 |
Chapter 11 : Arenes and Aromaticity |  |
|
Chapter 11 : Arenes and Aromaticity | |
Heteroaromatics
Aromatic compounds which contain heteroatoms (e.g. O, N, S) are part of the cyclic conjugated p system and are called heteroaromatics.
The involvement of the heteroatom in the cyclic system requires that
it provides a p-orbital to be part of the conjugated p
system.
This can either be as part of a p
bond in the ring, or a lone pair in a p-orbital to satisfy the criteria
for aromaticity.
This implies that the heteroatom be sp2 hybridised.
Several of the simpler and more common heteroaromatic systems are shown
below.
In each case consider the role of the heteroatom in the p
system.
Is it part of a p bond or does it contribute
a pair of electrons to the p system ?
Position your mouse over the line drawing to check.
|
|
|
|
Resonance Energy |
|
|
 |
|
|
|
|
 |
|
|
|
|
 |
|
|
|
|
 |
|
|
|
|
 |
|
|
|
|
 |
|
|
|
|
 |
|
 |
 |