Question

Which of the following substituents, when present on the benzene ring, exhibit mesomeric effect opposite to that of the remaining three?

• A. $-C{H}_3$
• B. $-Cl$
• C. $-COOH$
• D. $-OH$

Answer 1

Answer: (C)

$-COOH$

$-COOH$ group when present on the benzene ring, exhibits mesomeric effect opposite to that of $-C{H}_3$, $-Cl$ and $-OH$ groups. $-COOH$ group shows -M effect and is meta directing, while $-C{H}_3$, $-Cl$ and $-OH$ groups shows +M effect and are ortho-para directing.