Question

Pyridine, C5H5N, is a 6-membered ring containing the C atoms and the N atom.
Aniline, [C6H5(NH2)] , is a hexagonal ring of 6 C atoms with a NH2 group attached to one of the C atoms in the ring

(1) For each of the above molecules, draw (the) equivalent resonance structure(s) AND resonance structures that involve (introduce) a +1 and a -1 formal charge.

(2) These molecules are Bronsted-Lowry bases – molecules containing at least one atom with a nonbonding electron pair that can form a bond with H+. The N atom in each of these molecules is the one that can from a bond with H+. Pyridine is a stronger base than aniline, meaning that encounters of the pyridine N with H+ result in more N-H+ bond formations (i.e. it reacts with H+ to a greater extent). Using your resonance structures from above, and this description of basicity and base strength, explain why pyridine is the stronger base.

Answer 1

equivalent resonance sructures of pyridine resonance structures that involve (introduce) a +1 and a -1 formal charge O:Z: Pyridine Pyridine NH2 NH2 NH2 lone pair delocalisation lone pair on N The lone pair of electrons on the N of aniline involves in delocalisation over the benzene ring But The lone pair of electrons on the N of pyridine does not involve in delocalisation and it is free and readily available to deprotanate H+ from acids So pyridine is more basic than aniline