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 (make sure to read them since you will held responsible to it)

1. The first quiz will be administered in lecture on Monday, January 12, 2009 at 8 am (covering step 2, step 3 and the introduction to asymmetric synthesis). It is the student's responsibility to arrive on time even if the lecture is at 8 am. Late arrivals (even if it is only one minute) will not be allowed to take the quiz, which means that you will receive an automatic zero score for the quiz. If you do not place your name on the quiz to assume authorship, you will receive a zero score as well! You cannot add the name after time was called because this is considered cheating.

2. The draft version of the paper will be due on Thursday, January 29, 2009 at 5 pm.

3. The instructor will not respond to anonymous emails. In other words, if you are not providing your name with the email, you will not get a response.

4. The questions below are due on January 13 or January 14, 2009 depending on when your lab section meets.

Questions

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

a. What is the function of the dimethylsulfoxide in the reaction?

b. How is the temperature controlled during the reaction? Which temperature is desirable here?

c. The reaction is monitored using TLC. Which samples should be spotted here? What is he looking for here?

d. After adding the reaction mixture to water, he extracts the mixture with hexane. The procedure in the Li paper uses dichloromethane. Rationalize the change in solvent .

e. Why is methanol used as solvent for the recrystallization?

f. The carbonyl stretching frequency of the aldehyde is significantly lower than the one in acetaldehyde. Where is it located (±5 cm^-1)? Rationalize this observation (Hint: show an appropriate diagram).

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

a. When the diamine is added to the acid solution, a small amount of precipitate is initially observed that dissolves upon further addition of the diamine. Explain.

b. A student isolates 5.30 g of the crude tartrate salt. How much solvent should he use to recrystallize the crude?

c. After recrystallization, he obtains 1.55 g of the tartrate salt. Determine the percentage yield for this reaction (assume that he used the quantities given in the reader) and comment on it. Show all calculations.

d. The accepted optical rotation value for the product is [a]_D²⁰= +12.5^o. A student observes a specific optical rotation for his sample of [a]= +9.2^o. Determine the optical purity of the sample. Comment on the observed optical purity.