Substituted .gamma.-lactones with vicinal hydrogen atoms. Conformational study by MM2 calculations and coupling constant analysis

1993 ◽  
Vol 58 (1) ◽  
pp. 154-158 ◽  
Author(s):  
Carlos Jaime ◽  
Cristobal Segura ◽  
Immaculada Dinares ◽  
Josep Font
Keyword(s):  
Coupling Constant ◽  
Conformational Study ◽  
Hydrogen Atoms ◽  
Mm2 Calculations

Preparation and Conformational Study of 19β,28-Epoxy-18α-olean-5-ene Derivatives

2006 ◽  
Vol 71 (3) ◽  
pp. 387-410 ◽  
Author(s):  
Martin Dračínský ◽  
Václav Richtr ◽  
Václav Křeček ◽  
Jan Sejbal ◽  
Jiří Klinot ◽  
...  
Keyword(s):  
Double Bond ◽  
Coupling Constants ◽  
Conformational Study ◽  
Hydrogen Atoms ◽  
Vicinal Coupling Constants ◽  
Starting Compound ◽  
New Type ◽  
Type 3

New oleanane type triterpenoids with the 5(6) double bond were prepared using partial demethylation on carbon C-4. The starting compound was 23-hydroxybetulin (1b) and the key reaction was the methylation of 19β,28-epoxy-24-nor-18α-olean-4-en-3-one (3b). The 5(6) double bond was used in preparation of new derivatives with an epoxy or oxo substituent in ring B. The conformation of ring A of new type 3-oxo oleanane derivatives with a double bond or a substituent on ring B was elucidated from vicinal coupling constants of hydrogen atoms in positions 1 and 2.

Analysis of the NMR Spectrum of Phenylethane-1,2-Dithiol

1965 ◽  
Vol 19 (4) ◽  
pp. 124-129 ◽  
Author(s):  
J. W. Forbes ◽  
J. L. Jungnickel
Keyword(s):  
Computer Program ◽  
Experimental Evidence ◽  
Long Range ◽  
Coupling Constants ◽  
Positive Sign ◽  
Coupling Constant ◽  
Hydrogen Atoms ◽  
Nmr Spectrum ◽  
Geminal Coupling ◽  
Sign Alternation

The NMR spectrum of phenylethane-1,2-dithiol has been analyzed completely (except for the aromatic protons) by Reilly's new computer program MARIPI which is based on the Swalen and Reilly programs NMRIT and NMRENI. The geminal coupling constant, J34, was assumed to be negative in accord with the recent theoretical and experimental evidence on the signs of (H,H) coupling constants. The magnitudes of the two vicinal H-C-C-H coupling constants, J35 and J45, indicate that the molecule exists primarily in the two forms with gauche-trans arrangement of the hydrogen atoms on these carbon atoms The H-C-S-H coupling constants, J13, J14, and J25, can be either positive or negative in sign; however, a positive sign is favored in line with the –, +, – pattern of sign-alternation for (H,H) coupling across 2, 3, and 4 bonds. The long-range coupling constants, J15, J23, and J24, are small and probably negative. The very long-range coupling between the S-H protons, J12, is too small to be determined

PRECISION CALCULATION OF THE π-d SCATTERING LENGTH

2011 ◽  
Vol 26 (03n04) ◽  
pp. 589-591
Author(s):  
M. HOFERICHTER ◽  
V. BARU ◽  
C. HANHART ◽  
B. KUBIS ◽  
A. NOGGA ◽  
...  
Keyword(s):  
Virtual Photon ◽  
Charged Pion ◽  
Scattering Length ◽  
Coupling Constant ◽  
Hydrogen Atoms ◽  
Sum Rule ◽  
Pionic Hydrogen ◽  
Pion Nucleon ◽  
Using Data ◽  
Scattering Lengths

We present a calculation of the π-d scattering length in the framework of chiral perturbation theory (ChPT) with focus on virtual-photon effects. Using data on pionic deuterium and pionic hydrogen atoms, we extract the isoscalar and isovector pion–nucleon scattering lengths [Formula: see text] and [Formula: see text], as well as—via the Goldberger–Miyazawa–Oehme sum rule—the charged-pion–nucleon coupling constant [Formula: see text]

Remarks on the diffuse interstellar lines

1967 ◽  
Vol 31 ◽  
pp. 91-93 ◽  
Author(s):  
G. Herzberg
Keyword(s):  
Hydrogen Atoms ◽  
Interstellar Gas

It is suggested that the diffuse interstellar lines are produced in the interstellar gas by molecules consisting of a few hydrogen atoms and one other atom, such as CH4+ or NH4. Diffuseness of the lines is assumed to result from predissociation of these molecules.

SURFACE PLASMA SOURCE OF HYDROGEN ATOMS WITH AN ENERGY OF HUNDREDS eV

1979 ◽  
Vol 40 (C7) ◽  
pp. C7-479-C7-480 ◽  
Author(s):  
V. G. Dudnikov ◽  
G. I. Fiksel'
Keyword(s):  
Plasma Source ◽  
Surface Plasma ◽  
Hydrogen Atoms
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