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Problems Set #6
ATTN: answers to the below questions are due at the start of your lab period of Meeting 6; these answers should be part of your pre-lab write-up.
Announcements:
1. The next quiz will be on April 25, 2006 at 12 pm. The material covered will include the catalyst synthesis, the epoxidation and the theoretical aspects.
2. The draft version of paper is due on 4-28-2006 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.
1. Referring to the epoxidation reaction carried out in the lab, answer the following questions.
a. What is the function of the bleach in this reaction?
b. How can the reaction time be optimized?
c. Why is hexane added during the work-up? Could one use heptane instead?
d. How is the alkene and the epoxide visualized in the TLC experiment? Outline a brief procedure.
2. A student uses 1.0 g of an unknown alkene (MW=104 g/mol) for the epoxidation. The procedure requires the use of 7 mole% of the Jacobsen catalyst, 10 mole% of the promoter and 1.25 equivalents of bleach. Show all your work.
a. How many grams of the catalyst and the promoter are needed in the reaction?
b. What is the volume of bleach required in this experiment?
c. A fellow student decides to use hexane as a solvent here. What are the consequences?
3. Most of the alkenes used in the lab afford e.e.-values around 50%. Rationalize this observation.