A reinterpretation of beta, gamma, and delta substituent effects on 13C chemical shifts

1976 ◽  
Vol 54 (19) ◽  
pp. 2985-2995 ◽  
Author(s):  
Helmut Beierbeck ◽  
John K. Saunders
Keyword(s):  
Chemical Shifts ◽  
Substituent Effects ◽  
13C Chemical Shifts

It is shown that β-, γ-, and δ-substituent effects on 13C chemical shifts may be better understood by assuming that the upfield shifts caused by gauche γ-substituents are not due to non-bonded interactions introduced with the γ-group, but that they are due to the removal of the hydrogen on the β-substituent.

Substituent effects on 13C chemical shifts

1972 ◽  
Vol 7 (4) ◽  
pp. 364-369 ◽  
Author(s):  
William B Smith ◽  
Dennis L Deavenport
Keyword(s):  
Chemical Shifts ◽  
Substituent Effects ◽  
13C Chemical Shifts

Carbon-13 chemical shifts of some pyridines, 2,2'-bipyridyls and 1,10-phenanthrolines

1978 ◽  
Vol 31 (6) ◽  
pp. 1255 ◽  
Author(s):  
A Marker ◽  
AJ Canty ◽  
RTC Brownlee
Keyword(s):  
Solvent Effects ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Empirical Correlations ◽  
Electron Densities ◽  
Total Electron ◽  
13C Chemical Shifts ◽  
Methyl Derivatives

13C chemical shifts of pyridine, 2,2'-bipyridyl and 1,10-phenanthroline, and some of their methyl derivatives have been determined. All measurements were made on 0.25 M solutions in CDCl3, thus enabling comparisons of chemical shifts and substituent effects to be made without complications from solvent effects. For the three classes of compounds, common correlations exist between 13C chemical shifts and both CNDO/2 and INDO calculated carbon total electron densities, with the results suggesting that CNDO/2 calculations provide more suitable data for empirical correlations with 13C chemical shifts.

scholarly journals Substituent Effects on 13C Chemical Shifts of Benzoyl Stabilised Phosphonium Ylides.

1976 ◽  
Vol 30b ◽  
pp. 790-791 ◽  
Author(s):  
Paul Frøyen ◽  
David G. Morris ◽  
Rolf Servin ◽  
I. Johnson ◽  
A. Taticchi ◽  
...  
Keyword(s):  
Chemical Shifts ◽  
Substituent Effects ◽  
13C Chemical Shifts

Substituent effects on the 13C chemical shifts of monosubstituted twistanes

1977 ◽  
Vol 55 (17) ◽  
pp. 3161-3165 ◽  
Author(s):  
Helmut Beierbeck ◽  
John K. Saunders
Keyword(s):  
Chemical Shift ◽  
Substituent Effect ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
13C Chemical Shifts ◽  
Bond Interaction ◽  
Chemical Shift Data ◽  
Shift Data ◽  
Deshielding Effect

The 13C chemical shift data for some hydroxy, chloro, bromo, and oxo twistane derivatives are presented and compared to the shifts observed in corresponding adamantanes. The substituent effect at the α and β carbons is more pronounced in twistanes than in adamantanes. The substituent shift induced at an antiperiplanar γ carbon is shown to depend on the presence or absence of 1,3-diaxial hydrogen–hydrogen interactions between the substituted and γ carbons. If such an interaction is present the effect is of shielding whereas if it is absent, the effect is of deshielding. The deshielding effect appears to occur via a through bond interaction.

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