1. In an experiment synthesizing an ester, a percentage yield of about 80%
was obtained (given by actual yield divided by theoretical yield times
100). What is the main limitation to the yield (aside from recovery
losses)?
2. What are the advantages of running a reaction under reflux?
3. The following experiment was conducted:
In a round bottom flask taken from a reflux apparatus, 5mL of ethanol,
9mL of butanoic acid and 1mL of concentrated sulfuric acid was mixed
together. This was then heated under reflux for 1hr and cooled to room
temperature. Once cooled, the flask was rinsed with 10mL of cold water
and the mixture was transferred to a separatory funnel where extraction
was performed. The aqueous layer was set aside while to the organic
layer, 5mL of saturated NaCl was added, followed by 5mL of 5%
NaHCO3. The extraction process was repeated once. Once the organic
layer was collected, the crude ester, ethyl butanoate, was transferred to a
small flask and added with approximately 1g of granular anhydrous
Na2SO4 before letting it sit in an ice bath for 10-15 minutes. The ester
was decanted into a vial, leaving behind the solids in the flask. A sample
of the product was then used for boiling point determination.
With this, give what is being asked:
a. How is Le Châtelier's principle applied in this experiment to drive
the formation of the ester?
b. Outline a separation scheme for the isolation of the ester from the
reaction mixture.
