Resonance Stabilization of Phenoxide Ion

Phenoxide ion (C6H5O-) is the most resonance stabilized among the given ions. Resonance stabilization occurs when electron delocalization is possible through the interaction of p-orbitals. Let's explore the reasons why phenoxide ion is the most resonance stabilized.

Structure of Phenoxide Ion
The phenoxide ion is derived from phenol (C6H5OH) by removing a proton from the hydroxyl group. The resulting ion has a negative charge on the oxygen atom and a lone pair of electrons.

Resonance Structures
Phenoxide ion can be represented by multiple resonance structures due to the delocalization of electrons. Resonance structures are different representations of a molecule or ion that differ only in the placement of electrons.

Resonance Forms of Phenoxide Ion
1. In the first resonance structure, the negative charge is on the oxygen atom, and the lone pair of electrons is on the carbon atom adjacent to the oxygen. This structure is stabilized by the electronegative oxygen atom.

2. In the second resonance structure, the negative charge is on the carbon atom adjacent to the oxygen, and the lone pair of electrons is on the oxygen atom. This structure is stabilized by the delocalization of the negative charge.

3. In the third resonance structure, the negative charge is delocalized over the entire benzene ring, and the lone pair of electrons is on the oxygen atom. This structure is further stabilized by the aromaticity of the benzene ring.

Stability of Phenoxide Ion
The delocalization of the negative charge and the lone pair of electrons in phenoxide ion results in greater stability compared to the other ions. The stability is attributed to the following factors:

1. Aromaticity: The benzene ring in phenoxide ion is aromatic, which provides additional stability to the ion.

2. Delocalization of charge: The negative charge is delocalized over the oxygen atom, adjacent carbon atom, and the benzene ring. This delocalization spreads the charge and stabilizes the ion.

3. Electron-withdrawing effect: The electronegative oxygen atom withdraws electron density from the benzene ring, causing it to become more stable.

4. Conjugation: The conjugation between the oxygen atom, adjacent carbon atom, and the benzene ring allows for the delocalization of electrons, resulting in greater stability.

Overall, the combination of aromaticity, charge delocalization, electron-withdrawing effect, and conjugation makes phenoxide ion the most resonance stabilized among the given ions.