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. Most of the reactions carried out in the lab use a 1:1: ratio of the reactants. Why is this not a good approach for this reaction?
b. One of the reactants is used in excess here in the reaction. Which one and how much in excess?
c. What is the function of concentrated sulfuric acid in this reaction? Show the appropriate intermediate.
d. After the reaction is terminated, water is added to the chilled mixture. Which purpose does this step serve?
e. Why is the reaction mixture extracted with sodium bicarbonate during the work-up? How does the student know that he extracted often enough? Show pertinent chemical equations.
2. A student refluxes a mixture 1.25 g of malonic acid, 3.00 mL of propanol and six drops of concentrated sulfuric acid for two hours. After the work-up, the student isolated 1.50 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 nD22.5= 1.4200. 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 aniline, anilinium chloride and nitrobenzene.
b. Construct a flow diagram to separate 1,4-dichlorobenzene, 1,2-dichlorobenzene and benzoic acid.