scholarly journals CP/MASS 13C NMR Spectra of Cellulose Solids: An Explanation by the Intramolecular Hydrogen Bond Concept

1985 ◽  
Vol 17 (5) ◽  
pp. 701-706 ◽  
Author(s):  
Kenji Kamide ◽  
Kunihiko Okajima ◽  
Keisuke Kowsaka ◽  
Toshihiko Matsui
Keyword(s):  
Hydrogen Bond ◽  
Intramolecular Hydrogen Bond ◽  
13C Nmr ◽  
Nmr Spectra ◽  
13C Nmr Spectra ◽  
Intramolecular Hydrogen

Solution Structures of Pyrophthalones, I Structure and Conformation of 1,3-Indandionato-2(2-pyridinium)-betaïn — a 1H/13C NMR Approach

1987 ◽  
Vol 42 (1) ◽  
pp. 31-36 ◽  
Author(s):  
Erhard T. K. Haupt ◽  
Heindirk tom Dieck ◽  
Panayot R. Bontchev
Keyword(s):  
Hydrogen Bond ◽  
Intramolecular Hydrogen Bond ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Complete Analysis ◽  
Solution Structures ◽  
The Stability ◽  
Intramolecular Hydrogen ◽  
Related Compounds ◽  
C Nmr

AbstractThe complete analysis of the 1H/13 C NMR spectra of α-Pyrophthalone and related compounds demonstrates that the earlier static planar description of the molecules is invalid for polar sol-vents, and here the stability of any intramolecular hydrogen bond is small.

The intramolecular hydrogen bond in some β-nitroalcohols. Chemistry of nitroalkanes. Part CXIX

1977 ◽  
Vol 55 (13) ◽  
pp. 2504-2509 ◽  
Author(s):  
E. Lipczyńska-Kochany ◽  
T. Urbański
Keyword(s):  
Hydrogen Bond ◽  
Experimental Evidence ◽  
Intramolecular Hydrogen Bond ◽  
Infrared Absorption ◽  
Nmr Spectra ◽  
Absorption Bands ◽  
Intramolecular Hydrogen ◽  
Infrared Absorption Bands

New experimental evidence is given on the existence of an intramolecular hydrogen bond in β-nitroalcohols between the nitro and hydroxylic groups. The conclusion is based on examination of na → π* and infrared absorption bands and nmr spectra.

scholarly journals Synthesis and isomerism of hydrazones of 2-(5-thioxo-4,5-dihydro-1,3,4-thiadiazol-2-ylthio)acetohydrazide

2007 ◽  
Vol 5 (4) ◽  
pp. 996-1006 ◽  
Author(s):  
Zenonas Kuodis ◽  
Albertas Rutavičius ◽  
Algirdas Matijoška ◽  
Olegas Eicher-Lorka
Keyword(s):  
Hydrogen Bond ◽  
Nitrogen Atom ◽  
Hydroxy Group ◽  
Intramolecular Hydrogen Bond ◽  
1H Nmr ◽  
Nmr Spectra ◽  
1H Nmr Spectra ◽  
Imino Group ◽  
Anti Conformer ◽  
Intramolecular Hydrogen

AbstractNew hydrazones of 2-(5-thioxo-4,5-dihydro-1,3,4-thiadiazol-2-ylthio)acetohydrazide have been obtained and the percentages of anti/syn - conformers were determined. Based on the analyses of 1H NMR spectra, it was concluded that for hydrazones obtained from the 2- hydroxybenzaldehydes and 2’-hydroxycetophenones the ratio between the anti-and syn-conformers depends on the strength of intramolecular hydrogen bond (IMHB) between the nitrogen atom of the imino group and the proton of the 2-hydroxy group. It was shown that increase in IMHB strength results in stabilization of the anti-conformer in solution.

A simple 1H nmr conformational study of some heterocyclic azomethines

1981 ◽  
Vol 59 (8) ◽  
pp. 1205-1207 ◽  
Author(s):  
Francesco A. Bottino ◽  
Maria L. Longo ◽  
Domenico Sciotto ◽  
Michele Torre
Keyword(s):  
Hydrogen Bond ◽  
Chemical Shift ◽  
Intramolecular Hydrogen Bond ◽  
Nmr Spectra ◽  
Variable Temperature ◽  
Rotational Isomerism ◽  
Conformational Study ◽  
Pyrrole Derivatives ◽  
H Nmr ◽  
Intramolecular Hydrogen

The variable temperature 60 MHz 1H nmr spectra of some heterocyclic azomethines exclude the presence of rotational isomerism. Chemical shift values and stereospecific long-range couplings are used to establish that s-trans is the existing conformation. In the case of the pyrrole derivatives a chelated s-trans rotamer is indicated, depending on the presence of an intramolecular hydrogen bond.

13C NMR spectra of hydroxy adamantanes additivity in 13C NMR spectra of dihydroxyadamantanes

1979 ◽  
Vol 44 (7) ◽  
pp. 2230-2237 ◽  
Author(s):  
Jan Schraml ◽  
Harald Jancke ◽  
Günter Engelhardt ◽  
Luděk Vodička ◽  
Josef Hlavatý
Keyword(s):  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Hydroxyl Groups ◽  
13C Nmr Spectra ◽  
Limited Information ◽  
Adamantane Skeleton ◽  
Cyclic Compounds ◽  
Intramolecular Hydrogen ◽  
C Nmr

The 13C NMR spectra of all monohydroxy and ditopic dihydroxy adamantane isomers were measured and the lines assigned. The numbers of the isomers and of the non-equivalent carbon atoms permitted a verification of the simple additivity of the shielding contributions of two hydroxyl groups on the rigid adamantane skeleton in the isomers without a possibility of a direct OH-OH interaction. If such interactions occur, deviations are found. The direction and magnitude of the deviations is in agreement with the current interpretation of 13C chemical shifts in other classes of cyclic compounds. It is concluded that the deviations are not caused by intramolecular hydrogen bonds. The deviations and the values of substituent chemical shifts offer some limited information about the origin of the shielding effects, especially of those dependent on stereochemistry and degree of substitution (γanti effect).

Synthesis and Crystal Structures of 3,6-diacetylated C24 epimeric 20(R)-Ocotillol-Type Saponins

2019 ◽  
Vol 41 (3) ◽  
pp. 452-452
Author(s):  
Juan Liu Juan Liu ◽  
Wen Zhi Wang Wen Zhi Wang ◽  
Jia Zhen Wang Jia Zhen Wang ◽  
Gui Ge Hou Gui Ge Hou ◽  
Qing Guo Meng Qing Guo Meng
Keyword(s):  
Hydrogen Bond ◽  
Single Crystal ◽  
Intramolecular Hydrogen Bond ◽  
1H Nmr ◽  
13C Nmr ◽  
Intermolecular Hydrogen Bond ◽  
Single Crystal Diffraction ◽  
X Ray ◽  
Intramolecular Hydrogen ◽  
Optically Pure

(20R,24R)-epoxy-dammar-3β,6α,12β,25-tetraol (1) and (20R,24S)-epoxy- dammar-3β, 6α,12β,25-tetraol (2) have been synthesized from 20(R)-protopanaxatriol with same polarity. In order to obtain optically pure 1 and 2, (20R,24R)-3,6-diacetyl- 20,24-epoxydammar-3β,6α,12β,25-tetraol (3) and (20R,24S)-3,6-diacetyl-20,24- epoxydammar-3β,6α,12β,25-tetraol (4) were designed and prepared to enhance the polarity difference of C24 epimers. Two suitable crystals of 3 and 4 were obtained and their structures were determined by 1H NMR, 13C NMR, HR-MS and X-ray single-crystal diffraction. The results indicated that the C-24 configuration of 3 and 4 are R-form and S-form, respectively. 3 has two intramolecular hydrogen bond. While there is only one in 4 and the crystal stacking displays that it generates a right-handed helically chiral channel viewing from the crystallographic b axis via classical O–H•••O intermolecular hydrogen bond.

Some Considerations Regarding the 1H and 13C Spectra of 4-(1-azulenyl)-2,6-bis(2-heteroaryl-vinyl)- pyrylium and Pyridinium and their Corresponding Pyridines

2018 ◽  
Vol 69 (1) ◽  
pp. 64-69
Author(s):  
Liviu Birzan ◽  
Mihaela Cristea ◽  
Constantin C. Draghici ◽  
Alexandru C. Razus
Keyword(s):  
Double Bond ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Pyridinium Salts ◽  
13C Nmr Spectra ◽  
1H And 13C Nmr ◽  
Pyrylium Salts

The 1H and 13C NMR spectra of several 2,6-diheteroarylvinyl heterocycles containing 4-azulenyl moiety were recorded and their proton and carbon chemical shifts were compared with those of the compounds without double bond between the heterocycles. The influence of the nature of central and side heterocycles, molecule polarization and anisotropic effects were revealed. The highest chemical shifts were recorded for the pyrylium salts and the lowest at pyridines, but in the case of the pyridinium salts, the protons chemical shifts at the central heterocycle are more shielded due to a peculiar anisotropy of the attached vinyl groups.

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