Question

The reaction in which primary amine is obtained as one of the product is

Short answer

The reaction in which a primary amine is obtained as a product is the reduction of a nitrile. The process involves breaking the carbon-nitrogen triple bond in the nitrile (e.g., ethanenitrile) and replacing it with a single bond and hydrogen atoms using a suitable reducing agent like lithium aluminum hydride (LiAlH4) or hydrogen gas (H2) with a transition metal catalyst (e.g., palladium or platinum). The resulting product is a primary amine, such as ethylamine (CH3NH2).

Step-by-step solution

1. Identify the starting nitrile

: First, identify the starting nitrile that will be used in the reduction process. In this example, let's consider the nitrile, ethanenitrile, with a molecular formula of CH3CN.

2. Apply the appropriate reducing agent

: Next, we need to choose a suitable reducing agent that will break the triple bond between the carbon and nitrogen in the nitrile and replace it with a double bond and hydrogen atoms. Typical reducing agents for this purpose include lithium aluminum hydride (LiAlH4) and hydrogen gas (H2) with a transition metal catalyst like palladium or platinum.

3. Deduce the reaction products

: Upon adding the chosen reducing agent (LiAlH4 or H2 and a catalyst), the carbon-nitrogen triple bond in the nitrile will be reduced to a single bond, along with the addition of hydrogen atoms. This leads to the formation of a primary amine as the product. For our example, the product will be ethylamine (CH3NH2).

4. Write the balanced chemical equation

: Finally, we will write the balanced chemical equation for the reduction process, using the chosen reducing agent. Let's use LiAlH4 as the reducing agent for this example: CH3CN (Ethanenitrile) + 4 LiAlH4 (Lithium aluminum hydride) -> CH3NH2 (Ethylamine) + 4 AlH3 (Aluminum hydride) + 4LiC (Lithium carbide) You can also use hydrogenation with a catalyst, such as palladium, in place of lithium aluminum hydride: CH3CN (Ethanenitrile) + H2 (Hydrogen gas) --Pd/C catalyst--> CH3NH2 (Ethylamine)

Key concepts

Nitrile Reduction

Nitrile reduction is a critical chemical process used to synthesize primary amines from nitriles. This reaction involves breaking the triple bond between the carbon and nitrogen atoms in the nitrile. A typical example of a nitrile that may be reduced is ethanenitrile, represented by the molecular formula CH₃CN.

During the reduction process, the nitrile is exposed to a powerful reducing agent that facilitates the addition of hydrogen atoms to the nitrile, transforming the carbon-nitrogen triple bond into a single bond. As a result, a primary amine, which contains a direct attachment of the amino group (-NH₂) to the carbon chain, is formed. Understanding the intricacies of nitrile reduction opens up significant possibilities for creating various amine-based compounds used in pharmaceuticals, agriculture, and manufacturing materials.

Primary Amine

Primary amines are organic compounds that play an essential role in many biological and chemical systems. They are characterized by the presence of a lone amino group (-NH₂) attached to a carbon atom that has only one alkyl or aryl substituent.

A primary amine is differentiated from secondary and tertiary amines by this unique structure. For instance, when ethanenitrile is reduced through a process like nitrile reduction, a primary amine known as ethylamine (CH₃NH₂) is produced. Primary amines are highly reactive due to the lone pair of electrons on the nitrogen, which allows them to engage in various chemical reactions and serve as building blocks for more complex molecules.

Lithium Aluminum Hydride

Lithium aluminum hydride (LiAlH₄) is an inorganic compound that is widely used as a reducing agent in organic chemistry. This white crystalline solid is highly effective for the reduction of nitriles to primary amines.

When it interacts with a nitrile, the LiAlH₄ donates its hydride ion (H-) to the carbon atom of the nitrile, facilitating the conversion of the triple bond into a single bond, and effectively saturating the compound with hydrogen atoms. This conversion results in the formation of a primary amine and by-products such as aluminum hydride (AlH₃) and lithium carbide (LiC). Due to its powerful reducing abilities, handling LiAlH₄ demands caution, as it can react violently with water and air's moisture.

Hydrogen Gas Catalysis

Hydrogen gas catalysis is a cornerstone of chemical synthesis, which involves the addition of hydrogen (H₂) across unsaturated compounds in the presence of a catalyst.

To effect the reduction of a nitrile to a primary amine, hydrogen gas can be used in conjunction with a metal catalyst, such as palladium (Pd) supported on carbon (C), often designated as Pd/C. The catalyst serves to lower the activation energy of the reaction and facilitate the addition of hydrogen atoms to the nitrile. This enables the transformation of the carbon-nitrogen triple bond into a primary amine with far milder conditions than would otherwise be necessary. This method, known as catalytic hydrogenation, is prized for its efficiency and is widely employed in the pharmaceutical and chemical manufacturing industries.