Week 5 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. Recrystallization
a. Why is 95% ethanol used as solvent in the recrystallization of benzil?
b. Why is it important to bring the solvent to a boil during the recrystallization?
c. How can the crystallization be initiated if no crystals were formed upon cooling?
d. Why are the crystals rinsed with a small amount of ice-cold solvent?
2. Reaction planning of esterification carried out in the lab
a. Which reactant is used in excess here? Why?
b. In which scale is the reaction carried out (# of moles)?
c. Why is sulfuric acid added to the reaction mixture?
d. Why is the reaction mixture refluxed? Which setup is used here?
e. How is the product isolated after running the reaction? Outline a detailed separation scheme.
3. A student refluxes a mixture 5.49 g of anthranilic acid, 10 mL of methanol and 1 mL of concentrated sulfuric acid for two hours. After the work-up, the student isolated 3.9 mL 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 nD23= 1.5840. Which conclusion can he draw from this observation?
d. How does the compound smell?
4. Extraction
a. Construct a flow diagram to separate p-tolualdehyde, benzoic acid and sodium chloride.
b. Construct a flow diagram to separate o-nitrophenol, salicylic acid and methyl benzoate.