Question
Question: Identify most stable species among given is:...
Identify most stable species among given is:
A
CH3 COO-
B
Cl - CH2 COO-
C
Cl2CHCOO-
D
F - CH2 COO-
Answer
Cl2CHCOO-
Explanation
Solution
The stability of a carboxylate anion is enhanced by electron-withdrawing groups which delocalize the negative charge. Comparing the pKa values: CH3COOH (4.76), ClCH2COOH (2.86), FCH2COOH (2.59), Cl2CHCOOH (1.35). The lowest pKa corresponds to the strongest acid and thus the most stable conjugate base.