Geminal Proton-Proton Coupling Constants in CH2[UNK]N-- Systems

1963 ◽  
Vol 85 (24) ◽  
pp. 4041-4042 ◽  
Author(s):  
B. L. Shapiro ◽  
S. J. Ebersole ◽  
G. J. Karabatsos ◽  
F. M. Vane ◽  
S. L. Manatt
Keyword(s):  
Coupling Constants ◽  
Proton Proton ◽  
Proton Coupling ◽  
Geminal Proton

Substituent effects on geminal proton–proton coupling constants

1970 ◽  
Vol 48 (13) ◽  
pp. 2134-2138 ◽  
Author(s):  
Y. L. Chow ◽  
S. Black ◽  
J. E. Blier ◽  
M. M. Tracey
Keyword(s):  
Carbon Tetrachloride ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Coupling Constants ◽  
Proton Proton ◽  
Proton Coupling ◽  
Geminal Proton ◽  
Geminal Coupling ◽  
Hammett Σ Constants

The geminal coupling constants between the non-equivalent benzylic protons of a series of para- and meta-substituted N-benzyl-2-methylpiperidines were shown to be proportional to the Hammett σ constants of the substituents with ρ −1.38 in carbon tetrachloride, −1.21 in benzene, and nearly 0 in 1 N DCl solutions. The ρ values were compared with those of other series and were discussed in terms of the possible conformations involved. The chemical shifts of the benzylic protons of the piperidine derivatives did not give a good correlation with the Hammett σ constants in these solvents.

Approximate self-consistent molecular orbital theory of nuclear spin coupling. III. Geminal proton-proton coupling constants

1970 ◽  
Vol 92 (14) ◽  
pp. 4151-4157 ◽  
Author(s):  
Gary E. Maciel ◽  
J. W. McIver ◽  
N. S. Ostlund ◽  
J. A. Pople
Keyword(s):  
Molecular Orbital ◽  
Nuclear Spin ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Molecular Orbital Theory ◽  
Orbital Theory ◽  
Proton Proton ◽  
Proton Coupling ◽  
Geminal Proton ◽  
Self Consistent

The effect of substituents on geminal proton–proton coupling constants. III

1977 ◽  
Vol 55 (14) ◽  
pp. 2642-2648 ◽  
Author(s):  
Roger N. Renaud ◽  
John W. Bovenkamp ◽  
Robert R. Fraser ◽  
Raj Capoor
Keyword(s):  
Coupling Constants ◽  
Coupling Constant ◽  
Mo Calculations ◽  
Proton Proton ◽  
Effect Of Substituents ◽  
Proton Coupling ◽  
Geminal Proton ◽  
Geminal Coupling ◽  
The Difference ◽  
Methylene Group

The effect of substituents at the 3-position in a series of N-methyl 5,6-dihydro-7H,12H-di-benzo[c,f]azocines on the geminal coupling constants of the C-12 methylene protons has been determined. The slope of the Hammett plot of 2J vs. σ has been found to be +0.20. The orientation of the methylene protons with respect to the π orbitals of the benzene ring bearing the substituent is such that no hyperconjugative effect should be present. The value of +0.20 is in contrast to a previously measured slope of −1.9 for compounds having a geometry ideal for hyperconjugative effects and substantiates the predictions of theoretical MO calculations. As a result, the reliability of this conformational dependence of ρ for use in conformational analysis has been strengthened.A comparison of the data for the azocines with those in the literature indicates the difference between the minimum and maximum effects of a phenyl substituent on a geminal coupling constant of an attached methylene group is 5.5 Hz.

2 J HH -resolved HSQC: Exclusive determination of geminal proton-proton coupling constants

2017 ◽  
Vol 282 ◽  
pp. 18-26 ◽  
Author(s):  
Núria Marcó ◽  
Pau Nolis ◽  
Roberto R. Gil ◽  
Teodor Parella
Keyword(s):  
Coupling Constants ◽  
Proton Proton ◽  
Proton Coupling ◽  
Geminal Proton

Geminal proton-proton coupling constants in methylamine and methylamine hydrochloride

1970 ◽  
Vol 2 (6) ◽  
pp. 625-627 ◽  
Author(s):  
J. L. Sudmeier ◽  
D. R. Murayama
Keyword(s):  
Coupling Constants ◽  
Proton Proton ◽  
Proton Coupling ◽  
Methylamine Hydrochloride ◽  
Geminal Proton

The effect of substituents on geminal proton–proton coupling constants

1967 ◽  
Vol 45 (21) ◽  
pp. 2481-2487 ◽  
Author(s):  
Robert R. Fraser ◽  
Paul Hanbury ◽  
C. Reyes-Zamora
Keyword(s):  
Resonance Spectrum ◽  
Coupling Constants ◽  
Molecular Orbital Theory ◽  
Coupling Constant ◽  
Orbital Theory ◽  
Proton Proton ◽  
Proton Coupling ◽  
Geminal Proton ◽  
Geminal Coupling ◽  
Methylene Group

A series of 2-benzyloxytetrahydropyrans bearing substituents at the ortho, meta, and para positions of the benzene ring have been synthesized. From the nuclear magnetic resonance spectrum of each compound, the geminal coupling constant (J) between the non-equivalent protons of the benzylic methylene group was determined. The geminal coupling constant for the methylene group of several benzyl sulfoxides was also measured. In the ether series it was found that J varied from 11.1 to 13.3 c.p.s. and was directly proportional to the Hammett σ value for the meta and para substituents. In the sulfoxides, however, J was unaffected by the substituent. On the basis of the molecular orbital theory of geminal coupling constants and steric considerations, it is proposed that the sensitivity of J to the substituent effect is dependent upon the conformation of the molecules with respect to the Ar—CH2 bond. The potential utility of this relation as a method of conformational analysis is discussed.

Correlations of proton coupling constants in mono- and di-substituted ethylenes with the inverse of substituent electronegativities. A reconsideration of previous correlations

1967 ◽  
Vol 45 (24) ◽  
pp. 3153-3156 ◽  
Author(s):  
T. Schaefer ◽  
H. M. Hutton
Keyword(s):  
Coupling Constants ◽  
Restricted Range ◽  
Proton Proton ◽  
Proton Coupling ◽  
Geminal Proton ◽  
Two Parameters ◽  
Inverse Proportionality

It is shown that in mono- and di-substituted ethylenes the cis, trans, and geminal proton–proton coupling constants correlate with the inverse of the sum of the substituent electronegativities (one of the substituents may be hydrogen). Previous correlations indicated a direct negative proportionality between the two parameters. This was due to the restricted range of electronegativities over which the correlations were made. There appear to be no strong theoretical objections to the inverse proportionality between coupling constants and substituent electronegativities discussed in this paper.

The Effect of Substituents on Geminal Proton–Proton Coupling Constants; a Conformational Dependence. II

1971 ◽  
Vol 49 (5) ◽  
pp. 755-760 ◽  
Author(s):  
Robert R. Fraser ◽  
Roger N. Renaud
Keyword(s):  
Conformational Analysis ◽  
Solvent Effects ◽  
Coupling Constants ◽  
Methylene Carbon ◽  
Proton Proton ◽  
Proton Coupling ◽  
Geminal Proton ◽  
Methylene Groups ◽  
Geminal Coupling ◽  
Methylene Group

The effect of para-substituents on the geminal coupling constants in benzylic methylene groups has been studied as a function of the conformation at the benzene—CH2 bond. The slopes of Hammett plots of Jgemvs. σ are large (−1.6 to −1.9) when the geometry permits a hyperconjugative interaction between the benzene ring and the methylene group but negligible (+ 0.2) when this interaction is geometrically restricted. The effect of a change in electronegativity of the group attached to the methylene carbon has also been investigated. The change in the slope, ρ, from −1.7 to −1.6 on protonation of the nitrogen attached to the methylene group in a series of isoindolines shows this effect to be extremely small. Solvent effects on ρ are also very small. The potential of this J − σ relation for conformational analysis of benzyl groups is discussed in comparison with existing methods.

21,22-Disubstituted 18α,19βH-Ursane Derivatives with Oxabicyclooctane System in Ring E

1993 ◽  
Vol 58 (1) ◽  
pp. 173-190 ◽  
Author(s):  
Eva Klinotová ◽  
Jiří Klinot ◽  
Václav Křeček ◽  
Miloš Buděšínský ◽  
Bohumil Máca
Keyword(s):  
Spectral Data ◽  
Spin Systems ◽  
Coupling Constants ◽  
Complete Analysis ◽  
Nmr Spectrum ◽  
Proton Proton ◽  
H Nmr ◽  
Proton Coupling ◽  
C Nmr

Reaction of 3β-acetoxy-21,22-dioxo-18α,19βH-ursan-28,20β-olide (IIIa) and 20β,28-epoxy-21,22-dioxo-19α,19βH-ursan-3β-yl acetate (IIIb) with diazomethane afforded derivatives XII-XIV with spiroepoxide group in position 21 or 22, which were further converted into hydroxy derivatives XV and XVII. Ethylene ketals VIII-X were also prepared. In connection with the determination of position and configuration of the functional groups at C(21) and C(22), the 1H and 13C NMR spectral data of the prepared compounds are discussed. Complete analysis of two four-spin systems in the 1H NMR spectrum of bisethylenedioxy derivative Xb led to the proton-proton coupling constants from which the structure with two 1,4-dioxane rings condensed with ring E, and their conformation, was derived.

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