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Problems Set #7
ATTN: answers to the below questions are due at the start of your lab period of Meeting 7; these answers should be part of your pre-lab write-up.
1. Given is a mixture of benzophenone, benzhydrol and diphenylmethane.
a. Student A runs a TLC (plate:silica, solvent: hexane) for the mixture. How would the TLC plate look like?
b. Student B decides to use a 1:1 mixture of hexane and ethyl acetate. How would his results differ from the one obtained in a.?
c. Student C uses dichloromethane as a solvent. How does the result compare to a. and b.?
2. Why is it necessary to spot the TLC plate relatively heavily when you try to identify the fractions that contain your compound?
3. Why is the Jacobsen ligand brown in color? Explain briefly.
4. Referring to the H-NMR spectrum of b-methylstyrene oxide, answer the following questions.
a. Which splitting pattern would the two protons on the three membered ring exhibit?
b. How could you distinguish between the cis and trans form?
c. What would be the chemical shift (d) for these protons?
5. Given are the following GC and MS data for an epoxidation product. Identify the compound and determine the e.e. value.
MS for peak A and B:
MS spectrum for C:
General
There will be no in-lab quiz during meeting 7. Please make sure that you come very well prepared to the lab in order to finish up the "Epoxidation project" during this week. You will not be allowed to come to the during another lab period to finish the experimental work. Make sure that you submit a NMR sample at the end of the section so that the instrumentation TA can acquire the spectra. If possible, also acquire the GC/MS spectrum this week or during the next meeting.
We will try to return the graded draft versions in lecture on Tuesday. The final paper will be due on October 31, 2003, 5 pm in YH1217. Please make sure that you finish the paper as soon as possible. There is no excuse to turn in the paper late. You had almost six weeks to work on it. The final version has to be submitted in printed form to the instructors office and also be submitted online on turnitin.com at the same time.