Magnetic nonequivalence in NMR spectroscopy—II. The role of hydrogen bonding in 2,2,4‐trimethylpentane‐1,3‐diol and its monoisobutyrates | Zendy

Fantazier Richard M. | Zendy

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Magnetic nonequivalence in NMR spectroscopy—II. The role of hydrogen bonding in 2,2,4‐trimethylpentane‐1,3‐diol and its monoisobutyrates

Author(s) -

Fantazier Richard M.

Publication year - 1973

Publication title -

organic magnetic resonance

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 0.483

H-Index - 72

eISSN - 1097-458X

pISSN - 0030-4921

DOI - 10.1002/mrc.1270050206

Subject(s) - intramolecular force , hydrogen bond , steric effects , intermolecular force , chemistry , diol , methylene , hydrogen , chemical shift , nuclear magnetic resonance spectroscopy , crystallography , infrared spectroscopy , spectroscopy , infrared , molecule , stereochemistry , organic chemistry , physics , quantum mechanics , optics

The methylene protons in 2,2,4‐trimethylpentane‐1,3‐diol ( 1 ), its 1 ‐isobutyrate ( 2 ) and 3 ‐isobutyrate ( 3 ) monoesters, are magnetically nonequivalent with respect to chemical shift. Under the same experimental conditions, the chemical shift differences are 14·4 Hz, 46·2 Hz and 18·2 Hz for 1 , 2 and 3 , respectively. These nonequivalences were examined as a function of temperature and concentration. The large nonequivalence in 2 is attributed to a highly restricted conformation resulting from intramolecular hydrogen bonding. Less favorable steric interactions result in a substantially smaller contribution of intramolecular hydrogen bonding in 3 , while in 1 intermolecular hydrogen bonding occurs exclusively. Infrared data were obtained in support of these conclusions.

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