Déplacement chimique du proton en résonance magnétique nucléaire. I. Calcul du terme diamagnétique en vue de son utilisation à l'étude de la structure des molécules. Application aux éthers vinyliques

1970 ◽  
Vol 48 (20) ◽  
pp. 3154-3163 ◽  
Author(s):  
François Tonnard ◽  
Simone Odiot ◽  
Maryvonne L. Martin
Keyword(s):  
Carbon Atom ◽  
Linear Combination ◽  
Atomic Orbital ◽  
Ethoxy Group ◽  
Vinyl Ethers ◽  
Résonance Magnétique

A relation between the diamagnetic term for a proton bonded to a carbon atom and the linear combination of atomic orbital charges on C and H is established. Proton diamagnetic terms of some vinyl ethers are calculated, and the conformation of ethoxy group in these molecules studied.

Analyse par résonance magnétique nucléaire 13C de la stabilité relative des spirochromènes et des mérocyanines dérivant du méthoxy-3 nitro-5 salicylaldéhyde

1982 ◽  
Vol 60 (21) ◽  
pp. 2644-2653 ◽  
Author(s):  
Michel Maguet ◽  
Michel Le Baccon ◽  
Yves Poirier ◽  
Robert Guglielmetti
Keyword(s):  
Chemical Shift ◽  
Carbon Atom ◽  
Intermediate Position ◽  
Nmr Study ◽  
Résonance Magnétique ◽  
Limiting Value ◽  
C Nmr

Heterocycloimmonium salts generally react with 3-methoxy 5-nitro salicylaldéhyde to give spirochromenes or merocyanines. Only the latter compounds are obtained in the thiazolinic and the benzimidazolinic series. The linking of a paraffinic ring to the merocyanines allows their 13C nmr study. The comparison of their spectra with those of heterocycloimmonium salts stresses a hyperconjugative effect in the thiazolinic and the benzimidazolinic series. The benzoxazolinic series appears to be in an intermediate position: the thermodynamic stabilities of spirochromenes and merocyanines are quite similar. The limiting value of the chemical shift of the carbon atom involved in the spiroannellation of merocyanines, can be approximately determined.

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