Saturday, January 26, 2008

IIt JEE Revision Aromaticity Huckel Rule

Aromatic compounds are those which resemble benzene in chemical behaviour.
They contain alternate single and double bonds in a cyclic structure.
They undergo substitution reactions rather than addition reactions

Criteria for Aromaticity- Contribution by Huckel

1. Delocalisation: The molecule should contain a cyclic cloud of delocalized Pi electrons above and below the plane of the molecule.

2. Planarity:For a molecule to be aromatic, the ring must be planar.

3. Huckel Rule: the pi electron cloud must contain a total of 4n+2 pi electrons whre n is an integer equal to 0,1,2,3.

Benzene has 6 pi electrons, napthalene has 10.

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