Chapter 14, Problem 14.34P

Interpretation Introduction

Interpretation:

The number of total $\text{π}$ electrons present in the given molecule is to be determined. It is to be determined in how many separate $\text{π}$ systems they reside. The number of electrons in each $\text{π}$ system is to be determined.

Concept introduction:

Each $\text{C=C}$ bond consists of two $\text{π}$ electrons, and each $\text{C}\equiv \text{C}$ consists of four $\text{π}$ electrons. The ${\text{sp}}^{\text{3}}$-hybridized carbon atom isolates one $\text{π}$ system from other. Two double bonds are part of the same $\text{π}$ system if they are separated by exactly one bond, making the double bonds conjugated. The second $\text{π}$ bond of triple bond must belong to a different π system as its p orbitals are perpendicular to the first $\text{π}$ bond of triple bond. A $\text{C=C}$ bond makes a separate $\text{π}$ system if its p orbital is perpendicular to the adjacent $\text{π}$ system.