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Determination of the preferred tautomeric form of 4‐nitrohistidine
Author(s) -
Pedroso Enrique,
Grandas Anna,
Ludevid Ma. Dolors,
Giralt Ernest
Publication year - 1986
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570230351
Subject(s) - tautomer , chemistry , imidazole , ring (chemistry) , equilibrium constant , chemical shift , computational chemistry , stereochemistry , organic chemistry
Spectrophotometric p Ka determinations of methyl derivatives of N α ‐acetyl‐4‐nitrohistidine methyl ester 1 have been used to determine the position of the tautomeric equilibrium of 1 . The N 1 ‐H tautomer is the predominant form with an equilibrium constant K T of 48. The conclusion is supported qualitatively by the study of 1 H‐nmr and 13 C‐nmr chemical shifts of the imidazole ring atoms and their changes from neutral to acidic media.