This transformation involves the reduction of a nitrile group (-C≡N) to a primary amine (-CH₂-NH₂). Let's analyze the reagents:

Step 1: Understanding the Functional Group Change
The reactant is a nitrile (R-CN), and the product is a primary amine (R-CH₂NH₂). This requires reduction of the triple bond and addition of hydrogen.

Step 2: Evaluating Each Reagent

• Raney Ni/H₂ in THF: This is a catalytic hydrogenation method. It reduces nitriles to primary amines: $R-C\equiv N\stackrel{H_2/\mathrm{Ni}}{\to }R-{\mathrm{CH}}_2-{\mathrm{NH}}_2$. It works.
• NaBH₄ in C₂H₅OH: Sodium borohydride is a mild reducing agent. It does not reduce nitriles to amines. It is ineffective for this transformation.
• LiAlH₄ in (C₂H₅)₂O: Lithium aluminium hydride is a strong reducing agent. It reduces nitriles to primary amines: $R-C\equiv N\stackrel{1.\mathrm{LiAlH}{4}_{\mathrm{}}2.H_{2}O}{\to }R-{\mathrm{CH}}_2-{\mathrm{NH}}_2$. It works.
• BH₃ in THF: Borane (often used as BH₃·THF complex) is also a reducing agent. However, it is not commonly used for the reduction of nitriles. It is more selective for reducing carboxylic acids and is ineffective for nitriles.

Final Answer: The reagents which can be used are Raney Ni/H₂ in THF and LiAlH₄ in (C₂H₅)₂O.

Related Topics & Formulae

Reduction of Nitriles: A key reaction in organic synthesis to prepare primary amines. The general reaction is: $R-C\equiv N+4\left[H\right]\to R-{\mathrm{CH}}_2-{\mathrm{NH}}_2$

Strength of Reducing Agents:

• LiAlH₄ (Strong): Reduces carbonyls, carboxylic acids, esters, nitriles, etc.
• NaBH₄ (Mild): Reduces aldehydes and ketones, but not acids, esters, or nitriles.
• Catalytic Hydrogenation (e.g., H₂/Ni): Reduces alkenes, alkynes, nitro groups, and nitriles.
• BH₃ (Selective): Preferentially reduces carboxylic acids over other carbonyls; does not reduce nitriles.