diene stability

Question

Most stable among given dienes is:

RankGuru · Accepted Answer

1. **Conjugated Dienes**: Dienes where double bonds are separated by exactly one single bond ($C=C-C=C$).
2. **Isolated Dienes**: Dienes where double bonds are separated by two or more single bonds.
3. **Stability Cause**: In **conjugated dienes**, there is overlap of $p$-orbitals across the entire system, allowing $\pi$-electron delocalization and resonance.
4. **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.
5. **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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diene stability

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