Why interconversion in tautomers is so rapid?

Question

Looking at the examples in Tautomer on Wikipedia, it seems that the hydrogen needs to travel a significant distance (~20Å) for the interconversion to take place. What lets it happen so fast? Why interconversion is preferred over maintaining its position?

Tautomer examples (source)

I think this is too similar to your other question to deserve its own entry. You can just edit the other question adding a small sentence asking about tautomerisation kinetics. — Nicolau Saker Neto, Apr 04 '15 at 18:06
Tautomerisation doesn't proceed by an intramolecular mechanism generally, and it is also rarely fast. — J. LS, Apr 05 '15 at 07:49
@J.LS, on Wikipedia it says "Because of the rapid interconversion, tautomers are generally considered to be the same chemical compound.", but I don't really know what "rapid" actually means in this context. — Sparkler, Apr 06 '15 at 15:23
I think that refers to the fact that interconversion is fast enough that you get equilibrium population of tautomers. — J. LS, Apr 06 '15 at 18:10

Oscar Lanzi · Answer 1 · 2019-01-31T20:27:54.843

3

If you are using a protic solvent (the most common situation when you're dealing with polar functional groups), then you are "cheating" because the solvent can generate its own proton transfers, making the reaction look rapid.

edited Jan 31 '19 at 20:27

answered Jan 01 '19 at 13:13

Oscar Lanzi

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Why interconversion in tautomers is so rapid?

1 Answers1