Question
Explain the basic nature of amines with suitable example.
✓
Answer
The basic strength of amines is expressed in terms of $K_b$ or $_pK_b$ value.
According to Lowry-Bron-sted theory the basic nature of amines is explained by the following equilibrium equation.
In this equilibrium amine accepts $H^+$, hence an amine is a Lowry-Bronsted base.
According to Lewis theory, the species which donates a pair of electrons is called a base.
The nitrogen atom in amiqes has a lone pair of electrons, which can be donated to suitable acceptor like proton $H^+$.
The aqueous solutions of amines are basic in nature due to release of free $OH^–$ ions in solutions. Hence amines are Lewis bases. There exists an equilibrium in their aqueous solutions as follows :
$R – NH_2 + H_2O ⇌ RNH_3 + OH^–$
Since $OH^–$ is a stronger base, equilibrium shifts towards left-hand side giving less concentration of $OH^–$.
Here, $K_b$ value is smaller and $_pK_b$ value is larger.
Hence amines are weak bases.
According to Lowry-Bron-sted theory the basic nature of amines is explained by the following equilibrium equation.
In this equilibrium amine accepts $H^+$, hence an amine is a Lowry-Bronsted base.
According to Lewis theory, the species which donates a pair of electrons is called a base.
The nitrogen atom in amiqes has a lone pair of electrons, which can be donated to suitable acceptor like proton $H^+$.
The aqueous solutions of amines are basic in nature due to release of free $OH^–$ ions in solutions. Hence amines are Lewis bases. There exists an equilibrium in their aqueous solutions as follows :
$R – NH_2 + H_2O ⇌ RNH_3 + OH^–$
Since $OH^–$ is a stronger base, equilibrium shifts towards left-hand side giving less concentration of $OH^–$.
Here, $K_b$ value is smaller and $_pK_b$ value is larger.
Hence amines are weak bases.
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