Carbonyl Reactivity
Hardchemistry
Relative electrophilicity: acid chloride > aldehyde > ketone > amide because:
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Solution
Incorrect! Answer:
Resonance and −I effects enhance carbonyl electrophilicity in acid chloride
- Definition: Electrophilicity is the 'thirst' of the carbonyl Carbon for electrons. It increases if the carbon has a higher partial positive charge (δ+).
- Acid Chlorides: Chlorine is highly electronegative (−I effect) which pulls density away. While it has lone pairs, its π-donation (resonance) is weak due to poor orbital overlap between 3p (Cl) and 2p (C). Result: Very high δ+.
- Aldehydes vs Ketones: Alkyl groups are electron-donating (+I). Ketones have two such groups, while aldehydes have one. This makes the ketone Carbon less positive and also more sterically hindered.
- Amides: The Nitrogen atom has a lone pair that strongly donates into the carbonyl via resonance (N+=C−O−). This significantly 'fills' the δ+ on Carbon.
- Summary Order: Acid Chloride > Aldehyde > Ketone > Amide.
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About This Question
- Subject
- chemistry
- Chapter
- oxygen organics
- Topic
- carbonyl reactivity
- Difficulty
- Hard
- Year
- 2025
Solution
Correct Answer:
Resonance and −I effects enhance carbonyl electrophilicity in acid chloride
- Definition: Electrophilicity is the 'thirst' of the carbonyl Carbon for electrons. It increases if the carbon has a higher partial positive charge (δ+).
- Acid Chlorides: Chlorine is highly electronegative (−I effect) which pulls density away. While it has lone pairs, its π-donation (resonance) is weak due to poor orbital overlap between 3p (Cl) and 2p (C). Result: Very high δ+.
- Aldehydes vs Ketones: Alkyl groups are electron-donating (+I). Ketones have two such groups, while aldehydes have one. This makes the ketone Carbon less positive and also more sterically hindered.
- Amides: The Nitrogen atom has a lone pair that strongly donates into the carbonyl via resonance (N+=C−O−). This significantly 'fills' the δ+ on Carbon.
- Summary Order: Acid Chloride > Aldehyde > Ketone > Amide.
This hard difficulty chemistry question is from the chapter oxygen organics, covering the topic of carbonyl reactivity. It appeared in the 2025 exam.
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