Step 1: Understanding the Concept:
Alkyl cyanides (also known as nitriles) possess a functional group consisting of a carbon atom triple-bonded to a nitrogen atom (\(-C \equiv N\)). This group is highly unsaturated and susceptible to reduction. Reduction in organic chemistry involves the addition of hydrogen atoms across multiple bonds. When Sodium (\(Na\)) is used in a solvent like ether or ethanol, it acts as a chemical reducing agent. In this heterogeneous reaction, sodium atoms donate electrons to the nitrile group, while the solvent (usually an alcohol added to the ether or the ether system itself in specific setups) provides the protons needed to complete the reduction. This specific conversion of nitriles to amines using active metals is a fundamental transformation in nitrogen chemistry.
Step 2: Key Formula or Approach:
The reaction described is essentially the Mendius Reaction. The general chemical equation for the reduction of an alkyl cyanide is:
\[ R-C \equiv N + 4[H] \xrightarrow{Na / \text{solvent}} R-CH_{2}-NH_{2} \]
The reduction is a multi-step process where:
1. The triple bond is converted to a double bond (imine stage).
2. The double bond is further reduced to a single bond (amine stage).
The result is a saturated carbon atom and a saturated nitrogen atom.
Step 3: Detailed Explanation:
Let us break down the mechanism and the nature of the product:
1. Starting Material: The reactant is \(R-C \equiv N\). Here, the carbon of the nitrile group is bonded to one alkyl group (\(R\)) and triple-bonded to Nitrogen.
2. Addition of Hydrogen: During the reduction with Sodium, four hydrogen atoms are added to the functional group. Two hydrogen atoms are added to the carbon atom, turning it into a methylene group (\(-CH_{2}-\)). Two hydrogen atoms are added to the nitrogen atom, turning it into an amino group (\(-NH_{2}\)).
3. Nature of the Product: The resulting molecule has the formula \(R-CH_{2}-NH_{2}\). In this structure, the Nitrogen atom is attached to only one alkyl-derivative carbon. By definition, an amine where the Nitrogen is bonded to only one carbon atom is a primary amine.
4. Comparison with other options:
- A secondary amine would require the Nitrogen to be bonded to two different carbon atoms, which cannot happen through simple reduction of a nitrile.
- Alkenes and Alcohols do not contain nitrogen, so they cannot be formed as the primary product from a nitrogen-containing nitrile.
This reaction is a classic method used in laboratories to "ascend" the amine series, as the product amine contains one more carbon than the starting alkyl halide used to make the cyanide.
Step 4: Final Answer:
The reduction of an alkyl cyanide with sodium in ether leads to the formation of a primary amine.
Hence, option (1) is the correct answer.