Week 7 Problem Set 30 BL (Esterification Reaction)
Useful Link: Refractometer
ATTN: answers to the below questions are due at the start of your lab period; these answers should be part of your pre-lab write-up.
1. Reaction planning of esterification carried out in the lab
a. Why is one of the reactants used in excess in this reaction?
b. Which reactant should be used in excess here? Rationalize the choice.
c. What is the function of concentrated sulfuric acid in this reaction? Show the appropriate intermediate.
d. Why is the reaction mixture extracted with sodium bicarbonate during the work-up? How does the student know that he extracted often enough?
e. What is the final purification step for the product? How is it performed correctly?
2. A student refluxes a mixture 1.50 g of p-methoxybenzoic acid, 2.00 mL of isopropanol and 0.5 mL of concentrated sulfuric acid for two hours. After the work-up, the student isolated 1.80 g of the ester.
a. Show a balanced chemical equation for the reaction.
b. Determine the yield of the reaction. Show all calculations.
c. The student observes refractive index of nD21.3= 1.5140. Which conclusion can he draw from this observation?
d. Predict the H-NMR spectrum for the product. Include the multiplicity, the chemical shift and the integration in the table.
3. Extraction
a. Construct a flow diagram to separate n-hexanol, hexanoic acid and sodium chloride.
b. Construct a flow diagram to separate bromobenzene, biphenyl and benzoic acid.