Problems Set (Meeting 9)

Announcements

1. The next quiz will be administered on May 2, 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 May 11, 2007 at 5 pm in YH 3077E.

3. You should finish the first two step of the lidocaine project 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.

5. 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 used 3M hydrochloric acid to dissolve stannous chloride. What problem does this pose for the reaction?

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

c. A student obtains a white solid in the reaction. He filters the solid and then washes the preciptate with water. What would he observe?

d. The second part of the reaction concentrated potassium hydroxide solution is used. Which purpose does this serve?

e. Sketch the distillation setup. What is the function of the vacuum adapter in 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. 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. a-chloroacetyl chloride exhibits a peak at n=1811 cm^-1, while a-chloroacetic acid shows one at n=1736 cm^-1. Explain.

d. Why is the amides formed in the reaction only poorly soluble in the solvent?

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