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 Monday, October 8, 2007 at 10 am covering step 2, step 3 and the theoretical aspects of asymmetric synthesis. Bring a ruler, non-graphing calculator and pen with you. Make sure to come on time. Please make sure that you arrive on time. Late arrivals will not be allowed into the class room since they disturb the rest of the class!!

2. I will offer a workshop on Mondays from 5-6 pm. The first workshop will probably be next Monday and cover infrared spectroscopy.

Questions

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

a. What is the advantage of using DMSO as oxidant in this reaction compared to bleach like in the oxidation of benzoin (in Chem 30BL)?

b. The reaction is monitored using TLC. Which solvent is used here? Which compounds should the student spot on the plate?

c. Why is it imperative to control the temperature well during the reaction? How is this accomplished?

d. After the reaction is terminated, the solution is poured into water? Explain briefly why.

e. Why is hexane is used as solvent for extraction in this experiment and not dichloromethane?

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

a. The separation of the different enantiomers is based on the different solubilities of the L-tartrate salts? Why do the two enantiomers exhibit different solubilities in water?

b. In the beginning of the reaction a precipitate is observed that dissolves on further addition of the amine. Explain.

c. What is the maximum yield (in g) based on the amounts and chemicals given in the reader? Show all calculations.

d. The accepted optical rotation value for the product of step 1 is a= +12.5^o. A student observes a specific optical rotation for his sample of a= +11.5^o (corrected for concentration). Detemine the optical purity and rationalize the result. Which impact does this result haves for the project overall?