Problems Set - Meeting #4

The second quiz will administered on Thursday, January 20, 2004 at 12 pm in YH4216. Please make sure that you are on time in order to take full advantage of the time allotted for the quiz.

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.

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.

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

a. Why are two equivalents of potassium carbonate used in order to obtain the diamine from the ammonium salt (3) in this reaction?

b. Why is water added to the reaction mixture before it is allowed to cooled to room temperature?

c. Why is it unwise to use the same solution for the optical rotation measurement and the UV-Vis spectrum?

d. Which solvent is used for the UV-Vis spectrum?

e. The ligand exhibit (R,R) geometry. Where does this stereochemistry originate from?

f. Why is a 'rotavap' used during the work-up?

g. The H-NMR spectrum shows a signal at 13 ppm. Assign this signal and rationalize its position.

h. The C=N stretching mode is usually lower in intensity than a C=O mode. Explain.

i. Where does the hydrogen of the imine function appear in the NMR spectrum? How about the carbon atom of the imine function? Rationalize these observations.