Chapter 14, Problem 14.25P

Interpretation Introduction

(a)

Interpretation:

The given compound is to be identified as aromatic, antiaromatic, or nonaromatic.

Concept introduction:

Cyclic compounds with a conjugated $\text{π}$ system can be classified on the basis of Huckel’s rules for aromaticity.

A species that possesses an $\text{π}$ system that is fully conjugated around a ring is aromatic if the number of $\text{π}$-electrons in the cyclic system is $\text{4n+2}$, where $\text{n = 0, 1, 2, }\mathrm{...}$

The species is antiaromatic if the number of $\text{π}$-electrons in the cyclic system is $\text{4n}$, where $\text{n = 0, 1, 2, }\mathrm{...}$

All other species are nonaromatic.

For the $\text{π}$ system of MOs constructed from p orbitals, the ring must be planar.

Interpretation Introduction

(b)

Interpretation:

The given compound is to be identified as aromatic, antiaromatic, or nonaromatic.

Concept introduction:

Cyclic compounds with a conjugated $\text{π}$ system can be classified on the basis of Huckel’s rules for aromaticity.

A species that possesses a $\text{π}$ system that is fully conjugated around a ring is aromatic if the number of $\text{π}$-electrons in the cyclic system is $\text{4n+2}$, where $\text{n = 0, 1, 2, }\mathrm{...}$

The species is antiaromatic if the number of $\text{π}$-electrons in the cyclic system is $\text{4n}$, where $\text{n = 0, 1, 2, }\mathrm{...}$

All other species are nonaromatic.

For the $\text{π}$ system of MOs constructed from p orbitals, the ring must be planar.

Interpretation Introduction

(c)

Interpretation:

The given compound is to be identified as aromatic, antiaromatic or nonaromatic.

Concept introduction:

Cyclic compounds with a conjugated $\text{π}$ system can be classified on the basis of Huckel’s rules for aromaticity.

A species that possesses a $\text{π}$ system that is fully conjugated around a ring is aromatic if the number of $\text{π}$-electrons in the cyclic system is $\text{4n+2}$, where $\text{n = 0, 1, 2, }\mathrm{...}$

The species is antiaromatic if the number of $\text{π}$-electrons in the cyclic system is $\text{4n}$, where $\text{n = 0, 1, 2, }\mathrm{...}$

All other species are nonaromatic.

For the $\text{π}$ system of MOs constructed from p orbitals, the ring must be planar.