Page 155 - Pharm.Org.Chem-I 02-06-05-101

Requirements for a compound to be aromatic:

1- Should be planar
2- Contains sp2 hybridized carbons
3- Contains continuous resonance
4- Obeys Huckel’s rule

Huckel’s rule for aromatic compounds
Planar monocyclic rings with a continuous system of p orbitals and 4n+2= π electrons

are aromatic

(where n= integer no. 0,1, 2, 3, etc)

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Examples on Hückel’s Rule 4n + 2 = π es

1- Benzene 1- Planar ∴ AROMATIC
2- Naphthalene 2- sp2 hybridized ∴ AROMATIC
3- continuous resonance
4- Obey Huckel’s rule

4n+2 = 6 electrons
4n = 4
n=1

1- Planar
2- sp2 hybridized
3- continuous resonance
4- Obey Huckel’s rule

4n+2 = 10 electrons
4n = 8
n=2

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