e. Which has a greater Ka: cyclohexanol or phenol? f. Which is a stronger acid: cyclohexanol or phenol?

Verified step by step guidance

1. Identify the structures: A is phenol and B is cyclohexanol.
2. Recall that the acidity of a compound is related to the stability of its conjugate base.
3. Phenol's conjugate base is stabilized by resonance, as the negative charge can be delocalized over the aromatic ring.
4. Cyclohexanol's conjugate base lacks resonance stabilization, as it is an aliphatic alcohol.
5. Conclude that phenol is a stronger acid than cyclohexanol due to the resonance stabilization of its conjugate base, leading to a greater Ka for phenol.

Key Concepts

Acidity and pKa

Acidity in organic chemistry is often measured by the acid dissociation constant (Ka), which quantifies the strength of an acid in solution. A higher Ka value indicates a stronger acid, meaning it dissociates more completely in water. The pKa, which is the negative logarithm of Ka, is commonly used to compare acid strengths; lower pKa values correspond to stronger acids.

Resonance Stabilization

Resonance stabilization occurs when a molecule can be represented by multiple valid Lewis structures, allowing for the delocalization of electrons. In the case of phenol, the negative charge on the phenoxide ion (the conjugate base) can be delocalized over the aromatic ring, enhancing its stability and making phenol a stronger acid compared to cyclohexanol, which lacks such resonance.

Inductive Effect

The inductive effect refers to the electron-withdrawing or electron-donating effects of substituents in a molecule, which can influence acidity. In phenol, the electronegative oxygen atom can stabilize the negative charge of the phenoxide ion through inductive effects, further contributing to its acidity. In contrast, cyclohexanol does not have such stabilizing effects, making it a weaker acid.