Question

Why is benzene extra ordinarily stable though it contains three double bonds?

Answer 1

Answer:

Benzene is extraordinarily stable despite containing three double bonds because it does not behave like a normal polyunsaturated compound. Its stability is explained by the concept of resonance and aromaticity.

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Reasons for the high stability of benzene:

• Resonance:
  In benzene, the six π-electrons are delocalized over the entire ring rather than being confined to three separate double bonds. This delocalization lowers the overall energy of the molecule.
• Aromaticity:
  Benzene satisfies Hückel’s rule, having 6 π-electrons (4n + 2, where n = 1). Aromatic compounds are especially stable due to cyclic delocalization of π-electrons.
• Equal bond lengths: 
  All carbon–carbon bonds in benzene have equal length, intermediate between a single and a double bond. This uniform bonding contributes to its stability.
• Low heat of hydrogenation:
  Benzene releases much less heat during hydrogenation than expected for three isolated double bonds, indicating that it is already in a low-energy, stable state.

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Conclusion:

Thus, benzene is extraordinarily stable because of resonance stabilization and aromatic character, which make its electronic structure more stable than that of ordinary compounds containing multiple double bonds.