last updated Thursday, April 17, 2003

Problems Set #4

ATTN: answers to the below questions are due at the start of your lab period of Meeting 4; these answers should be part of your pre-lab write-up.

The draft version of paper is due on 4-25-2003 at 5 pm in YH 1217. The draft version is worth 15 points, the final paper 35 points. The draft version should contain the following parts: Abstract, complete introduction, complete discussion of steps 1, 3, 4, and 5, complete experimental part for steps 1,3,4, and 5, spectra discussion for Step 1, 3, 4, and 5,and references. Do not include an essay certain techniques e.g. TLC, GC, NMR etc work. The final paper should not be longer than 15 pages (~1-2 page introduction, 6-7 pages discussion, ~4-5 pages experimental, 3-4 pages spectra section, ~1 page conclusion + references). The draft version should be double spaced with 1'' border for the grading.

1. You are going to use TLC during the epoxidation experiment .

a. Which purpose does this TLC serve in this experiment?

b. You are going to use to different visualization techniques. In which sequence do you use them and why?

b. Which compound do you expect to observe in each technique?

2. What is the source of the oxygen in the formation of the epoxide? Which other oxygen sources could you use with this catalyst?

3. Which information do you get from the [a]_D²⁰ of your ligand?

4. Using Spartan, perform a PM3 calculation for Mn(salen)Cl and SalenH₂. How does the C=N-distance change as you go from SalenH₂ to Mn(salen)Cl? How could you detect the change using spectroscopic techniques available to you?

5. Some of you will use N-pyridine oxide in addition to the catalyst. What is the function of this compound?

6. Why do you use dichloromethane in this reaction?