1. (4 pts) Draw structures corresponding to these names.
a) meta-iodonitrobenzene
b) 3-methyl-2-phenylhexane
2. (15 pts) Consider the reaction below to answer the following questions. (J. Org. Chem. 1992, 57, 625-629)
The rate constant (kobs) for this reaction was measured at different concentrations of NaN3. The results are given in the graph below.
a) (3 pts) What is the mechanistic abbreviation that would be used to describe this reaction?
b) (2 pts) The starting material is chiral. If pure (R)-bromide was used as the starting material, what would be the stereochemical composition expected for the product?
c) (6 pts) Using the curved arrow notation, draw the stepwise mechanism for this reaction that is consistent with the information given.
d) (4 pts) When increasing concentrations of NaBr were added to this reaction, the observed rate of formation of product decreased, as indicated in the Table below. Give a brief explanation for this observation. Hint: look at your mechanism above.
| [NaBr] |
kobs |
|
| 0.00 |
49000 |
|
| 0.05 |
9920 |
|
| 0.50 |
1320 |
|
| 1.00 |
680 |
|
| 3.00 |
230 |
|
| 5.00 |
160 |
3. (5 pts) Consider the reaction below to answer the following questions.
a) (2 pts) What is the mechanistic abbreviation that would be used to describe this reaction?
b) (3 pts) Rate law for this reaction? Rate =
4. (9 pts) Rank the following according to the given criteria by putting the appropriate letters in the boxes provided. (3 pts each; no partial credit)
a) Greatest number of possible E2 products
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> |
> |
b) Rate of SN1 reaction
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b) Rate of formation of elimination products
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5. (4 pts) Rank the compounds below in order of their reactivity to electrophilic aromatic substitution. Label the most reactive "1" and the least reactive "4". Place the numbers in the blanks under the compounds.
6. (9 pts) Circle or fill in the requested information for each of the following structures.
a) Continuous cyclic pi system? Yes / No
# of pi electrons
Circle one: Aromatic / non-aromatic / anti-aromatic
b) Continuous cyclic pi system? Yes / No
# of pi electrons
Circle one: Aromatic / non-aromatic / anti-aromatic
c) Continuous cyclic pi system? Yes / No
# of pi electrons
Circle one: Aromatic / non-aromatic / anti-aromatic
7. (7 pts) Bromination of anisole at the para position produces a carbocation intermediate.
a) (3 pts) In the box above, draw the structure of its intermediate in one of its resonance forms.
b) (4 pts) Briefly describe why the methoxy group directs bromination to the para position (as opposed to the meta position). Use words and drawings.
8. Give the major organic products for each of the following reactions. Indicate stereochemistry for each reaction marked with an asterisk (*). If no reaction is predicted, write NR. (21 pts)
a)
b)*
c)*
d)
e)
f)
9. (6 pts) Give the reagents needed to complete the following conversions.
a)
b)
10. (10 pts) The reactions below fail as written. Indicate why they fail and show the correct set of reactions to completge the conversions.
a)
Correct Reaction Sequence:
b)
Correct Reaction Sequence:
11. (9 pts) Starting with benzene, synthesize the following compound. Show all reagents and all intermediate cmpounds in the synthetic sequence. You may use any organic and inorganic reagents needed.
