ESTERIFICATION
Introduction:
Esters are a class of organic compounds which, unlike many organics, have
pleasant odors. In fact, many of the "artificial flavors" used in food products are esters very pure esters.
Esters occur naturally but can also be synthesized in the lab. To synthesize an
ester, you must start with two other organic compounds - an alcohol and an acid. The
ester is formed when dehydration occurs. The alcohol and acid react to form the ester and
a water molecule.
..
:O
:O :
C
CH3
..
O
..
H+
C+
H
CH3
H
..
O
..
+
..
:O
H+
..
CH 3CH 2OH
..
H 3C
C
H
H
..
O
..
H+
H
O
.. :
CH 3CH 2O
..
:O
H 3C
C
H
+
..
H
O
..
:O :
+
C
H
O
.. :
H
+O
CH3
O CH 2CH3
H 2O
C
CH3
O CH 2CH3
CH 3CH 2O
Some esters that can be synthesized include methyl salicylate (oil of wintergreen),
isoamyl butyrate (pear), isoamyl acetate (banana), ethyl acetate (fruity), and methyl
acetate (sweet smell).
Purpose:
The purpose of this experiment is to synthesize and identify four esters.
Equipment/Materials:
hot plate (1 or 2 for whole class)
600 mL beaker (1 per hot plate)
Chem Wipes
styrofoam cups (2 per group)
Microscale test tubes (4 per group)
Corks, stoppers or parafilm (4 per group for
microscale test tubes)
concentrated sulfuric acid (4 drops per group)
glacial acetic acid (20 drops per group)
salicylic acid (2 microspatula tips full per
group)
isoamyl alcohol (10 drops per group)
methanol (25 drops per group)
ethanol (20 drops per group plus extra to clean
FTIR platform)
FTIR100 with printer
*Isoamyl Acetate (2-3 drops per group)
*Ethyl Acetate (2-3 drops per group)
*Methyl Salicylate (2-3 drops per group)
*Ethyl Salicylate (2-3 drops per group)
*These standard esters are for FTIR comparison to the student’s prepared esters – do not
need all 4
Safety:
• Always wear safety glasses.
• Keep all reactants away from flames.
•
Never eat or drink in the lab.
Procedure:
1. Using a hot plate, heat water in a 600 mL beaker to approximately 80o C.
2. Label four micro test tubes as “1”, “2”, “3”, and “4”.
3. Place the following in test tube #1:
10 drops of isoamyl alcohol
10 drops of glacial acetic acid
1 drop conc. sulfuric acid
4. Place the following in test tube #2:
10 drops of ethanol
10 drops of glacial acetic acid
1 drop conc. sulfuric acid
5. Place the following in test tube #3:
2 microspatula tips full of salicylic acid
enough methanol to dissolve the acid (add a few drops then shake to
dissolve – repeat – about 25 drops total)
1 drop conc. sulfuric acid
6. Place the following in test tube #4:
2 microspatula tips full of salicylic acid
10 drops of ethanol
1 drop conc. sulfuric acid
7. Place a cork, stopper, or parafilm on each of the 4 test tubes.
8. Pour about 50 mL hot (70-80oC) water in a Styrofoam cup. Place all four test tubes in
the Styrofoam cup water bath and allow them to react for 10-15 minutes. The water
level should cover the contents of the test tubes but not get into the tubes.
Examination:
Note: If doing an FTIR analysis of the esters, perform that analysis BEFORE proceding
with the rest of the lab. FTIR100 analysis directions are found at the end of the
lab.
1. Remove the cap from the test tube and CAUTIOUSLY smell the odor of each.
What do you smell? - record on the data table.
2. Pour the liquid contents of test tube #1 into a clean Styrofoam cup. Swirl the cup one
or two times, then immediately pour the excess reactants into a sink and rinse the cup
with a small amount of water. Smell the inside of the cup. Record what you smell.
3. Repeat examination steps 1 and 2 for the other three esters.
4. Thoroughly wash each of the micro test tubes and cups.
Name _______________________________
Partner’s Name__________________________
Period_______
Date________
ESTERIFICATION
Data Table:
TUBE
SMELL INITIAL
SMELL AFTER RINSING
#1
__________________________
________________________
#2
__________________________
________________________
#3
__________________________
________________________
#4
__________________________
________________________
Questions:
1. Tube 1 contained the following:
___________________smell
or
___________________ester
or
___________________ester
or
___________________ester
or
___________________ester
2. Tube 2 contained the following:
___________________smell
3. Tube 3 contained the following:
___________________smell
4. Tube 4 contained the following:
___________________smell
5. How did the smell of each ester change after rinsing with water?
6. Name the orange-smelling ester formed by adding octanol to acetic acid?
FTIR100 Analysis Directions:
1. Run background
 Clean platform and tip with a few drops of ethanol and a Chem Wipe
 Lower the Cylinder
 Collect
 Background
 Type in “B” then hit green arrow
 Machine runs the scan
 View
 Clear Spectrum

Answer “yes” to the “Save Background” question
2. Place 2-3 drops of ester from test tube #1 on platform
 Lower the Cylinder
 Collect
 Sample
 Type in name of ester
 Run
3. Print IR Spectrum



File – Print
Landscape
OK
4. Raise Cylinder and clean platform and tip with ethanal and a Chem Wipe.
5. Repeat for each of the other 3 esters and the provided standard esters.
6. Clean the platform and tip with ethanol and a Chem Wipe when finished.