Question

Question: p-fluoronitrobenzene is more reactive toward hydroxide ion than is p-chloronitrobenzene. What does this tell you about the rate-determining step fornucleophilic aromatic substitution?

Short answer

The rate-determining step in a nucleophilic aromatic substitution reaction is the slow step addition of hydroxide ion. The electronegativity difference between chlorine and fluorine is the reason behind the addition of hydroxide ion to p-Fluoronitrobenzene.

Step-by-step solution

Difference in electronegativity

Among halogen group fluorine is the most electronegative element while compared to chlorine.

Why p-Fluoronitrobenzene is more reactive toward hydroxide ion

Presence of fluorine in p-Fluoronitrobenzene makes it more electronegative substituent than p-chloronitrobenzene. So, three will be a more chance for nucleophilic attack on the fluorine substituted benzene than chlorine substituted benzene.