Chapter 7, Problem 7.55P

Interpretation Introduction

(a)

Interpretation:

The electron-rich sites and electron-poor sites in the given elementary steps are to be identified.

Concept introduction:

An atom with partial or full negative charge is an electron-rich site whereas an atom with partial or full positive charge is an electron-poor site. In an elementary step, electrons tend to flow from an electron-rich site to an electron-poor site.

Interpretation Introduction

(b)

Interpretation:

In each of the given elementary steps, the appropriate curved arrows are to be drawn.

Concept introduction:

A curved arrow can be drawn from an electron-rich site to an electron-poor site to show the flow of electrons from electron-rich site to electron-poor site. The first curved arrow is drawn from the lone pair of negatively charged atom of electron-rich site to the less electronegative atom of electron-poor site. The second curved arrow is drawn from the region between the less electronegative atom and more electronegative atom towards the more electronegative atom indicating the breaking of the bond.

Interpretation Introduction

(c)

Interpretation:

The names of each elementary step are to be identified.

Concept introduction:

The coordination reaction is a Lewis acid-base reaction. A Lewis acid is an electron-pair acceptor, having an atom which lacks an octet. An electron-pair donor is a termed as a Lewis base. In a coordination step, the single curved arrow indicates the flow of electrons from an electron-rich site to an electron-poor site.

The elementary step that occurs with the breaking of a single bond, where both the electrons from that bond end up with one of the atoms initially involved in the bond, is called heterolysis step.

The elementary step in which a species containing a nonpolar $\text{π}$ bond (as part of a double or triple bond) approaches a strongly electron-deficient species is called electrophillic addition reaction.

In electrophilic elimination reaction, the electrophile is eliminated from the carbocation, generating a stable, uncharged, organic species by forming a $\text{C=C}$ bond in case of aromatic species.