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Esterification Lab
Introduction
Carboxylic acids and alcohols are often warmed together in the presence of a few drops of
concentrated sulphuric acid in order to observe the smell of the esters formed. You would
normally use small quantities of everything heated in a test tube stood in a hot water bath for a
couple of minutes. Because the reactions are slow and reversible, you don't get a lot of ester
produced in this time. The smell is often masked or distorted by the smell of the carboxylic acid.
A simple way of detecting the smell of the ester is to pour the mixture into some water in a
small beaker. Apart from the very small ones, esters are fairly insoluble in water and tend to
form a thin layer on the surface. Excess acid and alcohol both dissolve and are tucked safely
away under the ester layer.
Small esters like ethyl ethanoate smell like typical organic solvents (ethyl ethanoate is a
common solvent in, for example, glues). As the esters get bigger, the smells tend towards
artificial fruit flavouring - "pear drops", for example.
Safety
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Apparatus and chemicals: Careful this lab includes the use of strong
acids like concentrated sulfuric acid. Everybody has to use lab goggles
and be very careful!!!
Smelling Chemicals: never smell chemicals by sticking your nose into
a test tube.
Esters and their reactants can damage your mucus membrane. Hold
approx 5 inches from your face then fan with a hand over the test
tube opening toward your nose.
Materials:
Each group
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lab apron
eye protection
4 – 25x250mm test tubes
1 – 250ml beaker
2 – 50ml beakers
Hot plate
Thermometer
Ring stand with clamp
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Communal (teacher monitored)
dropper bottles filled with liquid
carboxylic acids and alcohols
Scoopula for solid chemicals
Analytical balance
Name:
Procedure:
1. Set up a 250mL beaker on a hot plate, filling the beaker about 2/3 full
of water.
2. Use a clamp to support a 18x150mm test tube. Lower the test tube
into the water bath.
3. Check the odor of acetic acid and ethanol. WAFT! DON’T SNORT!
4. Put about 2mL of acetic acid into the supported test tube.
5. Add about 2mL of ethanol to the acid in the test tube.
6. Add about 10 drops of concentrated sulphuric acid catalyst to the
mixture. CAUTION!!!-very corrosive!
7. Invert a beaker overtop the test tube.
8. Heat the water bath until the mixture in the test tube starts to bubble slowly. SLOWLY!!!!!
9. Allow the mixture to cool for several minutes.(5minutes)
10. Using a 50mL beaker, fill with 30mL of cold water. Pour test tube contents into this beaker
11. What smell did you get?
12. Repeat procedure 1 through 10 for your choice of making THREE more esters. The final
esters are found below. ONLY ATTEMPT TO CREATE THE LISTED ESTERS. Others can be very
strong. Any solid you are using, use 1.00g of it, other wise 2-3mL of liquid.
13. Dispose your ester down the drain with lots of water, wash with soap and dry.
Results:
1. Complete the table below
Reaction
Alcohol
Acid
1
Ethanol
Acetic Acid
(ethanoic acid)
2
3
4.
Smell before Rx
Smell after Rx
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2. Ester Names and formulas
a. Draw the reactions for 1 - 4 and name the esters you formed.
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Esterification Reactions
Ester
Structure
Smell
Ethyl methanoate
(ethyl formate)
Lemon, rum, strawberry
Methyl ethanoate
(methyl acetate)
glue
isopropyl ethanoate
(isopropyl acetate)
fruity
Benzyl ethanoate
(benzyl acetate)
peaches
Isopentyl ethanoate
(isopentyl acetate or
Isoamyl acetate)
pear, banana (flavoring in Pear drops)
Ethyl ethanoate
polish remover, model glue
octyl ethanoate
fruity-orange
Isobutyl propionate
Rum
Methyl propanoate
fruity
Methyl butanoate
pineapple, apple, strawberry
Ethyl butanoate
banana, pineapple, strawberry
Benzyl butanoate
Fruity, plum
Ethyl pentanoate
apples
Methyl salicylate
(Methyl-2-hydroxybenzoate)
root beer, wintergreen, Germolene
Methyl benzoate
fruity, ylang ylang, feijoa
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Name:
Teacher Copy: Esterification Reactions
Alcohol
ethanol
Carboxylic Acid
methanoic acid
(Formic acid )
Ester
Ethyl methanoate
(ethyl formate)
Structure
Smell
Lemon, rum,
strawberry
methanol
Methyl ethanoate
glue
Isopropyl alcohol
isopropyl
ethanoate
fruity
Benzyl alcohol
Benzyl ethanoate
peaches
Isoamyl alcohol
(Isopentyl alcohol)
ethanoic acid
(Acetic acid)
Isoamyl ethanoate
pear, banana
(flavoring in Pear
drops)
nail polish
remover, model
paint, model
airplane glue
ethanol
Ethyl ethanoate
octanol
Octyl ethanoate
fruity-orange
Isobutyl alcohol
Isobutyl
propionate
Rum
methanol
Methyl propanoate
fruity
methanol
Methyl butanoate
Propanoic acid
ethanol
Benzyl alcohol
STRONG SMELL
Butanoic acid
(butyric acid)
Ethyl butanoate
pineapple, apple,
strawberry
banana, pineapple,
strawberry
Benzyl butanoate
Fruity, plum
apples
Modern root beer,
wintergreen,
Germolene and
Ralgex ointments
(UK)
ethanol
Pentanoic acid
Ethyl pentanoate
methanol
Salicylic acid
(2-hydroxybenzoic
acid)
Methyl salicylate
(Methyl-2hydroxybenzoate)
methanol
Benzoic acid
Methyl benzoate
fruity, ylang ylang,
feijoa
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