1 H NMR Spectra. Part 28: Proton chemical shifts and couplings in three-membered rings. A ring current model for cyclopropane and a novel dihedral angle dependence for 3 JHH couplings involving the epoxy proton

2012 ◽  
Vol 50 (4) ◽  
pp. 305-313 ◽  
Author(s):  
Raymond J. Abraham ◽  
Paul Leonard ◽  
Cláudio F. Tormena
Keyword(s):  
Dihedral Angle ◽  
Nmr Spectra ◽  
Ring Current ◽  
Chemical Shifts ◽  
Current Model ◽  
H Nmr ◽  
Angle Dependence ◽  
Proton Chemical Shifts

Ring currents, local anisotropy, and the problem of the out-of-plane protons: a reinvestigation of the nuclear magnetic resonance spectrum of [10]-paracyclophane

1977 ◽  
Vol 55 (13) ◽  
pp. 2575-2581 ◽  
Author(s):  
Arvind Agarwal ◽  
John A. Barnes ◽  
John L. Fletcher ◽  
Michael J. McGlinchey ◽  
Brian G. Sayer
Keyword(s):  
Ring Current ◽  
Chemical Shifts ◽  
Current Model ◽  
Classical Model ◽  
Local Anisotropy ◽  
Nmr Spectrum ◽  
H Nmr ◽  
Out Of Plane ◽  
Mechanical Approach ◽  
Quantum Mechanical Approach

The1H nmr spectrum of [10]-paracyclophane has been recorded at 220 MHz and the methylene protons assigned on the basis of homonuclear decoupled spectra. Local anisotropic contributions to chemical shifts for protons sited above or near the aromatic ring of [10]-paracyclophane have been calculated using a classical model previously proposed by Grant. The residual incremental shift was shown to follow the Waugh–Fessenden–Johnson–Bovey classical ring current model, but the loop separation originally invoked was shown to be unnecessary. These corrected ring current contributions also correlate very well with the quantum-mechanical approach of Haigh and Mallion.

Effect of the π-Electron Ring Current on the 1H NMR Spectra of 1,1'-Binaphthol Derivatives

1993 ◽  
Vol 58 (1) ◽  
pp. 77-81 ◽  
Author(s):  
Gustavo Marin-Puga ◽  
Václav Horák ◽  
Paris Svornos
Keyword(s):  
High Resolution ◽  
1H Nmr ◽  
Nmr Spectra ◽  
Close Agreement ◽  
Ring Current ◽  
Chemical Shifts ◽  
Current Effect ◽  
H Nmr ◽  
Ring Current Effect ◽  
Cosy Nmr

High resolution 1H NMR spectra of two 1,1'-binaphthols (I, II), two 1,1'-binaphthalenediols (III, IV) and four 1,1'- binaphthalenediols acetates (IIIa - IVa) were obtained and analyzed. The effect of the ring current was evaluated by comparing the chemical shifts of the compounds, assigned through H-H COSY NMR experiments, to those of the corresponding monomers. All experimental chemicals shifts are in close agreement with the theoretical values obtained via the Bovey model for the ring current effect of a benzene moiety.

Conformations of Bridged Diphenyls. IV. Diphenyl Ether Conformations and Proton Chemical Shifts

1973 ◽  
Vol 51 (2) ◽  
pp. 162-170 ◽  
Author(s):  
J. J. Bergman ◽  
E. A. H. Griffith ◽  
B. E. Robertson ◽  
W. D. Chandler
Keyword(s):  
Magnetic Anisotropy ◽  
Ring Current ◽  
Chemical Shifts ◽  
Diphenyl Ether ◽  
Current Model ◽  
Diphenyl Ethers ◽  
Proton Chemical Shifts

The conformationally dependent chemical shifts for the ring protons of some diphenyl ethers can be explained approximately by the ring-current model for benzene magnetic anisotropy. Although the model underestimates the shielding in the region above the plane of the ring it is the best of the models investigated for this purpose.

Preparation and properties of β-ketosulphones of 5-nitrofuran series. Study of transfer of electronic effects through sulphone group

1982 ◽  
Vol 47 (2) ◽  
pp. 617-621 ◽  
Author(s):  
Dana Polakovičová ◽  
Adolf Jurášek ◽  
Vladimír Kvasnička
Keyword(s):  
Linear Dependence ◽  
Quantum Chemical ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Electronic Effects ◽  
H Nmr ◽  
Physical Measurements ◽  
Hammett Constants ◽  
Series Study ◽  
Proton Chemical Shifts

A series of 2-(5-nitro-2-furyl)-2-oxoethylarylsulphones have been synthesized by reaction of 5-nitro-2-bromoacetylfuran with sodium p-X-benzenesulphinates (where X = H, CH3, OCH3, CH3CONH, NH2, N(CH3)2, Cl, NO2) and used for a study of transfer of electronic effects of the substituent through SO2 group. The found linear dependence between the proton chemical shifts in 1H NMR spectra (and pKa values of the CH2 group) and the Hammett constants of the substituents proves the existence of the transfer through SO2 group. The results of physical measurements were compared with the data obtained by quantum-chemical calculations using the EHT method.

scholarly journals 13C and 1H NMR Spectra of Synthetic (25R)-5α-Spirostanes

1999 ◽  
Vol 23 (1) ◽  
pp. 48-49
Author(s):  
Martín A. Iglesias Arteaga ◽  
Carlos S. Pérez Martinez ◽  
Roxana Pérez Gil ◽  
Francisco Coll Manchado
Keyword(s):  
1H Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
1H Nmr Spectra ◽  
H Nmr ◽  
C 23 ◽  
Main Effects ◽  
Nmr Signals

The assignment of 13C and 1H NMR signals of synthetic (25 R)-5α-spirostanes is presented; the main effects on chemical shifts due to substitution at C-23 are briefly discussed.

Chemical shifts of charge-transfer complexes and Buckingham equation

1990 ◽  
Vol 55 (9) ◽  
pp. 2131-2137
Author(s):  
Mahboob Mohammad ◽  
Ather Yaseen Khan ◽  
Tariq Mahmood ◽  
Ismat Fatima ◽  
Riffat Shaheen ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Nmr Spectra ◽  
Charge Transfer Complex ◽  
Chemical Shifts ◽  
Charge Transfer Complexes ◽  
Aprotic Solvents ◽  
Reaction Field ◽  
H Nmr ◽  
Spherical Cavities ◽  
Dipolar Aprotic Solvents

The 1H NMR spectra of the charge-transfer complex of 1-ethyl-4-methoxycarbonylpyridinium iodide have been recorded in various dipolar aprotic solvents. An attempt is made to interpret the chemical shifts in terms of Buckingham's reaction field equation for spherical cavities. A linear dependence has been found between the δ(2,6) values and the square of dielectric function for a spherical cavity, which confirms the validity of the Buckingham equation for this class of compounds.

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