Which of the following is Stephen reaction?

Which of the following is Stephen reaction?
  1. $\mathrm{R}-\mathrm{COCl} \xrightarrow[\text { Pd-BaSO }]{\mathrm{H}_2} \mathrm{R}-\mathrm{CHO}+\mathrm{HCl}$
  2. $\mathrm{R}-\mathrm{CN} \xrightarrow[\text { i) } \mathrm{H}_3 \mathrm{O}^{+}]{\text {i) } \mathrm{SnCl}_2, \mathrm{HCl}} \mathrm{R}-\mathrm{CHO}+\mathrm{NH}_4 \mathrm{Cl}$
  3. $\mathrm{R}-\mathrm{CHO} \xrightarrow[\Delta]{\mathrm{Zn}-\mathrm{Hg} \text { conc. } \mathrm{HCl}} \mathrm{R}-\mathrm{CH}_3+\mathrm{H}_2 \mathrm{O}$
  4. $\mathrm{R}-\mathrm{CHO} \xrightarrow[\text { ii) } \mathrm{KOH}, \mathrm{HO}-\mathrm{CH}_2-\mathrm{CH}_2-\mathrm{OH}]{\text { i) } \mathrm{H}_2-\mathrm{NH}_2}$ $\mathrm{R}-\mathrm{CH}_2-\mathrm{R}$

Solution

Nitriles are reduced to imine hydrochloride by stannous chloride in presence of hydrochloric acid which on acid hydrolysis gives corresponding aldehydes. This reaction is called Stephen reaction. $\mathrm{R}-\mathrm{CN} \xrightarrow[\text { ii) } \mathrm{H}_3 \mathrm{O}^{+}]{\text {i } \mathrm{HCl}} \mathrm{R}-\mathrm{CHO}+\mathrm{NH}_4 \mathrm{Cl}$

Asked in: MHT CET 2024 (04 May Shift 1)

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