Account for the following
(i)Primary amines `(R-NH_(2))` have higher boiling point than tertiary amines `(R_(3)N)`
(ii) Aniline does not undergo Friedel - crafts reaction
(iii) `(CH_(3))_(2)` NH is more basic than `(CH_(3))_(3)N` in an aqueous solution

Explanation

(i) Aniline as a Lewis base combine with lewis acid `AICI_(3)` to form salt. Hence, produces positive charge on N-atom and makes it electron with drawing group. Hence, Friedal Craft does not takes place.
`C_(6)H_(5)NH_(2) + AICI_(3) to C_(6)H_(5) ""^(+)NH_(2) AICI_(3)^(-)`
(ii) +1 effect, H-bonding and steric factors which determines the stability of amine in aqueous solution.
In case `(CH_(3))_(2)` NH, one-H-bonding is there. As methyl group is sterically less hindered due to that H-bonding predominates over the stability due to I-effect of `CH_(3)` group.
Hence, `(CH_(3))_(2)` NH is more basic than `(CH_(3))_(3)`N in which there is no Hydrogen bonding.
(iii) `1^(@)` amines have 2-Hydrogen which can form more Hydrogen bonds which needs more energy to break where as in `3^(@)` amine there is no Hydrogen bonding. Hence B.P of `1^(@)` amine in higher than that of `3^(@)` amines.