1. Study #2 and #3 in the Alkyl Halide module and #1 in the Ether module in ORGO.

2. This question need not be done for this problem set. It will appear in PS 6. Learn how to determine the Degree of Unsaturation of a compound from its formula. We will be using this concept in class. The text uses a formula. I think the website method is easier. Try this one: C₁₆H₁₂BrCl₂N₃O₂S.

3. Compound A (C₆H₁₄) reacts with chlorine under free radical conditions to form all of its four possible monochloro constitutional isomers (B-E). Compounds B and C are achiral. Compound B does not react readily with methanol but, under the same conditions,compound C reacts readily with methanol to form F, C₇H₁₆O. Monochloro compound D has no diastereomers and is racemic (why?) and compound E is actually a pair of racemic diastereomers E₁ and E₂ (why?). E₁ is of the 2R*,3S* relative configuration (i.e., 2R, 3S and 2S, 3R enantiomers). Assume that E₁ and E₂ are formed in equal amounts. What are the structures of A, B, C, D, E₁ and E₂ and how much of each compound is formed? What is the structure of F and how is it formed?

4. When 1-bromo-2,2-dideuteriocyclohexane is heated in the presence of sodium ethoxide, the major product formed is a cyclohexene. What is its structure and why is it formed?

5. When (2S, 3S)-2-chloro-3-methylheptane (A) is heated in the presence of CH₃ONa/CH₃OH, two alkenes B and C are formed. When the (2S, 3R) diastereomer of A is subjected to the

Paul Walden (1863-1957)

http://www.library.upenn.edu/etext/smith/chemists.html

same reaction conditions, B' and D are formed. What are the structures of B,B',C and D? Is B or C the major product? Is B' or D the major product? How do C and D differ? How do B and B' differ? Illustrate the mechanism for the formation of B,B',C and D.

6. In problem 5, what will be the effect on the ratio B/C if the base is potassium t-butoxide in t-butyl alcohol?. Explain.

7. (3R)-3-Chloro-3-methylhexane reacts with water to form B, C₇H₁₆O. What is the structure of B? How is B formed? Does B display an optical rotation? Explain.

8. One equivalent of cis-1-bromo-4-t-butylcyclohexane and one equivalent of trans-1-bromo-4-t-butylcyclohexane react with one equivalent of potassium t-butoxide. What is the major product of the reaction? Which bromide reacts faster and which bromide will be the major unreacted halide? Explain with illustrations.

9. (R)-2-Bromopropionic acid CH₃CHBrCO₂H) in the presence of aqueous NaHCO₃, gives (R)-lactic acid. How would you explain this result? That is, how would Walden have explained it. [2-Bromopropionic acid is a stronger acid than propionic acid: pKa = 4.87. pK₁ (H₂CO₃): pK₁ = 6.37.]