2. Compare the pka of pyrrole and imidazole. Which heterocycle is more basic? Applying the Hückel rule of aromaticity, can you explain this difference in reactivity? Protonated pyrrole (2): pka = -3.8 H H + H* H- H `H 1 2 Protonated imidazole (4): pKa = 7.0 H H -N: + H* H H- 4

2. Compare the pka of pyrrole and imidazole. Which heterocycle is more basic? Applying the Hückel rule of aromaticity, can you explain this difference in reactivity? Protonated pyrrole (2): pka = -3.8 H H + H* H- H `H 1 2 Protonated imidazole (4): pKa = 7.0 H H -N: + H* H H- 4

Organic Chemistry

8th Edition

ISBN:9781305580350

Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote

Publisher:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote

Chapter21: Benzene And The Concept Of Aromaticity

Section: Chapter Questions

Problem 21.40P

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Question

Solve Question 2 with detailed explanation

2. Compare the pKa of pyrrole and imidazole. Which heterocycle is more basic? Applying the
Hückel rule of aromaticity, can you explain this difference in reactivity?
Protonated pyrrole (2): pka = -3.8
H
H
H
+ H*
H-
H-
H `H
1
Protonated imidazole (4): pKa = 7.0
H
H
-N:
+ H*
H
::
-H
3
4

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