Amines have a lone pair of electrons and can act as proton acceptors (bases). The base strength depends on the electron density on the nitrogen atom. Molecules with greater electron densities are able to attract protons more strongly and are therefore stronger bases.Alkyl groups release electrons towards the nitrogen atom (positive inductive effect) whilst the benzene ring is electron withdrawing (negative inductive effect) and the lone pair on the nitrogen overlaps with the delocalised pi electrons and is partly delocalised into the ring. The nitrogen attached to the benzene ring is a weaker electron pair donor and therefore less attractive to protons so is a weaker base. The order of basicity is tertiary > secondary > primary > ammonia > phenylamine