lab

Purpose: The purpose of this lab is to remove water from a reaction mixture to form an ester. As water
is removed, the equilibrium is upset. The ester that is being prepared in this experiment is n-propyl
propionate.
Reaction:

Experimental Procedure:
The structural C formulas were written out for the formula of alcohol and the carboxylic acid. Using
densities, the proper amounts of carboxylic acid and alcohol were determined. The proper amounts of
0.974 mL of propanoic acid and 0.823 mL of 1-propanol were determined to be used for the experiment.
The volume of the propanoic acid and 1-propanol were measured and placed into a 5 mL round-
bottomed flask. While swirling, 2 drops of sulfuric acid was added. Then, 3 boiling chips were added for
a heating. A distillation apparatus was set up which involved a distillation column, condenser, and side-
arm. The flask was heated to a gentle boil, then refluxed for 15 minutes.
The round-bottomed flask was raised from reflux to cool after 15 minutes. The apparatus was also
allowed to cool and the apparatus was then tilted allowing the water and other distillate to drain back
into the round-bottomed flask. Due to the density of the water, while the round-bottomed flask was
cooling, the distillate in the side-arm was separated in the water. Before being refluxed again, the
distillate was drained back into the round-bottomed flask, while the water stay in the side-arm. The
round-bottomed flask was lowered back into the sand bath and allowed to reflux for an additional 15
minutes.
After 15 minutes of a second reflux the same cooling and tilting process was performed as in the first
reflux. For a third time, the round-bottomed flask was lowered and allowed to reflux for a final 15
minutes. The apparatus was allowed to cool. This time however, everything in the side-arm, water and
distillate, was drained in the round-bottomed flask. This is because the reaction should have gone to

O

H
O
H+

Propyl Propionate
O

Water

O

OH
Propanoic
Acid

+

OH
1-Propanol

O
O
OHOH

Sulfuric Acid

completion, and water should not have affected the final distillate that was now contained in the round-
bottomed flask.
The ester contained in the round-bottomed flask was carefully pipetted into a centrifuge tube, and 1 mL
of water was added. The mixture in the centrifuge tube was mixed using a pipet for a few minutes. The
aqueous layer was allowed to settle and was carefully removed and placed into a beaker for later
disposal. About 1 mL of sodium bicarbonate was added into the centrifuge tube and the mixture was
mixed again for a few minutes. The reaction mixture was allowed to settle and the aqueous layer was
again carefully removed into a waste beaker for later disposal. For a last time, the extraction was
repeated with about 1 mL of sodium chloride. The reaction mixture was mixed with a pipet for a few
minutes, allowed to settle, and the aqueous layer was carefully removed into a waste beaker for later
disposal. The organic layer that remained in the centrifuge tube was carefully transferred via pipet into
a clean and dry collection vial.
Once transferred, anhydrous spheres of calcium chloride were added to the liquid and swirled. More
spheres were added until the spheres did not clump together anymore which meant that the mixture
had been dehydrated. After, the mixture was allowed to settle for a few minutes with occasional
swirling to make sure that the anhydrous calcium chloride spheres did not clump together.
Using a pipet, the liquid in the collection vial was carefully transferred into a clean and dry tared 5 mL
round-bottomed flask. A small amount of distillate was saved in case a successful distillation could not
be performed. The round-bottomed flask was attached to a distillation column and the lowered into the
sand bath and a distillation was performed. The temperature of the first drop and the collected
distillate was recorded.