/sup 18/O isotope shift in /sup 15/N NMR spectroscopy. 3. Effects of structure and solvent

Journal Article · Wed Jul 08 04:00:00 EDT 1987 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00248a037· OSTI ID:5954057

Rajendran, G; Santini, R E; Van Etten, R L

Various /sup 15/N, /sup 18/O-labeled compounds were synthesized and the /sup 18/O-induced isotope shifts on their /sup 15/N NMR spectra were measured in order to examine the effects of structural changes on the magnitudes of the shifts. The measured shifts vary greatly, ranging from 0.027 ppm for a nitrile oxide to 0.159 ppm for an isoxazole. The large isotope shifts of isoxazoles compared to oximes and isoxazoline are attributed to the aromatic nature and shorter N-O bond lengths of the isoxazoles. The nature of substituents in the para position of some aromatic aldehyde and ketone oximes affects the magnitude of the /sup 18/O-induced shift. Intramolecular hydrogen bonding significantly decreases the magnitude of the isotope shift in oximes. A study of the effect of solvents on the isotope shifts of three oximes is made. A significant decrease in the isotope shift is observed in solvents having an electron donor atom such as oxygen or nitrogen. This decrease in the magnitude of the isotope shift is ascribed to the formation of hydrogen bonds between the oxime hydroxyl proton and the oxygen or nitrogen of the solvent. Possible applications of the /sup 18/O isotope in /sup 15/N NMR are briefly discussed.

• Research Organization: Purdue Univ., West Lafayette, IN
• OSTI ID: 5954057
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 109:14; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ACETATES
AMINES
AZOLES
CARBOXYLIC ACID SALTS
CHEMICAL SHIFT
DATA
EVEN-EVEN NUCLEI
EXPERIMENTAL DATA
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
INFORMATION
ISOTOPES
ISOTOPIC EXCHANGE
LABELLED COMPOUNDS
LIGHT NUCLEI
MAGNETIC RESONANCE
MOLECULAR STRUCTURE
NITRO COMPOUNDS
NITROBENZENE
NITROGEN 15
NITROGEN ISOTOPES
NUCLEAR MAGNETIC RESONANCE
NUCLEI
NUMERICAL DATA
ODD-EVEN NUCLEI
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
OXAZOLES
OXIMES
OXYGEN 18
OXYGEN ISOTOPES
RESONANCE
SOLVENT PROPERTIES
STABLE ISOTOPES