Question

Complete the following reaction:
${C_6}{H_5}CN + {H_2}/Ni \to ?$
A.${C_6}{H_5}C{H_2}C{H_2}N{H_2}$
B.${C_6}{H_5}C{H_2}N{H_2}$
C.${C_6}{H_5}C{H_2}N{H_2}$
D.${C_6}{H_5}N{H_2}$

Answer 1

Amines are functional groups which are derivatives of ammonia. The hydrogen atom of a compound is replaced by an alkyl or aryl group to form amines. When nitriles undergo hydrogenation process in the presence of a suitable catalyst are reduced to amines with one carbon atom increased as compared to the starting amine.
$R - CN + {H_2}/Ni \to RC{H_2}N{H_2}$

Complete answer:
- Amines are functional groups which are derivatives of ammonia. The nitrogen atom of the amines is trivalent and has an unshared pair of electrons and is therefore sp3 hybridised and amines have pyramidal geometry.
- The hydrogen atoms in a compound are replaced by the alkyl or aryl groups to form amines. This replacement of hydrogen atoms determines the classification of amines into primary, secondary and tertiary amines. Lower amine members are soluble in water as they form hydrogen bonds with water molecules. The solubility of amines decreases with increase in size as with increasing size, the hydrophobic alkyl part increases.
- Nitriles are reduced when they undergo hydrogenation reaction under catalytic effect to form primary amines. This reaction is used to obtain amines with one carbon atom more than the amine with which the reaction was carried.
Thus, for the above given question we use this process of reduction of nitriles.
${C_6}{H_5}CN + {H_2}/Ni \to {C_6}{H_5}C{H_2}N{H_2}$

Therefore, we conclude that option (B) is correct.
Note:
Amines are basic in nature and therefore when they react with acids they form salts. When these amine salts react with bases like $NaOH$, the parent amine is returned. Amines are soluble in water but insoluble in organic solvents. The reaction of amines with mineral acids gives ammonium salts which determine their basic character.