Thus, the order of basicity
of aliphatic amines should be: primary > secondary > tertiary, which
is opposite to the inductive effect based order Secondly, when the
alkyl group is small, like –CH3 group, there is no steric hindrance to
H-bonding In case the alkyl group is bigger than CH3 group, there will
be steric hinderance to H-bonding Therefore,  the change of nature of
the alkyl group, e