Chapter 23, Problem 23.2P

Interpretation Introduction

(a)

Interpretation:

Considering the arenium ion intermediates that are formed in the nitration of fluorobenzene. Using Table 23-1, which one is formed the fastest, which is formed the slowest, which is the most stable and which is the least stable is to be determined.

Concept introduction:

Substituents attached by an atom having at least one lone pair of electrons are ortho/para directors. Substituents attached by an atom having no lone pairs of electrons are: $\text{1}$. Ortho/para directors if they are alkyl groups. $\text{2}$. Meta directors if the substituent contains an electronegative atom at or near the point of attachment. When an ortho/para director is attached to benzene, the ortho and para arenium ion intermediates are lower in energy (more stable) and are formed faster than the meta intermediate. When a meta director is attached to benzene, the meta arenium ion intermediate is lower in energy (more stable) and is formed faster than the ortho or para intermediate.

Interpretation Introduction

(b)

Interpretation:

Considering the arenium ion intermediates that are formed in the nitration of nitrobenzene. Using Table 23-1, which one is formed the fastest, which is formed the slowest, which is the most stable and which is the least stable is to be determined.

Concept introduction:

Substituents attached by an atom having at least one lone pair of electrons are ortho/para directors. Substituents attached by an atom having no lone pairs of electrons are: $\text{1}$. Ortho/para directors if they are alkyl groups. $\text{2}$. Meta directors if the substituent contains an electronegative atom at or near the point of attachment. When an ortho/para director is attached to benzene, the ortho and para arenium ion intermediates are lower in energy (more stable) and are formed faster than the meta intermediate. When a meta director is attached to benzene, the meta arenium ion intermediate is lower in energy (more stable) and is formed faster than the ortho or para intermediate.