Question

What is the best reagent to convert nitrile to primary amine?

Answer 1

We know that any organic compound with a ${\text{C}} \equiv {\text{N}}$ functional group is referred to as a nitrite. Inorganic compounds containing the ${\text{C}} \equiv {\text{N}}$ group are referred to as cyanides rather than nitriles. Amines are compounds and functional groups in organic chemistry that include a basic nitrogen atom with a lone pair. When one of the three hydrogen atoms in ammonia is replaced by an alkyl or aromatic group, primary amines form.

Complete answer:
By reacting with ${\text{LiAl}}{{\text{H}}_4}$, nitriles can be transformed to 1° amines. The hydride nucleophile attacks the electrophilic carbon in the nitrile to form an imine anion during this reaction. The imine salt can accept a second hydride to form a dianion after being stabilised by a Lewis acid-base complexation. Water can then be used to convert the dianion to an amine.
The chemical reaction can be given as follows:
$R - C \equiv N\xrightarrow[{2.{H_2}O}]{{1.LiAl{H_4}}}R - C{H_2} - N{H_2}$
(Nitrile) (Primary amine)
LiAlH4 and Sodium/Alcohol are the best reagents for converting nitrile to primary amine. The nitriles can be transformed into a corresponding primary amine through reduction.

Note:
We must be noted that despite its name, the reducing agent, ${\text{LiAl}}{{\text{H}}_4}$, has a very simple structure. In a negative ion, there are four hydrogens ("tetrahydride") around the aluminium. One of the bonds in the negative ion is a coordinate covalent (dative covalent) bond, which uses a hydride ion's lone pair to form a bond with an empty orbital on the aluminium. The carbon-nitrogen triple bond is broken, resulting in a primary amine. The ${\text{N}}{{\text{H}}_{\text{2}}}$ group is found in primary amines.