Problems Set (Meeting 9)

Announcements

1. The next quiz (= quiz 4) will be administered on February 7, 2008 at 12 pm and will cover most likely the entire Lidocaine project.

2. The final paper will be due on Friday February 15, 2008 at 5 pm in YH 3077E. Late papers will receive 10% off per day late.

3. You should finish the first two steps of the lidocaine project on the first day of the project.

4. 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. A student uses 3M HCl for his reaction. What would he observe?

b. Why is it necessary to have at least three equivalents of stannous chloride in the reaction?

c. The initial reaction affords a white solid. What is this solid and why is it unwise to wash the solid with water after filtration?

d. In the second part of the reaction a solution of the salt from c. is reacted with potassium hydroxide. Which purpose does this serve?

e.Why is it imperative to use a vacuum adapter during the distillation?

f. How does the final product of this reaction look like?

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. Why is glacial acetic acid is used as solvent in this reaction?

b. Why is a-chloroacetyl chloride is used in this reaction instead of a-chloroacetic acid?

c. Why is the amide formed in this reaction only poorly soluble in the solvent?

d. The product has to be dried very rigorously. Explain why.