(15N) acetamide in polar solvents: Hindered internal rotation and intermolecular interactions
作者:
Kimiko Umemoto,
Kenichi Ouchi,
期刊:
Organic Magnetic Resonance
(WILEY Available online 1981)
卷期:
Volume 15,
issue 1
页码: 13-17
ISSN:0030-4921
年代: 1981
DOI:10.1002/mrc.1270150104
出版商: John Wiley&Sons Limited
数据来源: WILEY
摘要:
AbstractThe1H spectrum of (15N)acetamide has been measured in dimethyl sulphoxide (DMSO), methyl propyl ketone (MPK), 1,3‐dioxane, 1,4‐dioxane, D2O, acetonitrile and pyridine‐d5at various temperature intervals within the range of 278–343 K. From the temperature dependence of the NMR spectra of the amide protons, the free energy of activation, ΔG≠, for hindered rotation about the central CN bond was determined by means of total line shape analysis in the four solvents DMSO, MPK and the two dioxanes. Observed values of ΔG≠(298 K) (72.7 in DMSO, 70.1 in MPK, 70.0 in 1,3‐dioxane and 70.1 kJ mol1in 1,4‐dioxane) were not very sensitive to the choice of solvent or concentration. The concentration dependence of the internal chemical shift between the amide protons was studied in MPK, D2O, acetonitrile and pyridine‐d5. The free energy of activation and the internal chemical shift are discussed on the basis of solvent‐amide and amide–amide specific hydrogen bonding interactions, and in comparison to the results of molec
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