Chapter 19.10, Problem 18ATS

Interpretation Introduction

Interpretation:

From the following aromatic compound given, the aromatic rings in the compound have to be ranked in increasing order of reactivity towards electrophilic aromatic substitution reaction.

                                  

Concept Introduction:

• The activation or deactivation of an aromatic ring towards electrophilic substitution reactions depend upon the electronic effects that the substituents produce.

• If the substituents enhance the electron density of the ring then the ring becomes activated towards the electrophilic substitution reactions.

• If the substituents present causes electron drain in the aromatic ring then the ring becomes deactivated towards electrophilic substitution reactions.

• Usually electron donating groups increase the electron density around the aromatic ring and activate the aromatic ring towards electrophilic substitution reactions. Hence they are known as activators.

• Depending upon the strength of activation there are strong, moderate or weak activators.

• Electron withdrawing groups decrease the electron density around the aromatic ring and deactivate the aromatic ring towards electrophilic substitution reactions.  Hence they are known as deactivators.

• Depending upon the strength of deactivation there are strong, moderate or weak deactivators.

• The classification can be summarized as follows –

Activators			Deactivators
Strong	Moderate	Weak	Strong	Moderate	Weak
$\text{-OH}$	$\text{-NHCOR}$	$\text{-R}$	${\text{-NO}}_{\text{2}}$	$\text{-COR}$	$\text{-X}$(HALOGENS)
${\text{-NH}}_2$	$\text{-NROR}$		${\text{-NR}}_{\text{3}}$	$\text{-COH}$
${\text{-O}}^{\text{-}}$	$\text{-OR}$		${\text{-CX}}_{\text{3}}$	$\text{-COOR}$
$\text{-NHR}$	$\text{-O-C=OR}$			$\text{-COOH}$
${\text{-NR}}_{\text{2}}$				${\text{-CONH}}_{\text{2}}$
				${\text{-SO}}_{\text{3}}\text{H}$
				$\text{-CN}$