Problems Set (Meeting 9)

Announcements

1. The next quiz will be administered on February 8, 2007 at 12 am and will cover step 1 and step 2 of the Lidocaine project.

2. The final paper will be due on Friday February 16, 2007 at 5 pm in YH3077E.

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

4. Please make sure to return the equipment that you checked out from lab support on time. The later sections often run into problems because the early sections (on Tuesday/Thursday) do not return the equipment.

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. Why is the reaction carried out in a strongly acidic medium? How is this accomplished?

b. How many electrons are transferred during the reaction? Show a balanced chemical equation.

c. In the second part of the reaction, the salt form in the first part of the reaction is reacted with potassium hydroxide solution. Explain briefly why.

d. Diethyl ether is removed by distillation here instead of just boiling it off. Explain briefly why.

e. Sketch the distillation setup. Why is it important to include a vacuum adapter into the setup?

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 is used in this reaction. Rationalize this choice.

b. a-chlorocetyl chloride is used in this reaction as well. Which advantage does this reagent have compared to a-chloroacetic acid?

c. Why is a sodium acetate solution added to the reaction mixture?

d. Why do amides have a lower carbonyl stretching frequency than esters?