Diene Stability
Mediumchemistry
Most stable among given dienes is:
Select the correct option:
Solution
Incorrect! Answer:
1,3-Butadiene
- Conjugated Dienes: Dienes where double bonds are separated by exactly one single bond (C=C−C=C).
- Isolated Dienes: Dienes where double bonds are separated by two or more single bonds.
- Stability Cause: In conjugated dienes, there is overlap of p-orbitals across the entire system, allowing π-electron delocalization and resonance.
- Thermodynamics: Heat of hydrogenation shows that conjugated systems (e.g., 1,3-butadiene) are significantly more stable (lower in energy) than isolated or cumulated ones.
- Cumulated Dienes: Dienes like 1,2-butadiene (allenes) where double bonds share a common carbon are the least stable due to inner carbon-carbon strain.
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About This Question
- Subject
- chemistry
- Chapter
- hydrocarbons
- Topic
- diene stability
- Difficulty
- Medium
- Year
- 2025
Solution
Correct Answer:
1,3-Butadiene
- Conjugated Dienes: Dienes where double bonds are separated by exactly one single bond (C=C−C=C).
- Isolated Dienes: Dienes where double bonds are separated by two or more single bonds.
- Stability Cause: In conjugated dienes, there is overlap of p-orbitals across the entire system, allowing π-electron delocalization and resonance.
- Thermodynamics: Heat of hydrogenation shows that conjugated systems (e.g., 1,3-butadiene) are significantly more stable (lower in energy) than isolated or cumulated ones.
- Cumulated Dienes: Dienes like 1,2-butadiene (allenes) where double bonds share a common carbon are the least stable due to inner carbon-carbon strain.
This medium difficulty chemistry question is from the chapter hydrocarbons, covering the topic of diene stability. It appeared in the 2025 exam.
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