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 Tuesday, October 6, 2009 at 12 pm (covering the introduction to asymmetric synthesis and the resolution step). It is the student's responsibility to arrive on time which means that you have to be there at 10:55 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 Friday, October 23, 2009 at 5 pm.
3. The instructor will not respond to anonymous emails. In other words, if you are not providing your name (not just some alias!) with the email, you will not get a response.
4. The questions below are due on September 28, 2009 or September 29, 2009 depending on when your lab section meets.
Questions
1. Referring to the resolution of 1,2-diaminocyclohexane (step 1), answer the following questions.
a. Provide a balanced equation for this reaction including the proper stereochemistry.
b. When the diamine is added to the acidic solution, a small amount of precipitate is initially observed that dissolves upon further addition of diamine. Explain briefly and show appropriate chemical equations.
c. A student isolates 5.00 g of the crude tartrate salt. How much solvent should he use to recrystallize the crude? Which solvent is used here?
d. After recrystallization, he obtains 2.50 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.
e. Assuming the specific optical rotation for the pure product is [a]= +12.5o, determine the optical purity of a sample that exhibits a specific optical rotation of [a]= +11.5o. Comment on the observed optical purity.
2. Referring to asymmetric synthesis, answer the following questions.
a. What is the ultimate goal of asymmetric synthesis? How is this accomplished?
b. Why has asymmetric synthesis become a very important field of organic chemistry?
c. In which way do two enantiomers differ from each other? In which way are they identical?
d. The reaction of many aromatic ketones with BINAL affords enantiomeric alcohols with high stereoselectivity. Rationalize this observation.
e. What are the fundamental differences between the Jacobsen epoxidation and the Sharpless epoxidation?