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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 23, 2007 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 4-27-2007 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.
1. Referring to the epoxidation reaction carried out in the lab, answer the following questions.
a. The reaction is carried out in a two phase system. Explain briefly why and which consequences this has for the setup of the reaction.
b. Why is TLC used in this reaction? What does the experimenter look for?
c. How is the alkene and the epoxide visualized in the TLC experiment? Outline a brief procedure.
d. Why is it important to control the pH-value for the reaction mixture within pH = 9.5-11.5? How is this accomplished in the reaction?
e. Why is hexane added after the reaction is completed?
2. Referring to the catalyst design, answer the following questions.
a. What is the function of the tert.-butyl groups in the catalyst?
b. What is the function of the cyclohexane bridge in the catalyst?
c. What is the advantage of using manganese as active metal center as compared to cobalt?
d. Some students are going to add pyridine N-oxide. What is the purpose of this addition?