Problems Set (Meeting 9)
Announcements
1. The next quiz (= quiz 3) will be administered on October 22, 2009 at 11 am and will cover the remaining part of the epoxidation project. Make sure that you are in the room by 10:55 am!
2. You should finish the first two steps of the lidocaine project on the first day of the project.
3. The instrumentation room in the first floor (YH 1102) should be left in proper conditions. Lately, there has been an increasing mess i.e. Kim wipes all over the place, unclaimed solutions and glassware, etc. In addition, students do not seem to feel that it is necessary to wear goggles in this room, which is not acceptable either. Please keep in mind that you are still handling chemicals!
Questions:
1. Referring to the conversion of 2,6-dimethylnitrobenzene to 2,6-dimethylaniline (step 1), answer the following questions. Show pertinent chemical equations where appropriate.
a. What is the solvent in this reaction? Rationalize this choice.
b. How many equivalents of SnCl2 are required to perform the reaction? Explain.
c. The initial reaction affords a white solid. In lecture it was emphasized that the solid should not be washed with water. Explain.
d. A student experiences difficulties dissolving his solid in the 30 mL of water. Explain briefly why. How should he proceed?
e. In the second part of the reaction a solution of the salt from d. is reacted with concentrated potassium hydroxide solution. Which purpose does this serve?
f. A student wants to dry his organic layer and decides to use anhydrous sodium sulfate like in many previous experiments. What would he observe?
g. Why is a simple distillation used in this experiment?
h. How do the reactant (2,6-dimethylnitrobenzene) and the product (2,6-dimethylaniline) differ in the FTIR spectrum? Provide exact wavenumbers.
2. Referring to the conversion of 2,6-dimethylaniline to a-chloro-2,6-dimethylacetanilide (step 2), answer the following questions. Show a pertinent chemical equations where appropriate.
a. Glacial acetic acid used as solvent in this reaction. Rationalize this choice.
b. Why does the amide precipitate upon the addition of sodium acetate solution?
c. What are the characteristic changes in the IR spectrum for the product?
d. What is the melting point for the product?