The pKa of ascorbic acid (vitamin C, page 2) is 4.17, showing that it is slightly more acidic than acetic acid (CH3COOH,pKa 4.74).
(a) Show the four different conjugate bases that would be formed by deprotonation of the four different OH groups in ascorbic acid.
(b) Compare the stabilities of these four conjugate bases, and predict which OH group of ascorbic acid is the most acidic.
(c) Compare the most stable conjugate base of ascorbic acid with the conjugate base of acetic acid, and suggest why these two compounds have similar acidities, even though ascorbic acid lacks the carboxylic acid (COOH) group.
The pKa of ascorbic acid is 4.17 and pKa of acetic acid is (CH3COOH) 4.7
Ascorbic acid is more acidic than acetic acid.
The structure of ascorbic acid is,
Four different conjugate base of ascorbic acid that formed by deprotonation of the four different OH groups :-