Home > Community > Why is the reaction of pyrrole difficult with acid?
Upvote

14

Downvote
+ Science
+ Acids
+ Chemistry
+ Organic chemistry
Posted by
Marco Pagliero

Why is the reaction of pyrrole difficult with acid?

Amy Yu  Follow

If you mean simple pyrrole or an “unperturbed” derivative that has undergone no further reaction, there is only (aromatic) sp2 hybridization in the ring and no stereogenic center there to get racemized.

Perhaps if you could paste in the structure you are referring to we could make sure that we are talking about the same thing.

More

Upvote

VOTE

Downvote
Dennis Leppin  Follow

More basic than what? Given that the nitrogen lone pair is part of the aromatic system I rather think its not more basic than many other things. Is there a “not” missing from your question. If so, all is now solved.

More

Upvote

VOTE

Downvote
Dave Aheto  Follow

The [math]N-H[/math] bond is mildly acidic in pyrrole.

It does react with strong bases like Sodium Hydride and gets deprotonated.

In other words, pyrroles are mild acids themselves, and cannot react with other acids easily.

Protonated pyrroles are unstable and thus hard to form.

More

Upvote

VOTE

Downvote
Bengt Nyman  Follow

pyrrole is a very weak base[Kb~10^-14] because the N electron pair is part of the resonance structure of the molecule. However that means the molecule is much more reactive to electrophilic substitution reactions then benzene is so those electrons are still involved. As usual Wikipedia explains it all:
https://en.wikipedia.org/wiki/Pyrrole

More

Upvote

VOTE

Downvote
Astrophysics and Astronomy  Follow

The lone pair of electrons of N in pyrrole is delocalized .It is part of the pi system, thus involved in aromatization. This lone pair is no longer available for a proton hence it is a weak base.
On the other hand, aniline is already aromatic.Though the lone pair of electrons of -NH2 group of aniline is delocalized over the benzene ring, it is not involved in aromatization. This lone pair is still available for a proton, hence aniline is stronger base than pyrrole.

More

Upvote

VOTE

Downvote
Darren Bord  Follow
Upvote

VOTE

Downvote
Daniel Shai  Follow
Upvote

VOTE

Downvote