last updated
Problems Set #5
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.Make sure that you make progress on your formal report as well in terms of literature research and writing the parts that you completed already in the lab. The draft version of paper is due on January 29, 2010 at 4:30 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 in the draft, the more feedback you will get, which will beneficial for the final version. We will try to return the reports by Monday, February 1, 2010.
2. It is highly advisable to look at the reader prior to attending to lecture. There are a lot of issues to discuss in the individual experiments, but not enough time to discuss every little thing in great detail. It is also recommended to review the techniques that should be familiar to you from 30AL/BL i.e. extraction, recrystallization, TLC, IR/NMR spectroscopy, etc.
3. The second quiz will be administered on Wednesday, January 20, 2010 at 11:00 am covering the ligand and catalyst synthesis and characterization. Bring a ruler, non-graphing calculator and blue or black pen with you. Please make sure that you arrive on time (this means that you should be seated by 10:55 am!!!). Late arrivals will not be allowed into the class room since they disturb the rest of the class!! This also means that you will not be allowed to take the quiz!!! The student is only allowed to write in the time slot permitted. This also applies to writing down the name. Failure to do so will be regarded as cheating.
4. There is no data sharing. Everybody has to acquire her/his own spectra and data i.e. malting point, optical rotation. Students who share data will be reported to the Dean of Students since this is be considered cheating.
5. The podcasting problem has finally been solved as well. Apparently, there was some wiring problem. :-( The fourth lecture was recorded and be accessed under bruincast.
And now to the fun part...the prelab questions:
1. Referring to the catalyst design, answer the following questions.
a. What is the exact function of the tert.-butyl groups in the catalyst? What would happen if the were replaced by phenyl groups?
b. What is the function of the cyclohexane part in the catalyst?
c. What is the active species in the epoxidation? Provide a structure for this species.
d. How many products would be obtained if a-methylstyrene was used as reactant for the epoxidation? Explain.
2. Referring to the epoxidation reaction carried out in the lab, answer the following questions.
a. Why is the reaction carried out in a biphasic system?
b. What would happen if the student did not use a buffer in this reaction?
c. A student only isolates 50 mg of the catalyst. Which problem is he facing? How should he proceed?
d.Why is important to work the reaction mixture up immediately after the reaction was completed?
e. The procedure asks to optimize the solvent mixture for TLC. What does this mean and how is this accomplished? Why is this optimization important?
f. The epoxide is visualized using ceric staining. Explain briefly how this method works. Which compounds can be visualized with this technique?