Question
Explain the basic nature of amines with a suitable example.
✓
Answer
The basic nature of amines is due to the presence of a lone pair of electrons on the nitrogen atom.
i. Lewis theory: In terms of Lewis theory, amines are bases because they can share a lone pair of electrons on ‘N’ atom with an electron-deficient species.
For example, trimethylamine shares its lone pair of electrons with the electron-deficient boron trifluoride.$> Me e _3 N:+$ $BF _3 \rightarrow Me _3 N^{+}- B ^{-} F _3>$
ii. Lowry-Bronsted theory: The basic nature of amines is explained by writing the following equilibrium. >
>a. In this equilibrium amine accepts $H^{+}$, hence an amine is a LowryBronsted base. >b. For a stronger base, this equilibrium shifts towards the right, thereby, for stronger bases, the $K _{ b }$ value is larger or the $pK _{ b }$ value is smaller.
i. Lewis theory: In terms of Lewis theory, amines are bases because they can share a lone pair of electrons on ‘N’ atom with an electron-deficient species.
For example, trimethylamine shares its lone pair of electrons with the electron-deficient boron trifluoride.$> Me e _3 N:+$ $BF _3 \rightarrow Me _3 N^{+}- B ^{-} F _3>$
ii. Lowry-Bronsted theory: The basic nature of amines is explained by writing the following equilibrium. >
>a. In this equilibrium amine accepts $H^{+}$, hence an amine is a LowryBronsted base. >b. For a stronger base, this equilibrium shifts towards the right, thereby, for stronger bases, the $K _{ b }$ value is larger or the $pK _{ b }$ value is smaller.Need a full question paper?
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