JEE Main 202621 JanuaryEvening Shift
- Exam
- JEE Main
- Year
- 2026
- Date
- 21 January
- Shift
- Evening Shift
- Subject
- Chemistry
- Chapter
- Haloalkanes and Haloarenes
JEE Main 2026 · 21 January · Evening Shift · Chemistry · Haloalkanes and Haloarenes
The correct order of reactivity of the following benzyl halides...
The correct order of reactivity of the following benzyl halides towards reaction with KCN is :
Options
- A
- B
- C
- D
Correct answer
B.
Step-by-step solution
Reactivity in SN2 reactions with KCN depends on the stability and nucleophilicity of the transition state.
For benzyl halides, substituents on the benzene ring affect the reactivity of the benzylic carbon through resonance and inductive effects.
Para-nitro group (-NO₂) is strongly electron-withdrawing, activating the benzylic carbon toward nucleophilic substitution.
Para-amino (-NH₂) is electron-donating, deactivating.
Para-hydroxyl (-OH) is weakly donating.
Meta-nitro group has reduced electron-withdrawal compared to para-position.
Order of reactivity based on electronic effects: para-NO₂ (c) > meta-NO₂ (d) > para-OH (a) > para-NH₂ (b).
This gives b > a > d > c
For benzyl halides, substituents on the benzene ring affect the reactivity of the benzylic carbon through resonance and inductive effects.
Para-nitro group (-NO₂) is strongly electron-withdrawing, activating the benzylic carbon toward nucleophilic substitution.
Para-amino (-NH₂) is electron-donating, deactivating.
Para-hydroxyl (-OH) is weakly donating.
Meta-nitro group has reduced electron-withdrawal compared to para-position.
Order of reactivity based on electronic effects: para-NO₂ (c) > meta-NO₂ (d) > para-OH (a) > para-NH₂ (b).
This gives b > a > d > c