Question

Write the name of the reagent to convert Ethanenitrile to Ethanal.

Hint:

Stephen's reduction is the specific named reaction used to prepare aldehydes from nitriles in many exam syllabi.

Answer 1

Step 1: Understanding the Concept:
Nitriles (\(-CN\)) can be partially reduced to imines, which upon subsequent hydrolysis yield aldehydes.
Step 2: Detailed Explanation:
1. Stephen's Reduction: Ethanenitrile (\(CH_3CN\)) is reduced with stannous chloride and hydrochloric acid to form an imine hydrochloride, which on hydrolysis gives ethanal.
\[ CH_3CN \xrightarrow{SnCl_2/HCl} CH_3CH=NH \xrightarrow{H_2O} CH_3CHO \]
2. Alternative Reagent: Diisobutylaluminium hydride (DIBAL-H) can also selectively reduce nitriles to aldehydes at low temperatures.
Step 3: Final Answer:
Reagent: Stannous chloride and Hydrochloric acid (\(SnCl_2/HCl\)).