The internal chemical shift - a key to bonding in aromatic molecules. 2. Substituent effects on the carbon-13 magnetic resonance spectra of the 1,4-disubstituted benzenes

1976 ◽  
Vol 80 (18) ◽  
pp. 2023-2027 ◽  
Author(s):  
D. W. Beistel ◽  
W. Dan Edwards
Keyword(s):  
Magnetic Resonance ◽  
Chemical Shift ◽  
Substituent Effects ◽  
Aromatic Molecules ◽  
Magnetic Resonance Spectra

Nuclear Magnetic Resonance Spectra and207Pb Chemical-Shift Tensors of Lead Carboxylates Relevant to Soap Formation in Oil Paintings

2014 ◽  
Vol 68 (3) ◽  
pp. 280-286 ◽  
Author(s):  
Jaclyn Catalano ◽  
Yao Yao ◽  
Anna Murphy ◽  
Nicholas Zumbulyadis ◽  
Silvia A. Centeno ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Chemical Shift Tensors ◽  
Oil Paintings ◽  
Nuclear Magnetic Resonance Spectra ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

Morpholines: stereochemistry and preferred steric course of quaternization

1976 ◽  
Vol 54 (1) ◽  
pp. 126-135 ◽  
Author(s):  
Alan J. Jones ◽  
C. P. Beeman ◽  
M. U. Hasan ◽  
A. F. Casy ◽  
M. M. A. Hassan
Keyword(s):  
Magnetic Resonance ◽  
Chemical Shift ◽  
Nmr Spectra ◽  
Deuterium Nmr ◽  
Free Energies ◽  
Trans Isomers ◽  
Methyl Substitution ◽  
Cis And Trans Isomers ◽  
Cis And Trans ◽  
Magnetic Resonance Spectra

The 13C magnetic resonance spectra of a series of methyl and phenyl substituted morpholines, their hydrochlorides, and methiodides have been determined. The effects of methyl substitution adjacent to oxygen and nitrogen are reasonably equivalent and substituent induced chemical shift parameters derived for the series show favorable agreement with those previously observed in both alicyclic and heterocyclic systems. Results for the cis and trans isomers of phendimetrazine (3,4-dimethyl-2-phenylmorpholine), confirm the preferred chair conformations and configurations cis-3-CH3, cis-2-phenyl (cis) and trans-3-CH3, cis-2-phenyl (trans) for these isomers. The preferred course of quaternization of nitrogen in these systems was determined as axial, using deuteriomethyliodide as a label. This 13C–2H technique relies on the observation of the γ-syn-axial effect and is clearly unambiguous and superior to other methods used in evaluating this mechanism. Product ratios and consequently free energies of this reaction were measured from proton and deuterium nmr spectra.

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