Exam 3

1. (15 points) Write complete names for each of the following, including stereochemistry if it is specifically shown.

a)

b)

c)

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2. (15 points) Identify the relationship between the pairs of compounds shown below using the following codes:

a)

b)

c)

d)

e)

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3. (25 points) Complete each of the following reactions by adding the expected major product.
Describe the stereochemistry of the product and describe the mechanism.

a)

b)

c)

d)

e)

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4. (20 points)
(10) Write a complete SN2 mechanism for the reaction of (R)-2-pentanol with HI.
Show all steps and use electron-pushing arrows.

(10) Write a complete SN1 mechanism for the reaction of 2-methyl-2-pentanol with HI.
Show all steps and use electron-pushing arrows.

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5. (25 points) (R)-1,2-Pentanediol reacts with one equivalent of HBr to give a mixture of both (R)- and (S)-2-bromo-1-pentanol.

a) (6) Write out the structures of the reactants and products described.

b) (6) Explain why only one of the two alcohols reacts. Why that one?

c) (6) Assume that pure (R)-2-bromo-1-pentanol has a specific rotation of - 50°.
If the observed product is calculated to have a specific rotation of +10°, what can you conclude about the product mixture:

d) (7) From your conclusion above, explain why that particular enantiomer is favored in the reaction. Clearly show the key step in which the preference is expressed.