Question

Choose the correct statement regarding the $+R$ or $+M$ effect.

• A. Here transfer of $\pi$ (pi) electron takes place from the atom/group towards the conjugated system.
• B. Phenoxide ion does not show $+R$ effect because it has lone pair of electrons.
• C. If a conjugated system has electron withdrawing group attached, then it shows $+R$ effect.
• D. All of the above.

Answer 1

The correct option is A Here transfer of $\pi$ (pi) electron takes place from the atom/group towards the conjugated system.

$+R$ effect :
Here transfer of $\pi$ (pi) electron takes place from the atom/group towards the conjugated system.
In general, the atom or group attached to the conjugated system contains a lone pair/electron pair.
If a conjugated system has electron donating group attached, then it shows $+R$ effect
Groups showing $+R$ effect when attached to conjugated sysytem include :
$-OH,-OR,-N{H}_2,-NHR,-\stackrel{-}{O},-\stackrel{-}{C}{H}_2$

$+R$ effect of phenoxide ion :