Tautomer distinguishing from resonance

Tautomers are isomers. They have different cr bond networks, which clearly distinguishes them from resonance structures. The most important kinds of tautomers are carbonyl-enol tautomers, as in the preceding example. Tautomerization is a chemical equilibrium that occurs very rapidly in acidic or basic media it should not be confused with resonance, which is not an equilibrium at all. 

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