- Basic aromatic ring
Basic aromatic rings are aromatic rings in which the
lone pairof electrons of a ring- nitrogen atomis not part of the aromaticsystem and extends in the plane of the ring. This lone pair is responsible for the basicity of these nitrogenous bases, similar to the nitrogen atom in amines. In these compounds the nitrogen atom is not connected to a hydrogenatom. Basic aromatic compounds get protonated and form aromatic cations (e.g. pyridinium) under acidic conditions. Typical examples of basic aromatic rings are pyridineor quinoline. Several rings contain basic as well as non-basic nitrogen atoms, e.g. imidazoleand purine.
In non-basic aromatic rings the
lone pairof electrons of the nitrogen atom is delocalized and contributes to the aromatic pi electronsystem. In these compounds the nitrogen atom is connected to a hydrogenatom. Examples of non-basic nitrogen-containing aromatic rings are pyrroleand indole.
The basic aromatic rings
purines and pyrimidines are the nucleobasesfound in DNAand RNA.
Simple aromatic ring
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