Problems Set - Meeting #4

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.

1. Lysine, one of the twenty amino acids, can be found in potatoes, red meats, fish, and dairy products. It is extensively used in the treatment of cold and canker sores. A sample isolated from one of the previously mentioned source exhibits an optical rotation of a=+1.10^o for a 10% solution in 8M HCl in a 5 cm cell (Assume that the pure compound shows an [a]=+22.5^o).

a.Determine the optical purity of the sample and the absolute stereochemistry of the lysine.

b. Would the optical rotation change if solvent would be changed?

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

a. Potassium carbonate used in the initial stages of the reaction. Show a balanced equation and explain.

b. Why is water added to the solution before the solution is allowed to cool down after the reaction?

c. A student has to acquire the UV-Vis spectrum for the ligand. Which range should he measure? Which concentration is appropriate here?

d. The same students wants to determine the optical purity for the isolated ligand. How can he do it in the Chem 30CL lab?

e. The stretching mode for the OH group is significantly shifted for the ligand. Rationalize this observation.

f. The Mn-N and Mn-O stretching mode are located around 550 cm^-1. How can this be explained?