[alexmahone]

Q As the base changes from RNH2 to R2NH, to R3N the basicity:

(A) R2NH>R3N>RNH2
(B) RNH2>R3N>R2NH
(C) RNH2>R2NH>R3N
(D) R3N>RNH2>R2NH

My attempt: The steric factor and the inductive effect, together decide the basicity of an amine. The answer key says (A), but could someone please explain why?

Thanks in advance.

[Gregorian]

All amines have approximately the same basicity except for aromatic amines (i.e.aniline) which are much less basic than alkyl amines.

Tertiary amines are more basic than secondary which are more basic than primary which are more basic than ammonia and that is because of the alkyl groups which are electron donating groups (Inductive effect). They are more electron donating groups than hydrogen which makes the nitrogen more negative and so more basic and needing to abstract hydrogens

[macman104]

This question comes up every now and then, there is a good explanation here:

http://www.chemicalforums.com/index.php?topic=23571.msg89592#msg89592