Explain why secondary amines are more basic than primary amines.

Explanation

As amines are electron rich they have tendency to accept proton and so forms the H- bonds. On the basis of H- bonding stability order is: (`1^(@)` amine> `2^(@)` amine> `3^(@)`amine)
But in ethyl amines there will be some steric hindrance to H- bonding. So the stability due to +1 effect predominates over stability due to H-bonding and hence stability order is
`underset((2^@))((CH_3CH_2)_2NHgt)underset((3^@))((CH_3CH_2)_3Ngt)underset((1^@))(CH_3CH_2NH_2)`