Zusammensetzung von Rohsulfan, Nachweis der Sulfane H2S9 bis H2S35 Composition of Crude Sulfane Oil, Identification of the Sulfanes H2S9 to H2S35

1985 ◽  
Vol 40 (2) ◽  
pp. 263-272 ◽  
Author(s):  
Josef Hahn
Keyword(s):  
Narrow Range ◽  
Benzene Solution ◽  
Chemical Shifts ◽  
Upfield Shift ◽  
Downfield Shift ◽  
H Nmr ◽  
Intramolecular Hydrogen ◽  
Hydrogen Bondings ◽  
Nmr Signals

In benzene solution the position of the 1H NMR signals of sulfanes, H2Sn, strongly depends on the sulfur chain length and on the sulfane concentration. Under proper conditions all sulfanes in a mixture are characterized by well-resolved NMR signals showing a downfield shift with increasing length of the sulfur chain. The shift differences between the higher homologues ( n > 8 ) remain nearly constant, thus allowing the assignment of the signals up to H2S35 and the determination of the complete sulfane distribution in crude oils. In sulfane mixtures without solvent as well as in CS2 and CCl4 solutions, however, H2S8 shows the largest downfield shift. The signals of the higher sulfanes overlap in a narrow range at slightly higher field and cannot be characterized except for the CCl4 solution where an assignment up to H2S11 is possible. The chemical shifts are interpreted in terms of inter- and intramolecular hydrogen bondings. The upfield shift caused by benzene is attributed to the formation of H2Sn · benzene complexes.

33S NMR spectra of some sulfonated naphthalenes, naphthols, and their anions

1990 ◽  
Vol 55 (2) ◽  
pp. 446-451 ◽  
Author(s):  
Josef Jirman ◽  
Antonín Lyčka
Keyword(s):  
Aqueous Solutions ◽  
Ammonium Sulfate ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Hydroxyl Group ◽  
Upfield Shift ◽  
Sulfonic Group ◽  
Nmr Chemical Shifts ◽  
Downfield Shift ◽  
Nmr Signals

The 33S NMR spectra of 11 naphthalenesulfonates, 11 hydroxynaphthalenesulfonates, two dihydroxynaphthalenesulfonates, and their anions have been measured in aqueous solutions. The 33S NMR chemical shifts of these compounds exhibit upfield shifts when related to ammonium sulfate as the standard. Introduction of a further sulfonic group causes a small upfield shift (up to 3 ppm). Introduction of a hydroxyl group causes a downfield shift (up to 5 ppm) unless the ring is further substituted. Formation of the anion from hydroxyl group causes an additional downfield shift (up to 6 ppm). The half-width of 33S NMR signals of sulfonated naphthalenes, naphthols, and their anions vary from 10 to 400 Hz.

scholarly journals 13C and 1H NMR Spectra of Synthetic (25R)-5α-Spirostanes

1999 ◽  
Vol 23 (1) ◽  
pp. 48-49
Author(s):  
Martín A. Iglesias Arteaga ◽  
Carlos S. Pérez Martinez ◽  
Roxana Pérez Gil ◽  
Francisco Coll Manchado
Keyword(s):  
1H Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
1H Nmr Spectra ◽  
H Nmr ◽  
C 23 ◽  
Main Effects ◽  
Nmr Signals

The assignment of 13C and 1H NMR signals of synthetic (25 R)-5α-spirostanes is presented; the main effects on chemical shifts due to substitution at C-23 are briefly discussed.

scholarly journals Formation of highly quaternized N,N,N-trimethylchitosan: a chemoselective methodology in aqueous media

2019 ◽  
Vol 91 (3) ◽  
pp. 489-496 ◽  
Author(s):  
Youssouf D. Soubaneh ◽  
Steeven Ouellet ◽  
Caroline Dion ◽  
Jonathan Gagnon
Keyword(s):  
Biomedical Applications ◽  
Chemical Shifts ◽  
Aqueous Media ◽  
Acid Base ◽  
Specific Chemical ◽  
H Nmr ◽  
Low Degree ◽  
Simple Step ◽  
Carbonate Salt

Abstract N,N,N-Trimethylchitosan (TMC) represents a rare example of cationic polysaccharides and numerous studies have shown its potential in biological and biomedical applications. TMC with high degrees of quaternization (DQ) were synthesized from N-methylation of N,N-dimethylchitosan (DMC), which was obtained by reductive alkylation of high molecular weight chitosan in a simple step process and in good yields. The effects of base and solvents were evaluated on the quaternization reaction. The N-methylation of DMC was performed selectively by CH3I and carbonate in water where quaternization was achieved quantitatively with a low degree of O-methylation (17 %). Moreover, the greener procedure allows easy recovery and purification by conventional filtration as a carbonate salt, in which the anion can be exchanged by an acid-base reaction. Quantification of DQ involving 1H NMR integration of methyl peaks must be performed on protonated TMC. High field NMR spectra of TMC showed two specific chemical shifts for anomeric peaks (5.0 and 5.4 ppm) that can also be used for the determination of DQ. This latter method avoids the superimposition problems with other pyranosyl peaks.

Neue Untersuchung über Inhaltsstoffe aus Aloe-und Rhamnus-Arten, XV [1] Homonataloin A und B aus Aloe lateritia: Reindarstellung, Konstitutions-und Konfigurationsaufklärung der Diastereomeren / A New Investigation on Constituents of Aloe and Rhamnus Species, XV [1] Hom onataloins A and B from Aloe lateritia: Isolation, Structure and Configurational Determ ination of the Diastereomers

1991 ◽  
Vol 46 (3-4) ◽  
pp. 177-182 ◽  
Author(s):  
Hans-W. Rauwald ◽  
Deo-D. Niyonzima
Keyword(s):  
Chemical Shifts ◽  
Optical Rotation ◽  
Coupling Constants ◽  
Cd Spectra ◽  
Large Coupling ◽  
H Nmr ◽  
Leaf Exudate ◽  
Hydroxyl Protons ◽  
Nmr Signals ◽  
C Nmr

From the leaf exudate of Aloe lateritia ENGLER the C-glucosyl com pounds homonataloin, aloeresin A and aloesin (synon. aloeresin B) were isolated together with the anthraquinone nataloeem odin-8-methylether and spectroscopically identified. Hom onataloin, widely distributed in Aloe species, was separated into homonataloin A and B by combined TLC and DCCC. In their 1 D and 2D 1H NMR spectra only the shifts of the 2′-hydroxyl protons of both glucosyl residues differ significantly, indicative of 10 S (A) resp. 10 S (B) configurations. In both com pounds the anthrone is in β-position of the D-glucopyranosyl, as determined by the large coupling constants of the anomeric protons. The 13C NMR signals are unambiguously assigned by the use of DEPT, APT and gated-decoupling methods. Only the chemical shifts of C -11 and C -14 show significant differences between both diastereomers due to the adjacent 2′-sugar hydroxyls. The two homonataloins differ mostly in optical rotation and circulardichroism due to different configurations at C - 10 of the anthrone part. The absolute configurations of the diastereomers are determined by correlation of their CD spectra with the CD spectra of the structural analogues 7-hydroxyaloins A and B, which shows that hom onataloin A is the 10 S, 1′S-compound and that homonataloin B has 10 R, 1′S-configuration.

1H NMR studies on the solution conformation of contulakin-G and analogues

2002 ◽  
Vol 80 (8) ◽  
pp. 1022-1031 ◽  
Author(s):  
Lill Kindahl ◽  
Corine Sandström ◽  
A Grey Craig ◽  
Thomas Norberg ◽  
Lennart Kenne
Keyword(s):  
Hydrogen Bond ◽  
Chemical Shifts ◽  
Torsional Rigidity ◽  
Peptide Chain ◽  
Random Coil ◽  
Amide Proton ◽  
Solution Conformation ◽  
Nmr Studies ◽  
H Nmr ◽  
Intramolecular Hydrogen

The conformation of contulakin-G, a bioactive 16 amino acid O-linked glycopeptide (ZSEEGGSNAT*KKPYIL) with the disaccharide β-D-Gal(1[Formula: see text]3)α-D-GalNAc attached to the threonine residue in position 10, has been investigated by 1H NMR spectroscopy. The 1H NMR data for the non-glycosylated peptide and for two glycopeptide analogues, one with the monosaccharide α-D-GalNAc at Thr10 and one with the disaccharide β-D-Gal(1–>3)α-D-GalNAc at Ser7, all of lower bioactivity than contulakin-G, have also been collected. The chemical shifts, NOEs, temperature coefficients of amide protons, and 3JNH,αH-values suggest that all four compounds exist mainly in random coil conformations. Some transient populations of folded conformations are also present in the glycopeptides and turns, probably induced by the sugars, are present in the peptide chain around the site of glycosylation. In the two peptides O-glycosylated at Thr10, the rotation of α-D-GalNAc around the linkage between the sugar and the peptide is restricted. There is evidence for a hydrogen bond between the amide proton of α-D-GalNAc and the peptide chain that could contribute to this torsional rigidity. An intramolecular hydrogen bond between the carbohydrate and the peptide chain does not exist in the peptide O-glycosylated at the Ser7 residue. Key words: conformation, contulakin-G, NMR, O-linked glycopeptide.

Determination of Polyphenolic Phytochemicals using Highly Deshielded -OH 1 H-NMR Signals

2016 ◽  
Vol 28 (3) ◽  
pp. 159-170 ◽  
Author(s):  
Pantelis Charisiadis ◽  
Vassiliki G. Kontogianni ◽  
Constantinos G. Tsiafoulis ◽  
Andreas G. Tzakos ◽  
Ioannis P. Gerothanassis
Keyword(s):  
H Nmr ◽  
Nmr Signals

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].

Hydrogen bonding, configuration and conformation of substituted α-oxo oximes and hydrazones

1979 ◽  
Vol 44 (8) ◽  
pp. 2494-2506 ◽  
Author(s):  
Otto Exner ◽  
Jorga Smolíková ◽  
Václav Jehlička ◽  
Ahmad S. Shawali
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Carbonyl Group ◽  
Intramolecular Hydrogen Bond ◽  
Benzene Solution ◽  
Dipole Moments ◽  
H Nmr ◽  
Intramolecular Hydrogen ◽  
Derivatives Of ◽  
Configuration And Conformation

Substituted 2-bromo-1-phenylglyoxal 2-phenylhydrazones IIIa-f exist in tetrachloromethane or benzene solutions prevailingly in E-configuration and in conformation A with an intramolecular hydrogen bond. The latter was evidenced by the N-H valence frequency at 3 290 cm-1 and by 1H NMR shifts with reference to derivatives without a carbonyl group - α-chlorobenzaldehyde phenylhydrazones V. From dipole moments of IIIa-d, measured in benzene solution, the contribution of the hydrogen bond (μH) was evaluated to 17 . 10-30 C m. This quantity is twice larger than in any other reported compound but the direction of the vector is as usual: approximately from H to N. In structurally similar derivatives of hydroxylamine, substituted 2-phenylglyoxylhydroximoyl chlorides IVa-d, no intramolecular hydrogen bond was detected; the dipole moments found were interpreted in terms of the Z-configuration and the prevailing conformation G.

Revision of the structure of 3-methoxy-14α-hydroxy-D-homo-1,3,5-(10)-estratrien-17a-one. A simple 1H NMR method for the determination of configuration of hydroxy group in position 5 and/or 14 of the D-homo-steroid skeleton

1991 ◽  
Vol 56 (7) ◽  
pp. 1512-1524 ◽  
Author(s):  
Miloš Buděšínský ◽  
Alexander Kasal ◽  
Želimír Procházka ◽  
Huynh Kim Thoa ◽  
Soňa Vašíčková ◽  
...  
Keyword(s):  
Hydroxy Group ◽  
Chemical Shifts ◽  
Cotton Effect ◽  
Hydroxyl Group ◽  
H Nmr ◽  
Nmr Method ◽  
Synthetic Models ◽  
Steroid Skeleton

Eignerova and Prochazka found in 1974 the Cotton effect value for 3-methoxy-14α-hydroxy-D-homo-1,3,5(10)-estratrien-17a-one (Ia) to be Δε – 2.76.Calculation of the Δε value for this compound led, however, to a substantially lower value, which suggested the hypothesis that the compound was in fact rather an epimer with the hydroxy group in position 14β. This hypothesis was studied by means of 1H NMR spectra of synthetic models, using the changes of the chemical shifts of angular methyls, induced by in situ acylation of the angular hydroxyl with an α- or β-configuration with trichloroacetyl isocyanate (TAI). The observed TAI-acylation shifts on model compounds indicated the structure Ib with a 14b-configuration of the hydroxyl group. Indenpendent proof has been given by the synthesis of both 14-hydroxy epimers, Ia and Ib. A simple 1H NMR method is proposed for the determination of configuration of the hydroxyl in position 5 or 14 of D-homo-steroid skeleton.

Addition of the nitroxyl radical TEMPO to 1-naphthylketene: formation of an unusual adduct

1999 ◽  
Vol 77 (5-6) ◽  
pp. 806-809 ◽  
Author(s):  
Jennifer Carter ◽  
Michael H Fenwick ◽  
Wen-wei Huang ◽  
Vladimir V Popik ◽  
Thomas T Tidwell
Keyword(s):  
Nitroxyl Radical ◽  
Chemical Shifts ◽  
Wolff Rearrangement ◽  
Nmr Spectrum ◽  
X Ray ◽  
H Nmr ◽  
Naphthyl Ring ◽  
Nmr Signals ◽  
Very High

1-Naphthylketene (2), generated by thermal Wolff-rearrangement, is trapped in situ by 2,2,6,6-tetramethylpiridinyloxy radical (TEMPO, TO·) to form the adduct 1-naphthCH(OT)CO2T (4), whose structure is confirmed by an X-ray determination. The 1H NMR spectrum of 4 displays three CH3 groups with very high field chemical shifts (δ 0.10-0.47), and this is attributed to the location of these groups in the shielding region above the π system of the naphthyl ring. At -40°C, doubling of most of the 1H NMR signals occurs, and this is attributed to a freezing out of two conformations differing by rotation around the naphthyl—CH bond.Key words: ketene, TEMPO, restricted rotation, 1H NMR, conformational analysis, free radicals.

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