A 13C nuclear magnetic resonance study of aliphatic ketone protonation in sulfuric acid solutions

1976 ◽  
Vol 54 (5) ◽  
pp. 718-725 ◽  
Author(s):  
Robert A. McClelland ◽  
William F. Reynolds
Keyword(s):  
Sulfuric Acid ◽  
Molecular Size ◽  
Nuclear Magnetic Resonance Study ◽  
Suitable Alternative ◽  
Acidic Solutions ◽  
H Nmr ◽  
Organic Bases ◽  
13C Nuclear Magnetic Resonance ◽  
Sulfuric Acid Solutions ◽  
C Nmr

A 13C nmr investigation of the protonation in sulfuric acid of the aliphatic ketones MeCOR (R = Me, Et, i-Pr, tert-Bu), 3-pentanone, and the cyclic ketones from cyclobutanone through cyclooctanone is reported. With the exception of cyclobutanone which is considerably less basic, these ketones are all very similar in their basicity, with half-protonation in the region 73–78% H2SO4. The acidity dependence of the protonation is discussed; there appears to be a small dependence on molecular size. 13C nmr is shown to be a suitable alternative to 1H nmr in the study of the protonation of weak organic bases in strongly acidic solutions.

1H and 13C nuclear magnetic resonance study of the complexation of uranyl ion with malic acid

1982 ◽  
Vol 60 (8) ◽  
pp. 1007-1018 ◽  
Author(s):  
M. Teresa Nunes ◽  
Victor M. S. Gil ◽  
António V. Xavier
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Malic Acid ◽  
Nuclear Magnetic Resonance Study ◽  
Magnetic Resonance Study ◽  
Molar Ratios ◽  
Nmr Study ◽  
13C Nuclear Magnetic Resonance ◽  
Ph Range ◽  
C Nmr

A full pH range 1H and 13C nmr study was performed of the complexation of UO22+ with malic acid, for variable concentrations and molar ratios. Spectral evidence for the existence of at least five complexes was found, and their stoichiometry and dependence on pH were investigated. Information on the conformation of the bound ligand molecules was also obtained.

Phenol sulfate esters: ultraviolet, infrared, 1H and 13C nuclear magnetic resonance spectroscopic investigation

1978 ◽  
Vol 56 (20) ◽  
pp. 2681-2685 ◽  
Author(s):  
Mark A. Ragan
Keyword(s):  
Spectroscopic Investigation ◽  
Spectroscopic Properties ◽  
Synthetic Methods ◽  
Sulfate Ester ◽  
H Nmr ◽  
Naturally Occurring ◽  
13C Nuclear Magnetic Resonance ◽  
Supplementary Material ◽  
Related Compounds ◽  
C Nmr

Renewed interest in naturally occurring phenol sulfate ester salts has necessitated modem spectroscopic investigation of these compounds. Synthetic methods, plus spectroscopic (uv, ir, 1H nmr, 13C nmr), chromatographic, and electrophoretic properties are given for the potassium salts of phenyl sulfate (1), pyrocatechol disulfate (2), resorcinol disulfate (3), hydroquinone disulfate (4), phloroglucinol mono- (5), di- (6), and tri- (7) sulfates, and for the 2-sulfate (8) and 2,5-disulfate (9) of 1,2,3,5-tetrahydroxybenzene (10). 13C nmr chemical shift effects resulting from the replacement of phenolic —OH with —OSO3K are reported. Spectroscopic properties of the related compounds 1,2,3-tribenzyloxybenzene (11), 2,6-dibenzyloxy-1,4-benzoquinone (12), 2,6-dimethoxy-1,4-benzoquinone (13), 1,3-dibenzyloxy-2,5-dihydroxybenzene (14), and of a tentatively identified 1,3-dibenzyloxy-2,5-dihydroxybenzene monoethyl ether (15) are available as supplementary material.

Paramagnetic effects in flavin spectroscopy. A 13C nuclear magnetic resonance study

1978 ◽  
Vol 56 (8) ◽  
pp. 1045-1051 ◽  
Author(s):  
Donald David Macmurchie ◽  
Robert John Cushley
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nuclear Magnetic Resonance Study ◽  
Paramagnetic Species ◽  
Basic Solution ◽  
Line Broadening ◽  
Magnetic Resonance Study ◽  
Nmr Spectrum ◽  
13C Nuclear Magnetic Resonance ◽  
Specific Line ◽  
C Nmr

Experiments are described whose results indicate that semiquinones produced by intramolecular photoreduction of FMN in basic solution are responsible for specific line broadening observed in the 13C nmr spectrum. Tests with oxidizing agents as well as singlet and triplet quenchers are shown to support this theory rather than the proposition that the paramagnetic species effective in relaxation enhancement is a flavin triplet state. A mechanism for the production of semiquinones and their interaction with the FMN population is discussed.

scholarly journals Dihydroisoindolo[2,1-a]quinazoline-5,11-dione derivatives as potent and selective inhibitors targeting hepatitis B virus

2015 ◽  
Vol 10 (3) ◽  
pp. 612
Author(s):  
Jun-Fei Zhang ◽  
Bo Liu ◽  
Cong-Xin Chen
Keyword(s):  
Sulfuric Acid ◽  
Mass Spectrum ◽  
Hbv Dna ◽  
Isatoic Anhydride ◽  
Silica Sulfuric Acid ◽  
H Nmr ◽  
Viral Antigens ◽  
Potent Inhibition ◽  
B Virus ◽  
C Nmr

<p>The construction of dihydroisoindolo[2,1-a]quinazoline-5,11-dione derivatives (4a–4m), by  the condensation isatoic anhydride, appropriate amines and 2-formylbenzoic acid by using silica sulfuric acid as catalyst was reported. These dihydroisoindolo[2,1-a]quinazoline-5,11-dione derivatives (DIQ) were identified as potent inhibitors of HBV capsid assembly. The newly synthesized dihydroisoindolo[2,1-a]quinazoline-5,11-dione derivatives 4a-4m were characterized by <sup>1</sup>H NMR, <sup>13</sup>C NMR, and Mass spectrum and evaluated for their anti-HBV activity. Majority of the synthesized compounds inhibited the expression of viral antigens at low concentration. But five compounds, 4a, 4b, 4c, 4f, and 4m were shown potent inhibition of HBV DNA replication at submicromolar range. Of these compounds, compound 4a was the most active when compared with lamivudine.</p><p> </p><p> </p>

A 1H and 13C nuclear magnetic resonance study of carnosine

1986 ◽  
Vol 64 (11) ◽  
pp. 2132-2138 ◽  
Author(s):  
Jan O. Friedrich ◽  
Roderick E. Wasylishen
Keyword(s):  
Chemical Shifts ◽  
Imidazole Ring ◽  
Nuclear Magnetic Resonance Study ◽  
Coupling Constants ◽  
Basic Solution ◽  
Magnetic Resonance Study ◽  
Nmr Spectrum ◽  
13C Nuclear Magnetic Resonance ◽  
Nmr Techniques ◽  
C Nmr

The proton and carbon-13 resonance signals of carnosine (β-alanyl-L-histidine) were unambiguously assigned using a variety of nmr techniques including proton–carbon chemical shift correlations, titrations of nmr chemical shifts, coupling constants, and isotope shifts. From the 13C nmr titration, carnosine's three pKa values were estimated to be 2.7, 7.1, and 10.6, and it was found that the imidazole ring existed predominantly as the 3-H tautomer in basic solution. Conformational information about the Cα—Cβ bond and about the N—Cα bond was deduced from observed 3J(C,H) and 3J(H,H) values. The 13C nmr spectrum of carnosine in solution is also compared with that obtained for a solid sample.

X-ray structural and nuclear magnetic resonance study of open chain and macrocyclic thioether complexes

1990 ◽  
Vol 68 (8) ◽  
pp. 1357-1363 ◽  
Author(s):  
C. Robert Lucas ◽  
Shuang Liu ◽  
Michael J. Newlands ◽  
Eric J. Gabe
Keyword(s):  
Nmr Spectra ◽  
Chemical Exchange ◽  
Variable Temperature ◽  
Low Frequency ◽  
Nuclear Magnetic Resonance Study ◽  
Conformational Exchange ◽  
Open Chain ◽  
H Nmr ◽  
Chain Complexes ◽  
C Nmr

Preparations of the thiophenophane and open chain thioether complexes MX2•BBTE(M = Pd; X = Cl, I)(M = Pt; X = Cl) (BBTE = 1,2-bis(benzylthio)ethane) and MX2•L (M = Pd; X = Cl, Br, I, SCN) (M = Pt; X = Cl) (L = 2,5,8-trithia[9](2,5)thiophenophane) are described. The molecular structure of PdBr2•L which contains a weak thiophene-sulfur-to-palladium interaction has been determined: space group P21/n, a = 8.3569(3), b = 16.3254(15), c = 11.1462(3) Å, β = 92.833(4)°, Z = 4, Rf = 0.060, Rw = 0.058. The electronic, low frequency ir, and 13C nmr spectra are described. Variable temperature 1H nmr spectra are discussed and it is concluded that the open chain complexes undergo rapid conformational exchange at room temperature but are configurationally rigid unless the temperature is increased. In contrast, the macrocyclic complexes undergo very limited conformational and no configurational exchange up to their decomposition temperatures. They are also nonfluxional in the same temperature range. Chemical exchange of acidic ligand hydrogens and a metal–ligand dissociative equilibrium were also detected when X = SCN. Keywords: thiophene, thioether, macrocyclic metal complexes.

A structural reinvestigation of 4,6-dinitrobenzofuroxan by 1H, 13C, and 15N nuclear magnetic resonance

1989 ◽  
Vol 67 (3) ◽  
pp. 503-507 ◽  
Author(s):  
F. Terrier ◽  
J. C. Halle ◽  
P. MacCormack ◽  
M. J. Pouet
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Nuclear Magnetic Resonance Study ◽  
H Nmr ◽  
Oxide Group ◽  
Proton Chemical Shifts ◽  
C Nmr ◽  
Nuclear Magnetic

A detailed nuclear magnetic resonance study of 4,6-dinitro-2,1,3-benzoxadiazole N-oxide (DNBF), which includes a 2D INADEQUATE analysis and experiments with samples 15N-labelled at the NO2 groups, is described. The results lead to an unambiguous assignment of the carbon and proton chemical shifts in various solvents. Some 1H and 13C data pertaining to 4,6-dinitro-2,1,3-benzoxadiazole (DNBZ), the deoxygenated analog of DNBF, are also reported, allowing the influence of the N-oxide group on the proton and carbon chemical shifts to be discussed. It is shown that all of the 1H nmr evidence so far reported for the characterization of DNBF σ adducts as arising from nucleophilic addition to the 7-position, i.e., as structure 2a, has no significance. That complexation actually occurs at this position is, however, convincingly demonstrated by 15N data. These also allow us to establish that this process is both kinetically and thermodynamically favored. Keywords: nitrobenzofuroxans, Meisenheimer complexes, 13C nmr of benzofuroxans, 2,1,3-benzoxadiazole N-oxides, nitrobenzofuroxan σ-adducts.

A kinetic and nuclear magnetic resonance study of methylated pyrimidine nucleosides

1983 ◽  
Vol 61 (10) ◽  
pp. 2397-2402 ◽  
Author(s):  
B. D. Allore ◽  
A. Queen ◽  
W. J. Blonski ◽  
F. E. Hruska
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Ph Dependence ◽  
Nuclear Magnetic Resonance Study ◽  
Magnetic Resonance Study ◽  
Pyrimidine Nucleosides ◽  
Spectrophotometric Methods ◽  
H Nmr ◽  
Nmr Data ◽  
The Stability ◽  
C Nmr

Alkylated pyrimidine nucleosides are of interest from the viewpoint of mutagenesis and carcinogenesis. 1H and 13C nmr data are presented for a series of 2′-deoxynucleosides methylated at the O2-, O4-, and N3-positions of the base, and discussed in terms of their physical properties. The pH dependence of the stability of the O2- and O4-methylated 2′-deoxyribosides as well as the corresponding ribosides was examined by 1H nmr and ultraviolet (uv) spectrophotometric methods.

13C nuclear magnetic resonance spectral and conformational analysis of naturally occurring tetrahydrofuran lignans

1979 ◽  
Vol 57 (4) ◽  
pp. 441-443 ◽  
Author(s):  
Sebastião F. Fonseca ◽  
Lauro E. S. Barata ◽  
Edmundo A. Rúveda ◽  
Paul M. Baker
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Conformational Analysis ◽  
Nmr Spectra ◽  
H Nmr ◽  
Naturally Occurring ◽  
Nmr Data ◽  
Benzylic Carbon ◽  
13C Nuclear Magnetic Resonance ◽  
C Nmr

The 13C nmr spectra of the naturally occurring stereoisomers of the tetrahydrofuran lignans were recorded and the signals assigned. Based on these assignments, on the observed sensitivity of the benzylic carbon shifts to the orientation of the aryl groups, and on the comparison with previously reported 1H nmr data, the most probable conformations for the mentioned stereoisomers are suggested.

Hindered Rotation in Poly(N-acyl)iminoalkylenes - A 13C Nuclear Magnetic Resonance Study

1995 ◽  
Vol 50 (9) ◽  
pp. 1404-1411 ◽  
Author(s):  
Bernabé L. Rivas ◽  
Klaus Albert ◽  
Kurt E. Geckeler ◽  
Ernst Bayer
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Cationic Polymerization ◽  
Nmr Spectra ◽  
Nuclear Magnetic Resonance Study ◽  
Side Chain ◽  
Magnetic Resonance Study ◽  
Hindered Rotation ◽  
13C Nuclear Magnetic Resonance ◽  
C Nmr

AbstractPoly(N-acetyl)iminoethylene. poly(N-propionyl)iminoethylene and poly(N-acetyl)-2,2-dimethyliminoethylene were prepared by cationic polymerization in solution of 2-methyl- 2-oxazoline, 2-ethyl-2-oxazoline, and 2,4,4-trimethyl-2-oxazoline respectively. The 13C NMR spectra of the polymers obtained showed different sets of shifts for the carbon atoms of the backbone as well as for the N-acylimino side chain due to the restricted rotation of the Nacylimino group. The temperature dependence of the N-acylimino side chain signals showed a different coalescence behaviour depending on the substituents at both the main and the side chain.

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