The tautomerism of 1H-pyrazole-3(5)-(N-tert-butyl)carboxamide in the solid state and in solution.
The X-ray crystal structure of 1H-pyrazole-3-(N-tert-butyl)-carboxamide was determined. In the solid state, the 13C and 15N CP/MAS NMR spectra correspond to this tautomer. In solution, both tautomers are present in a ratio that depends on the temperature (at 293 K, 90% 3-substituted/10% 5-substituted). Some unusual 1H, 1H couplings involving the NH proton were observed. DFT (GIAO) calculations were carried out.
Claramunt
Rosa M
RM
Departamento de Química Orgánica y Biología, Facultad de Ciencias, UNED, Senda del Rey 9, E-28040 Madrid, Spain.
García
M Angeles
MA
López
Concepción
C
Trofimenko
Swiatoslaw
S
Yap
Glenn P A
GP
Alkorta
Ibon
I
Elguero
José
J