl (acid prefix)-anoate

e.g.

methanol + propanoic acid ⇌ methyl propanoate

(and water)

What reactants form ethyl ethanoate?

ethanol + ethanoic acid ⇌ ethyl ethanoate

in the presence of concentrated sulfuric acid catalyst

How are the displayed formulas for the reaction written?

1. make the functional groups face each other.

2. take out water.

3. bind the carbon and the oxygen to create the ester.

How is the displayed formula of an ester turned back to its reactants?

1. Split the ester at the O—C bond.

2. Slot the O and the O—H back in.

Describe the practical to create ethyl ethanoate.

1. To a beaker, add 5 drops each of ethanol and ethanoic acid.

2. Add 2 drops of sulfuric acid catalyst.

3. Heat in a water bath (no Bunsen- ethanol is flammable.)

4. Pour the mixture into a beaker of 10% sodium carbonate solution- neutralises any acidic impurities.

5. Distill it. As esters are immiscible with water, they will float on the surface.

Why could esters be separated through condensation?

They are volatile so will evaporate before the other components.

Therefore, they can be collected.

What kind of reaction are esterifications?

reversible condensation reaction