Concept:The reaction mechanism depends on the polarity of the substrate and the nature of the attacking reagent.
Solution:- A mixture of \( NaCN \) and an acid generates Hydrogen Cyanide (\( HCN \)) in situ, which provides the strong nucleophile, \( CN^- \).
- The carbonyl carbon is highly electrophilic due to the electron-withdrawing oxygen atom.
- The \( CN^- \) nucleophile attacks this carbon, breaking the \( C=O \) pi bond and adding completely to the molecule to form a cyanohydrin.
- Thus, the mechanism is a Nucleophilic addition reaction.
Why other options are incorrect:Electrophilic addition is typical of non-polar double bonds (alkenes). Substitution requires a leaving group to depart, which does not happen here (the oxygen stays attached).
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