Chapter 17.5, Problem 2LTS

Interpretation Introduction

Interpretation For the given anionic compound, it should be checked whether the compound is aromatic, nonaromatic or anti aromatic

Concept introduction:

The conditions for aromatic compound are,

1. 1. It should be planar
2. 2. It must obey the Huckel’s rule

   The requirement of an odd number of electron pair is called Huckel’s rule. A     compound can only be aromatic if the number of $\text{π}$ electron in the ring is 2, 6,10,14,18 and so on. This series of number can be expressed mathematically as $\text{4n+2}$, where n should be an integer and the compound is aromatic.

3. 3. Continuous conjugated $\text{π}$ system(all carbon should be in ${\text{sp}}^{\text{2}}$ hybridized state)

   In order to have six $\text{π}$electrons in a seven membered ring one of the carbon atom must possess an empty p orbital. This carbocation exhibits a continuous system of overlapping and p orbitals and has six $\text{π}$ electrons.

   So the first and third criteria for aromaticity are satisfied.

• The conditions for non-aromatic compound is

  The compound not either planar or cyclic but it must satisfy the Huckel’s                         rule

• The conditions for anti-aromatic compound is

  It satisfy all the conditions except Huckel’s rule in the conditions of aromaticity