1. General

At this point in the quarter, it would be very advisable to review your infrared spectroscopy and NMR spectroscopy notes from lecture. You are expected to have mastered these topics by the time the final exam comes around (in about three weeks). You will need to memorize the most important numbers and trends for the exam because there will be no tables provided!


2. Synthesis of Coumarins

Safety notes:

1. The glassware that is removed from the microwave is very hot. Use a paper towel when removing the Erlenmeyer flask. However, the flask has to be insulated for thirty minutes before working up the reaction mixture.

2.Please note that only the TA is allowed to operate the microwave for safety reasons.

3. When performing the fluorescence test, do not look directly into the UV-lamp because the UV-light will damage your eyes.

Experiment

a. It is very important the reactants and the catalyst are well mixed before placing the mixture in the microwave. A small Erlenmeyer or beaker should be used for the experiment.

b. The reaction mixture has to be well insulated after removing it from the microwave. This will guarantee that the reaction continues afterwards.

c. If the compound does not crystallize upon cooling, the solution can be reheated. A few drops of water are added to the solution (until it is a little cloudy) before the mixture is allowed to cool down.

d. The GC/MS sample (2 mg/mL in ethyl acetate) cannot contain any solids.


3. Photochemical Synthesis of Benzopinacol

Safety notes:

1. Benzophenone is considered a suspected carcinogen by some references.

2. Isopropanol is flammable.

Experiment

a. It is very important that the warm solution is immediately into the reaction vial, which has to be closed immediately (before the solution cools down) and very tightly. Make sure that the cap has the proper seal inside.

b. The label has to be placed on the top of vial. Otherwise, the light will not enter the vial. :-(

c. The instructor will collect the vials at the end of the lab and place them in a window in the 6^th floor. They will be stored there for at least a week.

d. After the return of the vial, the solids are isolated and characterized (probably during meeting 9.

4. Things to think about

a. What would happen if the student would use a large excess of ethyl acetoacetate?

b. Where do you see the advantage of using Amberlyst A15 compared to p-toluenesulfonic acid?

c. What would the student observe in the fluorescence test if the pH-value of the solution was too high (pH>12)?

d. What would change in the fluorescence test if the student uses a shorter wavelength for the excitation?

e. Why does the photochemical reaction not lead to the formation of pinacol?

f. Why is it important that the vial is closed immediately after transferring the solution?

g. Why is glacial acetic acid added in the photochemical experiment?