91Ó°ÊÓ

Although p-hydroxybenzoic acid is less acidic than benzoic acid, o-hydroxybenzoic acid is slightly more acidic than benzoic acid. Explain this result.

2-Hydroxybutanedioic acid occurs naturally in apples and other fruits. Rank the labeled protons${\mathbf{H}}_{\mathbf{a}}\mathbf{-}{\mathbf{H}}_{\mathbf{e}}$ in order of increasing acidity and explain in detail the order you chose.

Although it was initially sold as a rat poison, warfarin is an effective anticoagulant used to prevent blood clots. Label the most acidic proton in warfarin, and explain why its ${\mathbf{pK}}_{\mathbf{a}}$is comparable to the ${\mathbf{pK}}_{\mathbf{a}}$of a carboxylic acid.