Nucleophillic Adittion (Base & Acid) / HCN

Nucleophillic Adittion (Base & Acid)

The rate determining step with respect to base-catalyzed nucleophilic addition reaction and acid-catalyzed nucleophilic addition reaction is the step in which the nucleophile acts on the carbonyl carbon.

However, protonation process occurs in the carbonyl oxygen after nucleophilic addition step in case of acid catalysis conditions. The carbocation character of carbonyl structure increases due to protonation and thus makes it more electrophilic.

Addition of Hydrogen Cyanide (HCN)

 Aldehydes and ketones undergo reaction with HCN to produce cyanohydrins. The reaction progresses very slowly by using pure hydrogen cyanide. Hence, base as a catalyst helps to speed up the reaction. This is because catalysis helps in the generation of cyanide ion (CN) which acts as a stronger nucleophile and adds to carbonyl compounds to produce the corresponding cyanohydrin. Cyanohydrins are important synthetic intermediates.