Torsional angles in N-substituted benzamides and related compounds by carbon-13 N.M.R. chemical shifts

1981 ◽  
Vol 34 (5) ◽  
pp. 957 ◽  
Author(s):  
CW Fong ◽  
HG Grant
Keyword(s):  
Steric Effect ◽  
Chemical Shifts ◽  
Steric Interaction ◽  
Hydrogen Atoms ◽  
Ring Inversion ◽  
Nitrogen Inversion ◽  
Substituted Benzamides ◽  
Substituent Constants ◽  
Torsional Angles ◽  
Related Compounds

The torsional angles in 30 N-substituted benzamides and related compounds have been estimated by the use of the 13C substituent chemical shifts of the meta and para carbon atoms. Steric interaction between the N-substituted groups and the ortho hydrogen atoms of the benzene ring is the major determinant of non-planarity in these systems. A linear relationship between steric substituent constants of the N-substituted groups of some benzamides and the torsional angles is proposed. Dynamic processes involving rotation about the C-N bond, nitrogen inversion and ring inversion contribute a dynamic steric effect to the overall steric interaction. The preferred conformations of some N-substituted groups is also discussed.

Torsional angles and substituent effects in phenyl-substituted azoles by carbon-13 N.M.R. chemical shifts

1980 ◽  
Vol 33 (8) ◽  
pp. 1763 ◽  
Author(s):  
CW Fong
Keyword(s):  
Benzene Ring ◽  
Inductive Effect ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Structural Deformation ◽  
Steric Interaction ◽  
Hydrogen Atoms ◽  
Ortho Hydrogen ◽  
Azole Ring ◽  
Torsional Angles

The torsional angles in 31 N-phenyl-substituted azole derivatives have been estimated by use of the 13C substituent chemical shifts of the meta and para carbon atoms. Steric interaction between the C 5 substituent on the azole rings and the ortho hydrogen atoms of the benzene ring is the major cause of non-planarity in these compounds. The azole rings undergo structural deformation with varying substituents on the azole ring. The inductive effect of a number of azole and azolium rings is discussed.

17O NMR study of ortho and alkyl substituent effects in substituted phenyl and alkyl esters of benzoic acids

2011 ◽  
Vol 76 (12) ◽  
pp. 1737-1763 ◽  
Author(s):  
Vilve Nummert ◽  
Vahur Mäemets ◽  
Mare Piirsalu ◽  
Signe Vahur ◽  
Ilmar A. Koppel
Keyword(s):  
Chemical Shifts ◽  
Substituent Effects ◽  
Alkyl Substituent ◽  
Ester Group ◽  
Carbonyl Oxygen ◽  
Steric Interaction ◽  
Alkyl Esters ◽  
17O Nmr ◽  
Nmr Study ◽  
Substituent Constants

17O NMR spectra for 44 ortho-, meta- and para-substituted phenyl and alkyl benzoates (C6H5CO2C6H4-X, C6H5CO2R) at natural abundance in acetonitrile were recorded. Substituent effects on the 17O NMR chemical shifts, δ(17O), of the carbonyl oxygen and the single-bonded phenoxy (OPh) and alkoxy (OR) oxygens have been studied. The δ(17O) values of the carbonyl oxygen for para derivatives showed a good correlation with the σ° constants. The δ(17O) values of carbonyl oxygen for ortho derivatives were found to be described well with the Charton equation containing the inductive, σI, resonance, σ°R, and steric, EsB, substituent constants in case the data treatment was performed separately for electron-donating +R and electron-attracting –R substituents. The electron-donating +R ortho and para substituents in substituted benzoates caused shielding and the electron-withdrawing –R substituents produced deshielding of the O signal. The steric interaction of ortho substituents with the ester group decreased the electron density at the carbonyl oxygen. In alkyl benzoates the δ(17O) values were found to be described well with the inductive, σI, and the steric, EsB, substituent constants.

The High Resolution NMR Spectra of Pesticides. II. The DDT-Type Compounds

1969 ◽  
Vol 52 (5) ◽  
pp. 1074-1092 ◽  
Author(s):  
L H Keith ◽  
A L Alford ◽  
A W Garrison
Keyword(s):  
Nuclear Magnetic Resonance ◽  
High Resolution ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Aromatic Rings ◽  
Nuclear Magnetic Resonance Spectra ◽  
High Resolution Nmr ◽  
Related Compounds ◽  
Deshielding Effect

Abstract The high resolution nuclear magnetic resonance spectra of the DDT class of pesticides and related compounds are discussed, including a study of the resonances of the aromatic protons as they are affected by various substiluents. The CCl3 moiety on the α-carbon strongly deshields the ortho protons on the aromatic rings, and this deshielding effect is greatly enhanced by substitution of a chlorine ortho rather than para on the aromatic ring. These deshielding effects are explained by a consideration of the electronegativity of the substituents and the stereochemistry of the molecule. The chemical shifts and coupling constants are tabulated.

17O NMR spectra of the 1,6-anhydro-β-D-hexopyranoses and related-compounds. Determination of configurational effects on the chemical shifts

1992 ◽  
Vol 30 (4) ◽  
pp. 312-319 ◽  
Author(s):  
Jürgen Lauterwein ◽  
Jürgen Schulte ◽  
Martin Schumacher ◽  
Miloslav Černý
Keyword(s):  
Nmr Spectra ◽  
Chemical Shifts ◽  
17O Nmr ◽  
Related Compounds

NMR-spektroskopische Untersuchungen an 1,1-Thiophendioxid und verwandten Verbindungen / NMR Spectroscopical Investigations of Thiophene 1,1-Dioxide and Related Compounds

1984 ◽  
Vol 39 (7) ◽  
pp. 915-920 ◽  
Author(s):  
Herbert Meier ◽  
Thomas Molz ◽  
Heinz Kolshorn
Keyword(s):  
Computer Simulation ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Multiple Resonance ◽  
Nmr Data ◽  
Cyclic Diene ◽  
Related Compounds ◽  
C Nmr

The 1H and 13C NMR data of thiophene 1,1-dioxide (3) and related compounds, especially of the precursor 2 and the consecutive product 5 are evaluated by computer simulation and multiple resonance. Chemical shifts and coupling constants reveal that 3 has the character of a cyclic diene. Diatropic or paratropic effects can be excluded.

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