Qu 1 |
Use the following list of compounds to answer the questions
below: |
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Select the compound that is best described as: |
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(a) A neutral, 4 p-electron, anti-aromatic system. |
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(b) A 6 p-electron, aromatic
system. |
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(c) An aromatic system because n=2 in the Huckel 4n+2
rule. |
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(d) A non-aromatic, conjugated 6 p-electron
system |
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(e) A non conjugated hydrocarbon. |
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(f) Non-aromatic as drawn, but if H- were removed would
give an aromatic cation. |
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(g) Non-aromatic as drawn, but has an important resonance
structure that is aromatic. |
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(h) Non-aromatic as drawn but has an aromatic conjugate
base. |
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Qu 2: |
Consider the pKa data for the following
aromatic N containing systems: |
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Henderson-Hasselbach equation:
pKa = pH + log ([A-]/[HA]) |
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Based on the scheme provided, |
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(a) Which species is the strongest acid ? |
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(b) At pH=4.2, what is the relative ratio of pyridine
to its conjugate acid ? |
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(c) Which is the better base: pyridine or aniline,
and why ? |
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(d) Why is pyrrole is a weaker base than pyridine? |
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Qu 3: |
Rate the resonance energies (in comparison to one another)
of each of the following: |
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Qu 4: |
Rate the relative stability of the following carbocations
(in comparison to one another): |
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Qu 5: |
Use the following data to answer the questions below: |
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(a) Calculate the resonance energy of anthracene, |
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(b) Anthracene is known to react with maleic anhydride
in a Diels-Alder reaction. Predict which of the products shown is
obtained. Why ?
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