Question

The strongest acid among the following compound is:

• A. Acetic acid
• B. Formic acid
• C. 4-chlorobutanoic acid
• D. 2-chlorobutanoic acid

Answer 1

The correct option is D

2-chlorobutanoic acid

Strength of an acids depends on the stability of its conjugate base. Electron donating groups like -CH3 via +I effect, destablizes the conjugate base and makes the acids weaker. On the other hand electron withdrawing groups like -Cl via -I effect, stablizes the conjugate base and makes the acids even ore stronger. Among the given options c and d have electron withdrawing group -Cl and since it is more effective (closer) in 2-chlorobutanoic acid.

Thus, option c is correct.