ISSN:
0749-1581
Schlagwort(e):
NMR
;
13C NMR
;
isotope effects on 13C chemical shifts
;
deuterium isotope effects
;
intramolecular hydrogen bonding
;
hydrogen bond strength
;
olefins
;
β-sulphinylenamines
;
nitroenamines
;
β-diketones (five-membered ring)
;
Chemistry
;
Analytical Chemistry and Spectroscopy
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
A series of intramolecularly hydrogen-bonded enamines, enols and enethiols with ester carbonylic, ketonic carbonylic, thioester carbonylic, nitro and sulphoxide acceptors were investigated to obtain 13C chemical shifts and deuterium isotope effects. Results from 33 new compounds and six remeasurements are compared with already existing data. An important aim was to show that isotope effects on chemical shifts are useful descriptors of hydrogen-bonded systems and not only a parameter proportional to the 13C chemical shifts. Substituent effects were studied and the donors and acceptors ranked according to their abilities to support hydrogen bonding. Steric effects strengthen the hydrogen bonding in cyclic five-membered β-diketones. Plots of two-bond [2ΔC(OD)] vs. four-bond isotope effects [4ΔC(OD)] show that 4ΔC(OD) increases with increasing hydrogen bond strength and that large deviations from this relationship can be an indicator of tautomerism.
Zusätzliches Material:
8 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/mrc.1260330803
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