Question

Correct order for nucleophilic addition reaction.

• A. 2 > 1 > 3 > 4
• B. 4 > 3 > 2 > 1
• C. 2 > 3 > 4 > 1
• D. 4 > 2 > 3 > 1

Answer 1

The correct option is C 2 > 3 > 4 > 1

Aldehydes are more reactive towards nucleophilic substitution compared to ketones because of less steric hindrance and electronic factors. In Aldehydes electron withdrawing group increase its reactivity by making the carbonyl carbon more electrophilic.
So (1) is the least reactive since it is a ketone.

Reactivity of carbonyl compounds towards nucleophilic addition reaction depends on the presence of substituted group.
Electron withdrawing showing (-I, -M) effect increases reactivity whereas electron donating groups showing (+R and +I ) effect decreases the reactivity towards towards nucleophilic addition reaction.
As the $-OC{H}_3$ and $-C{H}_3$ groups are electron donating hence the reactivity decreases.
So (2) has the highest reactivity among all.
Between (3) and (4)
$-OC{H}_3$ has a higher $+R$ as the domainating effect whereas in $-C{H}_3$ the effect that dominates is $+H$
Since $+R$ is more stronger and has a higher electron donating nature so, (3) will be more reactive towards nucleophilic reaction than (4)
Thus the correct order is-
2 > 3 > 4 > 1