(a) Guanidine (shown) is about as strong a base as hydroxide ion. Explain why guanidine is a much stronger base than most other amines.
(b) Show why p-nitroaniline is a much weaker base (3 pKb units weaker) than aniline.
(c) Explain why N, N, 2, 6-tetramethylaniline (shown) is a much stronger base than N, N-dimethylaniline.

H3C CH3 HC CH3 NH H C CH3 N N,2,6-tetramethylaniline N, N-dimethylaniline