aromaticity criteria

Question

A compound is aromatic if it is cyclic, planar, fully conjugated and contains:

RankGuru · Accepted Answer

1. **Hückel's Rule**: For a molecule to be aromatic, it must possess a closed loop of $(4n + 2)$ delocalized $\pi$ electrons, where $n = 0, 1, 2, \dots$
2. **Other Conditions**:
   - **Cyclic**: Ring structure required.
   - **Planar**: $p$-orbitals must be parallel to overlap effectively.
   - **Conjugated**: Every atom in the ring must have a $p$-orbital.
3. **Examples**: Benzene ($n=1, 6\pi$), Naphthalene ($n=2, 10\pi$), Cyclopentadienyl anion ($n=1, 6\pi$).
4. **Warning**: Systems with $4n$ $\pi$ electrons (like cyclobutadiene) are antiaromatic and unstable.

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aromaticity criteria

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