[briteyellowness]

would the three benzene rings in triphenylamine pull away electron density of the lone pairs on the nitrogen atom and leave it less dense?  so i guess a corollary to that is are benzene rings EDG or EWG?

[Donaldson Tan]

nitrogen is definitely more electronegative than any of the phenyl group.

if you are wondering why triphenylamine is a weak base, it's because the three phenyl groups are very bulky. they sterically hinder any acid-base reaction involving the valence lone pair on the nitrogen atom.

[briteyellowness]

no, i guess in a way i'm wondering with triphenylamine compared to ammonia, which nitrogen would have a greater electron density?

[movies]

Ammonia.  Phenyl groups are kind of unique because they can both donate and withdraw electron density through delocalization.  Each resonance structure that you can draw with the electrons from nitrogen delocalized into the ring will make the nitrogen atom less electron rich.

If you are talking about thermodynamic basicity then you have to also consider sterics since the bulk of the ion will determine how well it can be solvated and therefore how stable it is.  If you're just talking about raw electron density then  sterics won't be as important an effect.

[laotree]

Generally speaking, the bacisity of secondary amine is stronger than primary amine and teriary amine.