Chapter 14, Problem 14.18P

Interpretation Introduction

(a)

Interpretation:

Whether the given compound is aromatic, antiaromatic, or nonaromatic is to be determined.

Concept introduction:

The rule for aromaticity applies only if the system is planar, cyclic, and has a continuous overlap of p-orbitals.

As per Huckel’s rules for aromaticity, the molecule must possess a pi system of molecular orbitals constructed from p-orbitals that are fully conjugated around a ring. The number of electrons in the $\text{π}$ system must be $\text{(4n + 2), n = 0, 1, 2, }\mathrm{...}$

If the number of electrons in the $\text{π}$ system is $\text{4n, n = 0, 1, 2, }\mathrm{...}$, the compound is antiaromatic.

All other compounds are nonaromatic.

Interpretation Introduction

(b)

Interpretation:

Whether the given compound is aromatic, antiaromatic, or nonaromatic is to be determined.

Concept introduction:

The rule for aromaticity applies only if the system is planar, cyclic, and has a continuous overlap of p-orbitals.

As per Huckel’s rule for aromaticity, The molecule must possess a pi system of molecular orbitals constructed from p-orbitals that are fully conjugated around a ring. The number of electrons in the $\text{π}$ system must be $\text{(4n + 2), n = 0, 1, 2, }\mathrm{...}$

If the number of electrons in the $\text{π}$ system is $\text{4n, n = 0, 1, 2, }\mathrm{...}$, the compound is antiaromatic.

All other compounds are nonaromatic.

Interpretation Introduction

(c)

Interpretation:

Whether the given compound is aromatic, antiaromatic, or nonaromatic is to be determined.

Concept introduction:

The rule for aromaticity applies only if the system is planar, cyclic, and has a continuous overlap of p-orbitals.

As per Huckel’s rule for aromaticity, the molecule must possess a $\text{π}$ system of molecular orbitals constructed from p-orbitals that are fully conjugated around a ring. The number of electrons in the $\text{π}$ system must be $\text{(4n + 2), n = 0, 1, 2, }\mathrm{...}$

If the number of electrons in the $\text{π}$ system is $\text{4n, n = 0, 1, 2, }\mathrm{...}$, the compound is antiaromatic.

All other compounds are nonaromatic.