Reactivity Of Halogens
The order of reactivity of halides in nucleophilic substitution is:
Select the correct option:
Solution
R-I > R-Br > R-Cl > R-F
The reactivity of alkyl halides toward nucleophilic substitution (SN1 or SN2) is determined by the Bond Dissociation Enthalpy of the C−X bond.
- As the halogen increases in size (F→Cl→Br→I), the C−X bond becomes longer and weaker.
- Bond Strength: C−F>C−Cl>C−Br>C−I
- Because the C−I bond is the easiest to break, alkyl iodides release the leaving group most readily, making them the most reactive.
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About This Question
- Subject
- chemistry
- Chapter
- organic compounds containing halogens
- Topic
- reactivity of halogens
- Difficulty
- Easy
- Year
- 2025
Solution
Correct Answer:
R-I > R-Br > R-Cl > R-F
The reactivity of alkyl halides toward nucleophilic substitution (SN1 or SN2) is determined by the Bond Dissociation Enthalpy of the C−X bond.
- As the halogen increases in size (F→Cl→Br→I), the C−X bond becomes longer and weaker.
- Bond Strength: C−F>C−Cl>C−Br>C−I
- Because the C−I bond is the easiest to break, alkyl iodides release the leaving group most readily, making them the most reactive.
This easy difficulty chemistry question is from the chapter organic compounds containing halogens, covering the topic of reactivity of halogens. It appeared in the 2025 exam.
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