Problems Set (Meeting 9)

Announcements

1. The next quiz (= quiz 4) will be administered on October 31, 2007 at 10 am and will cover most likely the entire Lidocaine project. It is highly recommended to put some serious study time into this one.

2. The final paper will be due on Friday November 9, 2007 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. Why is it important to use concentrated hydrochloric acid for the reaction? What is the concentration of conc. HCl?

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 how is it separated from the solution?

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. Sketch and label the distillation setup used. Why is a distillation used instead of just boiling off the solvent?

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 (hint: what is glacial acetic acid?)?

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. Why should the supply bottle of a-chloroacetyl chloride be kept closed as much as possible?

e. In which does the IR spectrum of the amide differ from the IR spectrum if the acyl chloride?