1 -Methyl-5-hydroxy-1,2,3-triazole, solution

AHC(S1), pp. 384,385]. For some derivatives of 119 and 120, the relative stability of oxo isomers may be enhanced. Thus, the predominance of the 5,5-diphenyldihydro-4//-l,2,3-triazol-4-one structure 121 in solution has been confirmed by UV and and NMR studies (93CB103). Also, 1-methyl-5-hydroxy-l,2,3-triazole exists mainly in the tautomeric form 120 (R = Me, R = H) [76AHC(S1), p. 385], although the existence of a minor amount of oxo form 122 was postulated to explain the exchange of the 4-position proton in D2O. 

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