Can You Smell That Smell? Synthesis of Esters
There are millions of known organic chemicals, compounds that are composed primarily of carbon,
hydrogen, oxygen, and nitrogen. One way to categorize all these molecules is by identifying various
functional groups within the molecules. You will learn many different functional groups when you
studyorganic chemistry, but for now, below is a list of the most common functional groups.
In this lab, you will be synthesizing three different esters by reacting various alcohols with carboxylic
acids in the presence of a catalyst (sulfuric acid, H2SO4). The reaction follows the general form:
O
O
C
R1
H
O
carboxylic acid
+
O
R
H
alcohol
H2SO4
catalyst
heat
C
R1
ester
R
O
+
H2O
Many esters have characteristic, pleasant smells. The following list contains odors that various esters
possess. You will produce three smells from the list below. Will your nose be able to find the three
smells? Strawberry, apricot, banana, butterscotch, pear, wintergreen, grape, almond, fruity, citrus,
pineapple, apple, marzipan, peach, cinnamon, jasmine, raspberries, and many more!!!!
PROCEDURE
1) Safety equipment must be worn at all times!!! You are using concentrated sulfuric acid. If you get any
on your skin, immediately flush with water. If you spill, sprinkle baking soda over the spill.
2) Fill 250 mL beaker half full with tap water and heat between 60-85 degrees Celsius.
3) Label three test tubes 1-3, or at least keep track of which test tubes you are using.
4) Using the table at end of this procedure, place one mL of appropriate alcohol in each test tube.
5) Place either one mL (acetic acid) or a spatula tip (salicylic acid) in the appropriate test tube as well.
6) Carefully add 3-5 drops of concentrated sulfuric acid (H2SO4) to each of the three tubes.
7) Using a test-tube holder, heat each test tube one at a time in the water bath, for about 5 minutes.
Watch closely to make sure that the tubes don’t boil over!!! After heating place each tube back in test
tube rack.
8) Using your glass stirring rod, pull some of the solution out onto a paper towel. Wave the towel in the
air and/or blow on. Now smell the paper towel and see if you can detect a characteristic smell!
9) Pour all contents of tubes into waste beaker in hood labeled “esters”. Clean tubes and place upside
down in test tube rack for next class. Clean area and dispose of pipettes in wastebasket.
10) Your teacher has two unknown chemicals (A and B) with characteristic smells. Go ask for a smell
and see if you can identify them. A ________________________ B _______________________
Tube #
Carboxylic Acid
Alcohol
(use app. 1 mL)
1
salicylic acid (spatula tip)
methanol
2
acetic acid (1 mL)
n-amyl alcohol
3
acetic acid (1 mL)
octanol
Unknown Ester
(need correct chemical
name in this box)
Unknown Smell
ANALYSIS
Answers to these questions must be typed. Several of the answers require drawing chemical
structures. Leave space on your typewritten document to draw these structures in by hand.
1) (6 pts) For each reaction you did, write out the actual chemical reaction. Be sure to label each
chemical including the new ester you made. You most likely will have to do internet research to get all
the structures correct. See sample here:
O
C
H3C
O
Acetic acid
O
H
+
CH3CH2OH
H2SO4
Ethanol
catalyst
heat
H2
C
C
H3C
O
CH3
+
H2O
Acetic acid ethyl ester
2) (6 pts) Draw the bond dipole arrows for each polar bond contained within the esters you made.
3) (2 pts) Identify the name and structure of unknown compound A. (Internet research needed)
4) (2 pts) Identify the name and structure of unknown compound B. (Internet research needed)
5) (1 pt) Unknowns A and B are not esters. What type of functional group do these unknowns contain?
6) (3 pts) The C=O group is contained within esters, carboxylic acids, and aldehydes. It is known as the
carbonyl group. Chemists often refer to the carbonyl group as an “electron sink” because it tends to
react with atoms that have a  charge. Using what you have learned about polar covalent bonds, can
you draw a picture and explain this reactivity? (Again, you will need to spend some time researching
this on the internet)