Choose the correct answer from the following four choices.Statement: P...
- Pyridine is more basic than pyrrole because lone pair of electrons on N in pyridine and pyrrole are different in nature. These form a part of aromatic sextet in pyrrole, while not in pyridine.
- Pyrrole, C4H4NH (in which N contributes a lone pair) has a pKa−3.8 but pyridine (where N is part of the ring's double bond) has a pKa 5.14. Electron pair availability indicates the strength of basicity. In this case, pyridine is the stronger base.
- In pyrrole, the lone pair electrons of the nitrogen atom gets involved with the 2 carbon-carbon double bonds in the 5-member ring to form a conjugated system of pi electrons, leading to greater stability of the molecule.
- Pyridine, on the other hand, already has a stable conjugated system of 3 double bonds in the aromatic hexagonal ring, like benzene. Hence, the lone pair electrons on the N atom in pyridine can be easily donated to a H+ ion or a Lewis acid.
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Choose the correct answer from the following four choices.Statement: P...
- Pyridine is more basic than pyrrole because lone pair of electrons on N in pyridine and pyrrole are different in nature. These form a part of aromatic sextet in pyrrole, while not in pyridine.
- Pyrrole, C4H4NH (in which N contributes a lone pair) has a pKa−3.8 but pyridine (where N is part of the ring's double bond) has a pKa 5.14. Electron pair availability indicates the strength of basicity. In this case, pyridine is the stronger base.
- In pyrrole, the lone pair electrons of the nitrogen atom gets involved with the 2 carbon-carbon double bonds in the 5-member ring to form a conjugated system of pi electrons, leading to greater stability of the molecule.
- Pyridine, on the other hand, already has a stable conjugated system of 3 double bonds in the aromatic hexagonal ring, like benzene. Hence, the lone pair electrons on the N atom in pyridine can be easily donated to a H+ ion or a Lewis acid.
Choose the correct answer from the following four choices.Statement: P...
Now, as both N are sp2, we can simply compare basicity by observing the electronic effects only and as lone pair of N inpyrrole is in resonance so this lone pair can't be donated wheareas the lonepair of N inpyridine is localised and hence ready for donation. Hence,pyridine is more basic than pyrrole .