Page 154 - Pharm.Org.Chem I 05-PC101 (1)

STRUCTURE OF BENZENE

• The experimental evidence for the structure of benzene:
1. The molecular formula of benzene is C6H6. therefore it must have

some double, triple and /or rings.
2. It was found to react completely different from olefins.

2025-026 Dr. Marwa El-Wakil 5

• The Kekulé structure suggests alternating double and
single carbon-carbon bonds, and structures I and II are in
rapid equilibrium and couldn’t be isolated.

Now, this postulation was found to be incorrect and no
such equilibrium exists.

• Modern evidence have revealed the actual structure of
benzene as a hybrid of kekule structures I and II.

Resonance Hybrid
representation of

benzene.

2025-026 More stable than other cyclic 6
structures containing double or triple

bond sD r. Marwa El-Wakil

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