Which of the following compounds is most acidic?

Question

Quizplus · Accepted Answer

To determine acidity, we look at the stability of the resulting anion after removal of a proton. Based on the electronegativity of the atoms, we can predict the stability of the resulting anion. The more electronegative an atom is, the more stable its anion will be. Therefore, we can compare the acidity of the compounds by looking at the stability of their anions.

I is the most acidic because it has a highly electronegative fluorine atom attached to the carboxylic acid functional group. Fluorine is even more electronegative than oxygen, so the resulting anion will be very stable.

In II and III, the carboxylic acid functional group is attached to a benzene ring, which delocalizes the negative charge and makes the resulting anion less stable than in I.

IV has an alkyl group attached to the carboxylic acid functional group, which decreases acidity by donating electron density and making the anion less stable.

Therefore, the most acidic compound is I.

Which of the Following Compounds Is Most Acidic