Question

The most reactive compound towards formation of cyanohydrin on treatment with HCN followed by acidification is

• A. benzaldehyde
• B. p-nitrobenzaldehyde
• C. phenylacetaldehyde
• D. p-hydroxybenzaldehyde

Answer 1

Answer: (B)

p-nitrobenzaldehyde

Answer 2

Addition of HCN to a carbonyl compound is a nucleophilic addition reaction. $-\text{N}{{\text{O}}_{\text{2}}}$ group being electron withdrawing increases the polarity (or electron deficiency) of catbonyl carbon and thus, makes the
group of benzaldehyde more reactive towards HCN. 34.