ATTN: answers to the below questions are due at the start of your second lab period; these answers should be part of your pre-lab write-up.

Announcements

The first quiz will be administered on Tuesday April 11, 2006 at 12-12:15 pm covering step 2, step 3 and the theoretical aspects of asymmetric synthesis. Please make sure to come on time.

Questions

1. Referring to the oxidation of the benzylic alcohol (step 3), answer the following questions:

a. Why is it very important to choose the oxidant carefully when oxidizing benzylic alcohols? Give two examples for oxidants that would not be suitable here and explain why.

b. Why does the reaction mixture have to be heated to 110 ^oC?

c. Sketch a TLC plate for the incomplete reaction (stationary phase: silica, solvent: dichloromethane:hexane=1:1, lane1: benzylic alcohol, lane 2: aldehyde, lane 3: sample from reaction mixture)

d. Why is it important to dilute the sample from the reaction mixture with dichloromethane prior to applying it to the TLC plate?

e. The crude product is recrystallized from hot methanol. Rationalize this choice. Which precautions should be taken here?

2. Referring to the resolution of 1,2-diaminocyclohexane (step 1), answer the following questions.

a. Why is L(+)-tartaric acid used in the resolution of the diamine?

b. During the course of the reaction a precipitate forms initially which redissolves upon further addition of the diamine. Rationalize this observation.

c. What is the theoretical yield (in g based in the quantities given in the reader) for the diammonium salt? Show calculations.

d. How is the identity and purity establish for the final product in the reaction?