Question

For the above three esters, the order of rates of alkaline hydrolysis is

• A. I > II > III
• B. II > III > I
• C. I > III > II
• D. III > I > II

Answer 1

The correct option is C I > III > II

Under alkaline condition, hydroxide attaks on carbonyl carbon of esters to furnish repective acids.
So when the $\delta +$ charge on carbonyl carbon increases, attack of $O{H}^{-}$ becomes more favourable and the rate of hydrolysis increases .
$N{O}_2$ showing strong -I effect will increase the $\delta +$ charge. $OC{H}_3$ shows $+M$ effect and $C{H}_3$ shows $+I$ effect so they diminishes $\delta +$ charge. Since $+M$ is more effective than $+I$, hence rate will be least for compound (II).