Solvent effects on the conformations of ortho-nitroanilines

1967 ◽  
Vol 20 (6) ◽  
pp. 1173 ◽  
Author(s):  
ID Rae
Keyword(s):  
Nitro Group ◽  
Proton Magnetic Resonance ◽  
Proton Magnetic Resonance Spectroscopy ◽  
Aromatic Proton ◽  
Intramolecular Hydrogen Bonding ◽  
Resonance Spectroscopy ◽  
Ring Plane ◽  
Polar Solvents ◽  
Resonance Position ◽  
Intramolecular Hydrogen

Proton magnetic resonance spectroscopy has been used to examine the conformations of a number of ortho-nitroanilines in solution. In solvents of low polarity, intramolecular hydrogen bonding maintains the coplanarity of the nitro group and the aromatic ring, but in more polar solvents the nitro group is rotated from the ring plane and this change is evidenced by an upfield shift in the resonance position of the adjacent aromatic proton. The extent of rotation depends on the polarity of the solvent and on the structure of the amine.

Selective deshielding of aromatic protons in some ortho-substituted acetanilides

1968 ◽  
Vol 46 (15) ◽  
pp. 2593-2600 ◽  
Author(s):  
James R. Bartels-Keith ◽  
Ronald F. W. Cieciuch
Keyword(s):  
Hydrogen Bonding ◽  
Magnetic Resonance ◽  
Solvent Effects ◽  
Proton Magnetic Resonance ◽  
Aromatic Proton ◽  
Intramolecular Hydrogen Bonding ◽  
Low Field ◽  
Intramolecular Hydrogen

Certain ortho-substituted acetanilides exhibit proton magnetic resonance signals at unusually low field for the amido proton and the aromatic proton adjacent to the acetamido group. This effect, explicable in terms of intramolecular hydrogen-bonding, has been observed for nitro, carbonyl, sulfamoyl, and sulfonyl substituents. Solvent effects are discussed.

N.M.R. and absorption spectra of nitrotoluidines

1974 ◽  
Vol 27 (4) ◽  
pp. 915 ◽  
Author(s):  
T Yokoyama
Keyword(s):  
Hydrogen Bonding ◽  
Absorption Band ◽  
Nitro Group ◽  
Absorption Spectra ◽  
Long Range ◽  
Chemical Shifts ◽  
Intramolecular Hydrogen Bonding ◽  
Polar Solvents ◽  
Dimethylamino Group ◽  
Intramolecular Hydrogen

N.m.r. chemical shifts of ring protons and absorption spectra of 4-substituted 2-nitroaniline deriva- tives were investigated. It was ascertained that the rotations of dimethylamino and/or 2-nitro groups are influenced by the resonance interaction of the dimethylamino group with 4-substituents and the C1 → C2 absorption band is displaced bathochromically by resonance saturation with 4-substituents. The long-range coupling of NH with H5 in N-methyl-2-nitro-p-toluidine was found to be absent and it is considered that the intramolecular hydrogen bonding of amino hydrogen with the 2-nitro group is ruptured by ROH and polar solvents.

A study of cis-trans isomerism and conformational preferences of thioanilides

1967 ◽  
Vol 45 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Ian D. Rae
Keyword(s):  
Hydrogen Bonding ◽  
Proton Magnetic Resonance ◽  
Proton Magnetic Resonance Spectroscopy ◽  
Resonance Spectroscopy ◽  
Isomer Ratio ◽  
Ring Plane ◽  
Thioamide Group ◽  
Conformational Preferences ◽  
Ortho Substituent ◽  
Do So

In thioanilides, cis-trans isomerism has been clearly differentiated from thioamide – thiolimidic acid tautomerism. The isomer ratio has been related to structural and environmental influences on the thioamide group by means of infrared and proton magnetic resonance spectroscopy. In the thioanilides, the thioamide group does not lie in the ring plane unless constrained to do so by hydrogen bonding between the thioamide proton and a suitable ortho substituent.

Intramolecular hydrogen bonding in some ortho-nitrodiphenylamines and related compounds. A proton magnetic resonance study

1972 ◽  
Vol 25 (10) ◽  
pp. 2145 ◽  
Author(s):  
DJ Gale ◽  
JFK Wilshire
Keyword(s):  
Hydrogen Bonding ◽  
Magnetic Resonance ◽  
Long Range ◽  
Proton Magnetic Resonance ◽  
Intramolecular Hydrogen Bonding ◽  
Temperature Dependent ◽  
Polar Solvents ◽  
Chemical Shift Data ◽  
Intramolecular Hydrogen ◽  
Related Compounds

.Proton magnetic resonance spectra of a wide variety of substituted 2-nitro- and 2,4-dinitro-diphenylamines and related compounds reveal that long-range coupling occurs between the NH proton and the 5-proton of the nitrophenyl ring in non-polar or weakly polar solvents. However, in the case of the 2,4-dinitrodiphenyl- amines, this coupling is absent in highly polar solvents, except when the non-nitrated ring carries powerful electron-donating substituents, e.g. methoxyl or dimethylamino, ortho or para (but not meta) to the NH group. An examination of these phenomena leads to the conclusion that such long-range coupling provides evidence that intramolecular hydrogen bonding occurs between the NH and the 2-nitro groups. N-Benzyl-2,4-dinitroaniline also exhibited similar long-range coupling but, in dimethyl sulphoxide solut'ion, this coupling was temperature-dependent. The chemical shift data of the ortho-nitrodiphenylamines suggest that they adopt a non-planar skew conformation in solution. A six-bond H-F coupling was observed between the fluorine atom and the 6-proton of 2'-fluoro-2,4-dinitrodiphenylamine.

scholarly journals Imaging intelligence with proton magnetic resonance spectroscopy

Intelligence ◽  
2009 ◽  
Vol 37 (2) ◽  
pp. 192-198 ◽  
Author(s):  
Rex E. Jung ◽  
Charles Gasparovic ◽  
Robert S. Chavez ◽  
Arvind Caprihan ◽  
Ranee Barrow ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Proton Magnetic Resonance ◽  
Proton Magnetic Resonance Spectroscopy ◽  
Resonance Spectroscopy

Disulfiram Determination by Proton Magnetic Resonance Spectroscopy and by Colorimetry

1973 ◽  
Vol 56 (1) ◽  
pp. 124-127 ◽  
Author(s):  
Eric B Sheinin ◽  
Walter R Benson ◽  
Myron M Smith
Keyword(s):  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Proton Magnetic Resonance ◽  
Proton Magnetic Resonance Spectroscopy ◽  
Colorimetric Method ◽  
Drug Substance ◽  
Resonance Spectroscopy ◽  
Pmr Spectroscopy ◽  
Label Claim ◽  
Tablet Excipients

Abstract Disulfiram was determined in disulfiram drug substance and tablets by proton magnetic resonance (PMR) spectroscopy at the 100–480 mg level and by a colorimetric technique involving cuprous iodide at the 50 mg level. The tablet excipients do not interfere in the analysis. The average result for disulfiram in a tablet composite was 100.8±1.4% of label claim by PMR and 100.7±0.4% by the colorimetric method.

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