Aromaticity in Heterocyclic Compounds 11.22

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Aromaticity in Heterocyclic Compounds(11.22
11.23)
Can aromaticity affect a cmpds reactivity?
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Examples of Aromatic Heterocylic compounds
Pyridine
Pyrrole
Furan
Thiophene
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Pyridine Molecule
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The Stability of Benzene(11.3 11.4)
What is the empirical evidence for benzenes
unusual stability?
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Derivatives of Benzene and Their Nomenclature
(11.7)
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General Points

• 1) Benzene is considered as the parent andcomes
  last in the name.

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Rules for Naming Benzene Derivatives

• 1) Benzene is last in the name.
• 2) List substituents alphabetically
• Number ring in direction that gives lowest
  locant at first point of difference
• 4) Use the common names for certain derivatives

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Name this compound
Cl
Br
F
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Name this compound
Cl
Br
F
2-bromo-1-chloro-4-fluorobenzene
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Ortho, Meta, and Para
alternative locants for disubstitutedderivatives
of benzene
1,2 ortho(abbreviated o-)
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Examples
NO2
CH2CH3
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The Birch Reduction(11.11)
Only useful synthetic procedure that can reduce
the benzene ring
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Birch Reduction of Benzene
Na, NH3
CH3OH
(80)

• Product is non-conjugated diene.
• Reaction stops here.
• Reaction is not hydrogenation. No H2 involved
• Work thru the mechanism in Carey (Figure 11.8) .