Which compound has the lowest pKa? A)(CH₃CH₂O₂C)₂CH₂ B)CH₃CH₂O₂CCH₂CHO C)CH₃CH₂COCH₂CHO D)PhCOCH₂COCH₃ E)(NC)₂CH₂

Question

Quizplus · Accepted Answer

The compound with the lowest pKa is the one in which the acidic hydrogen is most easily removed. In this case, the most acidic proton is the one on the hydroxyl group (-OH) of the carboxylic acid. The compound in choice C has a carboxylic acid group attached to an electron-withdrawing group (ether) which makes the carboxylic acid more acidic and easier to deprotonate, therefore it has the lowest pKa.

Which Compound Has the Lowest PKa