Question

The correct order of basicity is:

• A. $1>2>3>4$
• B. $4>3>2>1$
• C. $1>3>2>4$
• D. $2>4>1>3$

Answer 1

The correct option is C

$1>3>2>4$

The explanation for the correct option:

Option (C): $1>3>2>4$

1. Basicity is directly proportional to the electron-donating tendency
2. ${\mathrm{CH}}_3-\underset{\underset{{\mathrm{NH}}_2}{|}}{\mathrm{C}}=\mathrm{NH}$ Amidine has two donating centers hence, it is the most basic in nature.
3. Secondary nitrogen is more basic than primary nitrogen because of the presence of more lone pairs
4. Also secondary nitrogen is more basic than primary nitrogen due to $+\mathrm{I}$ effect.
5. ${\mathrm{CH}}_3-\stackrel{\stackrel{\mathrm{O}}{\left|\right|}}{\mathrm{C}}-{\mathrm{NH}}_2$ Acetamide is the least basic because the electron present is delocalized.
6. Hence, it is the correct option

The explanation for the incorrect option:

Option (A): $1>2>3>4$

1. Basicity is directly dependent on the electron-donating group.
2. Dimethyl amine is more basic than ethylamine due to the presence of two electron-donating groups i.e. methyl group is more basic.
3. Hence, it is an incorrect option

Option (B): $4>3>2>1$

1. Basicity is directly dependent on the electron-donating group.
2. ${\mathrm{CH}}_3-\underset{\underset{{\mathrm{NH}}_2}{|}}{\mathrm{C}}=\mathrm{NH}$ Amidine has two donating centers hence, it is the most basic in nature.
3. Hence, it is an incorrect option

Option (D): $2>4>1>3$

1. Basicity is directly dependent on the electron-donating group.
2. ${\mathrm{CH}}_3-\stackrel{\stackrel{\mathrm{O}}{\left|\right|}}{\mathrm{C}}-{\mathrm{NH}}_2$ Acetamide is the least basic because the electron present is delocalized.
3. Hence. it is an incorrect option.

Therefore, the correct order of basicity is $1>3>2>4$