Nuclear magnetic resonance studies. XVI. Oxygen-17 shieldings of some substituted acetophenones

1969 ◽  
Vol 47 (17) ◽  
pp. 3089-3092 ◽  
Author(s):  
D. J. Sardella ◽  
J. B. Stothers
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Steric Hindrance ◽  
Magnetic Resonance Studies ◽  
Nuclear Magnetic

The 17O spectra of some ortho- and para-substituted acetophenones were determined to examine the effect of substituent polarity and steric hindrance on the acetyl oxygen shieldings. The results are compatible with proposals previously advanced on the basis of the 13C shielding data for these compounds.

Nuclear magnetic resonance studies. III. Rotational isomerism of some C-glucosylflavonoid acetates

1965 ◽  
Vol 18 (5) ◽  
pp. 715 ◽  
Author(s):  
RA Eade ◽  
WE Hillis ◽  
DHS Horn ◽  
JJH Simes
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Steric Hindrance ◽  
Chemical Shifts ◽  
Rotational Isomerism ◽  
Bulky Substituent ◽  
Temperature Dependent ◽  
Magnetic Resonance Studies ◽  
Rotational Isomers ◽  
Nuclear Magnetic

The temperature-dependent variations in the spectra of certain C-glucosyl-flavonoid acetates are attributed to the effect of steric hindrance of bulky substituent groups of the sugar and aromatic moieties on the rate of interconversion of the two rotational isomers present. The differences in the chemical shifts of the protons of the two isomers are attributed to differences in the orientation and position of the acetyl and phenyl groups.

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