Question

Which of the following shows $-R$-effect?

• A. $-OR$
• B. $-NHCOR$
• C. $-N{H}_2$
• D. $-COOH$

Answer 1

Answer: (D)

The atoms or substituent groups, which represent $+R$ or $-R$ electron displacement effects are as follows :
$+R$-effect: - halogen, - $OH,-OR,-OCOR$, $-N{H}_2,-NHR,-N{R}_2,-NHCOR$.
$-R$-effect; $-COOH,-CHO,>C=O,-CN,-N{O}_2$.
Thus, - COOH is a $-R$-effect showing group, while other options show $+R$-effect.