Question

Correct order of stability is :

• A. $\text{a}>\text{b}>\text{c}>\text{d}$
• B. $\text{d}>\text{c}>\text{b}>\text{a}$
• C. $\text{b}>\text{a}>\text{c}>\text{d}$
• D. $\text{d}>\text{b}>\text{c}>\text{a}$

Hint:

The stability of substituted benzenes follows the general trend: Strong activators $>$ Weak activators $>$ Weak deactivators $>$ Strong deactivators. $\text{NO}_2$ is typically the most destabilizing group.

Answer 1

The Correct Option is B

Stability of substituted benzenes relates to their electronic nature. Generally, electron donating groups ($\text{EDG}$) stabilize the molecule relative to benzene, and electron withdrawing groups ($\text{EWG}$) destabilize it.
(d) $\text{OCH}_3$: Strong $\text{EDG}$ ($+\text{M}$). Most stable. 
(c) $\text{CH}_3$: Weak $\text{EDG}$ ($+\text{H}$). Next most stable. 
(a) $\text{Cl}$: Weak deactivating overall ($-\text{I}>+\text{M}$). Less stable than $\text{c}$. 
(b) $\text{NO}_2$: Strong $\text{EWG}$ ($-\text{M}$). Least stable. 
Standard order of stability based on electronic effects: $\text{d}>\text{c}>\text{a}>\text{b}$.