Comparison of the Electronic Structures of Imine and Hydrazone Side-Chain Functionalities with the Aid of13C and15N NMR Chemical Shifts and PM3 Calculations. The Influence of CN-Substitution on the Sensitivity to Aromatic Substitution

2003 ◽  
Vol 68 (6) ◽  
pp. 2151-2160 ◽  
Author(s):  
K. Neuvonen ◽  
F. Fülöp ◽  
H. Neuvonen ◽  
A. Koch ◽  
E. Kleinpeter ◽  
...  
Keyword(s):  
Electronic Structures ◽  
Chemical Shifts ◽  
Side Chain ◽  
Aromatic Substitution ◽  
Nmr Chemical Shifts ◽  
Pm3 Calculations

Die Weiterleitung von substituenten- induzierten 13C-NMR-chemischen. Verschiebungen in para-substituierten 3-Phenylpropansäure-methylestern / The Transmission of Substituent-Induced 13C NMR Chemical Shifts in para-Substituted 3-Phenyl Propanoic Acid Methyl Esters

1980 ◽  
Vol 35 (7) ◽  
pp. 934-936 ◽  
Author(s):  
R. Radeglia ◽  
S. L. Spassov ◽  
R. Stefanova ◽  
S. D. Sofia
Keyword(s):  
13C Nmr ◽  
Chemical Shifts ◽  
Methyl Esters ◽  
Substituent Effects ◽  
Side Chain ◽  
Parameter Method ◽  
Propanoic Acid ◽  
Nmr Chemical Shifts ◽  
13C Nmr Chemical Shifts ◽  
Acid Methyl

Carbon-13 chemical shifts have been measured of para-substituted 3-phenyl propanoic acid methyl esters. The substituent-induced 13C shifts of the side chain were related to Hammett substituent effects by the dual substituent parameter method. The transmission of substituent effects and the factors that influence 13C shifts are discussed

Polar effects on 13C NMR chemical shifts and rotational barriers of amides. A dual substituent parameters analysis of N,N-dimethyl-3-(5-substituted-2-furyl)-acrylamides

1987 ◽  
Vol 52 (2) ◽  
pp. 409-424 ◽  
Author(s):  
Zdeněk Friedl ◽  
Stanislav Böhm ◽  
Igor Goljer ◽  
Anna Piklerová ◽  
Daniela Poórová ◽  
...  
Keyword(s):  
Substituent Effect ◽  
Chemical Shifts ◽  
Polar Effect ◽  
Dominant Factor ◽  
Side Chain ◽  
Nmr Chemical Shifts ◽  
Resonance Effects ◽  
H Nmr ◽  
Reverse Substituent Effect ◽  
C Nmr

13C NMR chemical shifts were measured for sixteen N,N-dimethyl-3-(5-substituted-2-furyl)-acrylamides in CDCl3 at 21 °C; the barriers of rotation about the C-N bond ΔGc° were determined by using the 1H NMR coalescence method, and the positions of the IR bands of the ν(C=O) stretching vibrations were measured. The dual substituent parameters (DSP) analysis of the 13C NMR chemical shifts for atoms of the vinylcarboxamide side chain -C(3)H=C(2)H-C(1)=O(-N) gives evidence that the chemical shifts for the C-1 and C-3 atoms are controlled primarily by polar effects (δ(C-3) = -3.12σI - 1.03σR0; λ = ρI/ρR = 3.0), which exert a reverse substituent effect on these atoms. Similarly, the DSP analysis of the ΔGc° and ν(C=O) data shows that the dominant factor of the total substituent effect is the polar effect (λ = 1.95 and 1.70, respectively). A confrontation of the results of the DSP analysis with the CNDO/2 calculated electron densities at the corresponding atoms demonstrates that the reactivity of the entire vinylcarboxamide side chain can be well explained in terms of a combination of the polar effect (π-electron polarization) with resonance effects.

Sign in / Sign up

Export Citation Format

Share Document