Question

Which one is the most acidic compound?

• A.
• B.
• C.
• D.

Answer 1

The Correct Option is D

To determine which compound is the most acidic, we need to consider the structure and stability of the conjugate base formed after the compound donates a proton (H⁺).

1. Conjugate Base Stability: The more stable the conjugate base, the stronger the acid. Stability is often determined by factors such as electronegativity, resonance stabilization, and inductive effect.
2. Electron-Withdrawing Groups: Compounds with electron-withdrawing groups (EWGs) enhance acid strength as they stabilize the negative charge of the conjugate base. These groups pull electron density away, allowing the conjugate base to be more stable.
3. Aryl vs. Alkyl Compounds: Aryl compounds (which have aromatic rings) with EWGs are typically more acidic than their alkyl counterparts. EWGs at key positions on the aromatic ring can significantly enhance acidity through resonance stabilization.

The image options correspond to different chemical structures where the conjugate bases are impacted differently by electron-withdrawing or donating groups. The correct answer is often the compound where the conjugate base can be stabilized through resonance or has strong EWGs attached.

In this case, the correct answer, shown in the image above, is the compound with the strongest electron-withdrawing groups or the one that allows for optimal resonance stabilization of the conjugate base. This makes it the most acidic compound among the options.