Why does tautomerism occur?
Either acid or base can catalyze proton transfer. Hence, tautomerization occurs by two different mechanisms. In the first step of acid-catalyzed tautomerization of the keto form, hydronium ion protonates the carbonyl oxygen atom. Then, water removes the α-hydrogen atom to give the enol.
What are the conditions for Tautomerization to occur?
Tautomerism basically happens in the presence of a catalyst. Acid-catalyst: Here firstly the protonation occurs, cation will be delocalized. Then, deprotonation will occur in the adjacent position of the cation. For base catalysts, deprotonation is the first step.