Question

The correct order of decreasing basic character of the three aliphatic primary amines is

(a) (i) > (ii) > (iii)

(b) (iii) > (ii) > (i)

(c) (i) > (ii) ≈  (iii)

(d) (i) = (ii) = (iii)

Answer 1

Correct Option (a) (i) > (ii) > (iii)

Explanation:

In structure (i), (ii) and (iii) the α-carbon atoms are sp³, sp² and sp hybridised respectively which in turn cause the difference in their s-character, Greater the s-character of an atom, greater will be its electron-withdrawing nature. Thus, sp (50% s-character) hybridised carbon is most electron-withdrawing, while sp³ (25% s-character) is least electron withdrawing. The presence of an electron withdrawing group decreases the basicity of an amine. Thus