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

1. The first quiz will be administered on Tuesday January 17, 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 resolution of 1,2-diaminocyclohexane (step 1), answer the following questions.

a. How are the two enantiomers separated in the lab? Which enantiomer is isolated in the lab and why?

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

c. Assuming 4.8 g of the crude product are isolated, which is still not entirely dry, how much water should be used to recrystallize the crude?

d. What is the theoretical yield (in g based in the quantities given in the reader) for the diammonium salt that you are planning to isolate? Show calculations.

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

a. Dimethylsulfoxide is used as oxidant in this reaction. Which advantages does this method have compared to an oxidation using a PTC and bleach?

b. The reaction should be monitored using TLC. What is the experimenter looking for?

c. The crude product is extracted using hexane. Student did not read the procedure carefully enough and uses dichloromethane instead. What would he observe?

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

3. How does a "chiral auxiliary" work?