Why is the keto form of nucleotides more stable than the enol?

1 Answer
Apr 5, 2018

Tautomerization of enols following hydration of alkynes makes the most common product ketones, rather than the "desired" alcohol.

In the presence of any protons (which let's be honest, they're everywhere), enols' #pi# bonds will eat them up and transform into a ketone via a resonance-stabilized intermediate.

Any good chemist or physicist will go to first principles to answer this really. So I'll brisk over the physics behind this.

Ketone conversion from enols is very thermodynamically favorable and very fast where there are protons around.

Even if glassware in the lab is cleaned thoroughly (I remember when my TA used to command this, haha) trace amounts of protons will always adsorb onto the glass. So it's very hard to isolate an enol.

It's believed to proceed via the following mechanism,