Tautomerism of 1,2,4-triazole

Annular prototropic tautomerism of 1,2,4-triazoles (s-triazoles) involves an equilibrium between three possible forms (26a-26c) (Scheme 13). 

The tautomerism of 1,2,4-triazoles (see Chapter 4.01 and (76AHC(S1)i)) may involve one or more of the following possibilities annular prototropy, prototropy involving both the ring and substituents and tautomerism restricted to the substituent. Only the first two of these will be considered. 

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