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. Work-up of the reaction mixture
a. Why is the extraction be performed with NaHCO3 and not NaOH solution?
b. Why do you have to be careful in the beginning? Show pertinent equations for the extraction with NaHCO3?
2. Refractive index of isoamyl acetate
a. A student obtains a refractive index of 1.4040 at 24 oC. What would be the refractive index of his compound at 20oC?
b.Based on this data, can he confirm that he successfully isolated the ester? If not, what could the isolated liquid be?
3. A student refluxes a mixture 25.0 g of salicylic acid, 15 mL of propanol and 2 mL of concentrated sulfuric acid for two hours. After the work-up, the student isolated 21 g of the ester.
a. Suggest a procedure to isolate the ester.
b. Determine the yield of the reaction. Show all calculations.
c. How could the student improve the percentage yield of this reaction?
d. What would happen if he runs the reaction without the sulfuric acid?
e. Why is the reaction mixture refluxed?
4. Separation
a. Construct two different flow diagrams to separate an amine, a carboxylic acid and a hydrocarbon.
b. Construct a flow diagram to separate a phenol, a carboxylic acid and a ketone.
c. A slightly polar organic compound distributes between an organic solvent and water with a partition coefficent of (in favor of the organic solvent). What simple method can be used to increase the partition coefficent?
d. When performing extractions in small scale, the number of transfer steps should be minimized. With regard to this, would it be better to use a solvent that is heavier or lighter than water when extracting a compound from an aqueous layer?