Question

What is the order of increasing nucleophilic addition reactivity- $ C{H_3}COC{H_3},{C_6}{H_5}COC{H_3},C{H_3}CHO $ ?

Answer 1

Hint: Nucleophilic addition means the addition of one nucleophile to unsaturated compounds. Aldehydes are more reactive than ketones as aldehydes have less positive inductive effect compared to ketones. Phenyl methyl ketone has a phenyl group which is an electron withdrawing group that has the least reactivity towards nucleophilic addition reactivity.

Complete Step By Step Answer:
Unsaturated compounds means the compounds containing double and triple bonds. Alkenes and alkynes are the examples of double bonded and triple bonded compounds.
Nucleophilic addition means the addition of a molecule consisting of an electrophilic and nucleophilic part. The addition of nucleophile to the double bonded compounds leads to the brokerage of the pi-bond and results in the nucleophilic addition product.
Aldehydes are more reactive than the ketones, as in aldehydes there is only one methyl group and has a smaller inductive effect. Thus, acetaldehyde $ \left( {C{H_3}CHO} \right) $ is more reactive in the nucleophilic addition.
Acetone is a ketone consisting of the molecular formula of $ \left( {C{H_3}COC{H_3}} \right) $ and has more inductive effects than acetaldehyde. Thus, acetone is less reactive than the aldehyde due to a more positive inductive effect.
Methyl phenyl ketone is a ketone consisting of $ \left( {{C_6}{H_5}COC{H_3}} \right) $ and has steric hindrance due to the presence of phenyl group. Thus, it is less reactive than acetaldehyde and acetone.
The increasing order of nucleophilic addition is $ {C_6}{H_5}COC{H_3} < C{H_3}COC{H_3} < C{H_3}CHO $ .

Note:
In methyl phenyl ketone, phenyl is a bulky group and has steric hindrance. Thus, it will not allow the nucleophile to react with it. leads to the least reactivity. In acetone, there were two methyl groups and a more positive inductive effect results in the least reactivity towards the nucleophilic addition.