Low-temperature NMR of ɛ-caprolactam

Autor: Gerd Borgen, Frode Rise
Rok vydání: 1993
Předmět:
Zdroj: Magnetic Resonance in Chemistry. 31:51-53
ISSN: 1097-458X
0749-1581
DOI: 10.1002/mrc.1260310110
Popis: The conformation of e-caprolactam (1-azacycloheptan-2-one) was studied by low-temperature 2 D 1 H and 13 C NMR. Only one conformer was found in solution from the 13 C NMR spectra recorded down to -155 o C. This conformer was shown, by infrared spectroscopy, to be the same as that found in the crystals of e-caprolactam. A conformational process with a free energy of activation of 43 kJ mol -1 , coalescence temperature -65 o C, was interpreted as geminal 1 H exchange. The assignments of the 13 C and 1 H shifts were made by 2 D NMR. Splitting of all averaged signals for germinal protons into axial and equatorial signals was demonstrated at -100 o C
Databáze: OpenAIRE