Alkyl halide to carboxylic acid via nitrile

Steps:

• Alkyl halide undergoes SN2 substitution with alcoholic KCN to form R-CN.
• R-CN hydrolyzes with hot aqueous NaOH to R-COONa + NH3.
• The alcoholic medium ensures CN- acts as nucleophile without water interference.
• Aqueous NaOH provides conditions for complete hydrolysis of nitrile.

Why C is correct:

• KCN in C2H5OH generates alcoholic KCN for clean SN2 to nitrile; NaOH(aq) follows standard hydrolysis formula R-CN + 2H2O + NaOH → R-COONa + NH3.

Why the others are wrong:

• A: KCN and C2H5OH listed separately fails to specify alcoholic medium, risking aqueous conditions and alcohol formation.
• B: NaCN(aq) promotes OH- substitution to alcohol, not nitrile; HCl(aq) would protonate without advancing to acid.
• D: HCN lacks nucleophilicity for SN2 on halide; NaOH(aq) alone cannot form nitrile intermediate.

Final answer: C