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. The alcohol is used in excess in this reaction. Explain briefly why and how much is appropriate here?
b. Why is concentrated sulfuric acid added to the reaction mixture? Show the appropriate intermediate. How much should be used?
c. Why is the reaction mixture refluxed for 60 minutes?
d. Why is the reaction mixture extracted with sodium bicarbonate during the work-up? Show pertinent chemical equations. ?How does the student know that he is done with this step?
e. Why is the crude product distilled in vacuo?
2. A student refluxes a mixture of 3.04 g of m-methoxybenzoic acid, 8.50 mL of iso-propanol and 1.00 mL of concentrated sulfuric acid for two hours. After the work-up, the student isolated 3.70 g of the ester.
a. Show a balanced chemical equation for the reaction.
b. Determine the yield of the reaction. Show all calculations.
c. Predict the boiling point of the product at ambient pressure.
d. The student observes refractive index of nD23= 1.5021. Which conclusion can he draw from this observation?
e. Predict the 1H-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 melamine, benzoic acid and naphthalene.
b. Construct a flow diagram to separate isoamyl alcohol, isopentyl acetate and acetic acid.