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

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.

Chemical shifts of N14 in the NMR spectra of ammonia and related compounds

1958 ◽  
Vol 2 (1-6) ◽  
pp. 539-550 ◽  
Author(s):  
Bernhard M Schmidt ◽  
L Carlton Brown ◽  
Dudley Williams
Keyword(s):  
Nmr Spectra ◽  
Chemical Shifts ◽  
Related Compounds

The determination of the stereochemistry of epoxides located at the 5,6-positions of decalinic systems: An empirical method based on 13C NMR chemical shifts

2002 ◽  
Vol 80 (7) ◽  
pp. 774-778 ◽  
Author(s):  
Raquel M Cravero ◽  
Guillermo R Labadie ◽  
Manuel González Sierra
Keyword(s):  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Empirical Method ◽  
Nmr Chemical Shifts ◽  
13C Nmr Chemical Shifts ◽  
Empirical Rule ◽  
C Nmr

The 13C NMR spectra of a series of 5,6-epoxides in decalinic systems were studied. The interpretation of the chemical shifts allowed us to formulate an empirical rule to predict the epoxide stereochemistry. A discussion of the scope and limitations of this method and its extension to larger carbon skeletons is also presented.Key words: epoxide stereochemistry, 13C NMR, NMR, decalinic systems, oxiranes.

The 1H NMR spectra and the conformation of 1,6-anhydro-β-D-hexopyranoses and their triacetates

1979 ◽  
Vol 44 (6) ◽  
pp. 1949-1964 ◽  
Author(s):  
Miloš Buděšínský ◽  
Tomáš Trnka ◽  
Miloslav Černý
Keyword(s):  
Nmr Spectra ◽  
Chemical Shifts ◽  
Shift Reagent ◽  
Point Of View ◽  
Coupling Constants ◽  
Lanthanide Shift Reagent ◽  
Pyranose Ring ◽  
H Nmr ◽  
Vicinal Coupling Constants

The 1H NMR spectra of 1,6-anhydro-β-D-hexopyranoses and their triacetates, measured in hexadeuteriodimethyl sulfoxide or deuteriochloroform, confirmed the existence of these compounds in 1C4(D) conformations, with the pyranose ring partly planarized in dependence on the configuration of the substituents in positions C(2), C(3) and C(4). The effects of the substituents on the chemical shifts and the adjusted relationship for the dependence of vicinal coupling constants on the torsion angle are discussed in detail from the point of view of the determination of the configuration and the conformation of 1,6-anhydro-β-D-hexopyranoses and their derivatives. The 1H NMR spectra of triacetates were also measured in the presence of the lanthanide shift reagent, tris(1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedione) europium (III) [Eu.(FOD)3].

Silicon-29 NMR Spectra of Trimethylsilylated Alcohols

1997 ◽  
Vol 62 (5) ◽  
pp. 816-820 ◽  
Author(s):  
Magdalena Kvíčalová ◽  
Jan Čermák ◽  
Vratislav Blechta ◽  
Jan Schraml
Keyword(s):  
Chemical Shift ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Steric Effects ◽  
Almost All ◽  
Derivatives Of ◽  
Related Compounds ◽  
Tms Derivatives

29Si NMR spectra of trimethylsilyl (TMS) derivatives of 26 simple alcohols were measured under standardized conditions (i.e., in sufficiently diluted deuteriochloroform solutions). Due to association with the solvent the chemical shifts are in almost all cases larger than those reported earlier for different solutions. This observation is in agreement with the proposed mechanism of steric effects as being due to sterically controlled association with the solvent. The use of chloroform as a solvent enhances steric effects but at the same time it can reduce small differences due to polar effects in closely related compounds. In the studied class of compounds the gross dependence of the chemical shift on polar effects is not substantially affected by the change of the solvent.

Stéréochimie de β-diols et de leurs dérivés cycliques. XIII. Etude structurale en résonance magnétique nucléaire du proton de dioxanne-1,3-4-spirocyclohexanes: tert-butyl-6-c méthyl-2-r (série II) et diméthyl-2-r, 5-t ou 5-c (série III) dioxanne-1,3-4-t ou -c-spirotriméthyl-3′,3′,5′-cyclohexanes-trans ou -cis

1978 ◽  
Vol 56 (23) ◽  
pp. 3006-3015 ◽  
Author(s):  
Louis Cazaux ◽  
Jean-Pierre Gorrichon ◽  
Yahia Koudsi ◽  
Pierre Maroni
Keyword(s):  
Nmr Spectra ◽  
Chemical Shifts ◽  
Chair Conformation ◽  
Methyl Groups ◽  
Chemical Methods ◽  
Tert Butyl ◽  
Unambiguous Determination ◽  
Résonance Magnétique

The nmr spectra at 60, 100, and 250 MHz in CCl4 of two series of four and eight diastereoisomers of the title 1,3-dioxanespiro-4-cyclohexanes have been analysed. In particular, use of the empirical calculation of chemical shifts allows for the unambiguous determination of structure without the need for chemical methods. With two exceptions, these compounds exist in the double chair conformation. In these molecules the γ intercyclic effect of the methyl groups in position 5 have been calculated. [Journal translation]

17O NMR Spectra of Acylated Ureas and Thioureas

1992 ◽  
Vol 57 (6) ◽  
pp. 1278-1281 ◽  
Author(s):  
Josef Jirman ◽  
Pavel Pech
Keyword(s):  
Chemical Shift ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Electronic Effects ◽  
17O Nmr ◽  
Nmr Chemical Shifts

17O NMR spectra of ten acyl- and diacylureas (I-V) and thioureas (VII-X) were measured. 17O NMR chemical shifts of the ureido oxygen in the ureas range from 240 to 310 ppm, those of the acyl oxygens from 377 to 400 ppm (acetyl groups) and 359 to 389 ppm (benzoyl groups), the half-widths being tens to hundreds Hz. Acylation of urea to the diacyl stage has an almost twice as large effect on the chemical shift of the ureido oxygen than has the monoacylation. From the viewpoint of 17O NMR shifts, no significant differences has been found in the influence of ureido and thioureido groups on the transfer of electronic effects in 1,3-diacylureas and 1,3-diacylthioureas.

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