Pyridine like benzene, has six pi-electrons in delocalized pi - orbitals, but unlike benzene the orbitals will be deformed are more attractedtowardsthe nitrogen atom because of its high elecrtonegativity. This is reflected in the dipole of pyridine which has the negative end on Nand the positive end on the nucleus. Pyridine is thus reffered to as a pi - deficient hetrocycle. By analogy with a benzene ring that carries an electron-withdrawing substituent, NO_(2) one would expect it to be deactivated towards electrophilic attack with the help of pi delocalized molecular orbital. We can compare the respective properties of benzene, pyridine, pyrrole, furan and thiophene, which very frequently give aromatic electrophilic and nucleophilic substitution reactions in different positions. The simplest of six membered heterocyclic nitrogen compound is

Pyridine like benzene, has six pi-electrons in delocalized pi - orbita

1.	Pyridine like benzene, has six pi-electrons in delocalized pi - orbitals, but unlike benzene the orbitals will be deformed are more attractedtowardsthe nitrogen atom because of its high elecrtonegativity. This is reflected in the dipole of pyridine which has the negative end on Nand the positive end on the nucleus. Pyridine is thus reffered to as a pi - deficient hetrocycle. By analogy with a benzene ring that carries an electron-withdrawing substituent, NO_(2) one would expect it to be deactivated towards electrophilic attack with the help of pi delocalized molecular orbital. We can compare the respective properties of benzene, pyridine, pyrrole, furan and thiophene, which very frequently give aromatic electrophilic and nucleophilic substitution reactions in different positions. The simplest of six membered heterocyclic nitrogen compound is
Answer» pyrrole quinoine pyridine purine Answer :C