Announcements

1. Make sure that you make progress on your formal report as well in terms of literature search and writing the parts that you completed already in the lab. The draft version of paper is due on 4-27-2007 at 5 pm. The draft version is worth 15 points, the final paper 45 points. For more information what the draft is supposed to contain see here. Late submission will receive less credit. The more of your work you submit here, the more feedback you will get, which will beneficial for the final version. We will try to return the reports by Monday.

2. The next quiz will be administered on Monday, April 16, 2007 at 12 pm covering the resolution step and the ligand synthesis. Please make sure that you show up on time.

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

1. Referring to the synthesis and characterization of the Jacobsen catalyst, answer the following questions.

a. Why is it highly advisable to crush up the manganese acetate before adding it to the ligand suspension?

b. Upon addition of Mn(OAc)₂ to the ligand suspension, the color of the reaction mixture already turns brown in some cases. Rationalize this observation.

c. What is the used as chloride source for the reaction? Why is the chloride added?

d. The IR spectrum exhibits a significant shift to lower wavenumbers for the imine function. Rationalize this observation.

e. Why is it not possible to acquire the optical rotation for the catalyst itself?

2. Referring to the use of metals in organic synthesis, answer the following questions.

a. Why are metals like manganese and iron often part of a catalytic cycle involving redox reactions?

b. The tetrachlorides of titanium and zirconium are frequently used as catalyst as well. Give an example and explain which property of these compounds is used in this reaction?

c. Many chromium compounds are used in oxidation reactions. However, industry tries to avoid their use as much as possible. Explain briefly why.