Aromaticity and Huckel's Rule
In 1931, Erich Hückel based on molecuar orbital calculation gave a basic rule governing the aromaticity. According to Huckel's rule any fully conjugated monocyclic planar polyene that have (4n + 2)ℼ electrons are aromatic. Here n is an integer (n = 0,1,2,3,4,5...).
For example, Benzene has 6π electrons and it satisfies the Hückel’s rule since the 'n' is one in this case.
Number of ℼ-electrons = 4 x 1 + 2 = 6.
Compounds having benzene ring is called benzenoid aromatic and the compound other than benzene or its derivatives are called non-benzenoid aromatic.
For example, Benzene has 6π electrons and it satisfies the Hückel’s rule since the 'n' is one in this case.
Number of ℼ-electrons = 4 x 1 + 2 = 6.
Compounds having benzene ring is called benzenoid aromatic and the compound other than benzene or its derivatives are called non-benzenoid aromatic.