Answer to Question #86371 in Organic Chemistry for Gayatri

Question

a) Compare the basicities of pyridine and pyrrole.
b) Give the chemical equations of the following reactions:
i) Condensation of methanal and ethanal in the presence of ammonia
ii) Paal-Knorr reaction
iii) Friedel-Crafts acylation of azole

Answer 1

a) Both pyrrole and pyridine are aromatic molecules.

Aromatic bond of pyrrole if formed of 4 electrons of carbon atoms and a lone pair of nitrogen atom, whereas aromatic bond of pyridine is formed of 5 electrons of carbon atoms and one electron of nitrogen atom.In pyridine lone pair of nitrogen atom does not participate in formation of aromatic bond and therefore nitrogen atom can donate it to form a new bond, what determines higher basidity of pyridine in comparison with pyrrole.

b) Chemical equations:

i) Condensation of methanal and ethanal in the presence of ammonia  

ii) Paal-Knorr reaction  

iii)Friedel-Crafts acylation of azole