Concerning the role of the reaction field in the proton shielding of molecules in solution

1967 ◽  
Vol 45 (10) ◽  
pp. 1093-1096 ◽  
Author(s):  
G. Kotowycz ◽  
T. Schaefer
Keyword(s):  
Dielectric Constant ◽  
Chemical Shift ◽  
Solute Molecule ◽  
Proton Chemical Shift ◽  
Square Root ◽  
Reaction Field ◽  
Strong Curvature

It is shown that the strong curvature in some plots of proton chemical shift σ versus the Onsager reaction field E can be removed by plotting the shifts of the solute molecule versus the square root of the dielectric constant of the medium. The resulting values of k in the equation σ = −kE cos θ are fairly consistent and reasonable in magnitude.

Solvents effects on the proton chemical shift and H—H, H—F coupling constants in 1-chloro-1-fluoroethylene. Reaction field and dispersion interactions

1967 ◽  
Vol 45 (10) ◽  
pp. 1111-1118 ◽  
Author(s):  
H. M. Hutton ◽  
T. Schaefer
Keyword(s):  
Dielectric Constant ◽  
Chemical Shift ◽  
Coupling Constants ◽  
Proton Chemical Shift ◽  
Coupling Constant ◽  
Dispersion Interactions ◽  
Proton Proton ◽  
Reaction Field ◽  
Proton Coupling ◽  
Solvent Molecules

The proton chemical shift and the geminal proton–proton and cis proton–fluorine coupling constants in 1-chloro-1-fluoroethylene depend primarily on the dielectric constant of the medium, although this dependence is not given by the Onsager reaction field model. A roughly linear relationship is found with the square root of the dielectric constant. The proton coupling constant decreases algebraically while the cis proton–fluorine coupling constant increases as the dielectric constant of the medium increases. The trans proton–fluorine coupling depends on dispersion interactions with the solvent molecules and increases as these interactions increase. The geminal coupling constant varies between − 3.8 and − 4.8 c.p.s., the cis coupling between 7.6 and 12.3 c.p.s., and the trans coupling between 36.9 and 38.6 c.p.s.

Propriétés physiques et basicité de l'oxydipropionitrile

1984 ◽  
Vol 62 (2) ◽  
pp. 361-362 ◽  
Author(s):  
Jean-Claude Bollinger ◽  
Germaine Yvernault ◽  
Théophile Yvernault ◽  
Raymond Houriet
Keyword(s):  
Dielectric Constant ◽  
Refractive Index ◽  
Dipole Moment ◽  
Chemical Shift ◽  
Gas Phase ◽  
Solubility Parameter ◽  
Donor Number ◽  
Proton Chemical Shift ◽  
Acid Base ◽  
Propriétés Physiques

Physical constants (density, refractive index, viscosity, dielectric constant, dipole moment, solubility parameter) and some basicity parameters (donor number, proton chemical shift variation for CHCl3, gas phase basicity) have been determined for 3,3′-oxydipropionitrile (ODPN) at 25 °C. These results are compared with those for other usual solvents; they permit an explanation of its properties as a solvent for acid–base titrations, and the appearance of homohydrogen bonding in this medium.

Medium dependence of the proton chemical shift and H—H, H—F, F—F coupling constants in 1,1-difluoroethylene

1967 ◽  
Vol 45 (24) ◽  
pp. 3157-3164 ◽  
Author(s):  
C. J. Macdonald ◽  
T. Schaefer
Keyword(s):  
Chemical Shift ◽  
Dipole Moments ◽  
Coupling Constants ◽  
Proton Chemical Shift ◽  
Dispersion Interactions ◽  
Spectral Parameters ◽  
Proton Proton ◽  
Reaction Field ◽  
Solvent Dependence ◽  
Solvent Molecules

The solvent dependence of the proton chemical shift, the geminal proton–proton, the cis and trans proton–fluorine, and the geminal fluorine–fluorine coupling constants in 1,1-difluoroethylene is reported for 25 solvents. The shift and the couplings involving protons depend primarily on the dielectric constant of the medium, but the Onsager reaction field model is inadequate to describe the changes observed. The fluorine–fluorine coupling depends also on dispersion interactions with the solvent molecules. A comparison with the solvent behavior of the spectral parameters of vinyl fluoride, 1-chloro-1-fluoroethylene, and trifluoroethylene indicates the importance, in varying degrees, of reaction field effects, hydrogen bonding, dispersion interactions, the orientation of the solute dipole moments, and the polarizability of specific bonds in the solute molecule in determining their solvent-induced changes.

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