Hochauflösungs-13C-NMR-Spektroskopie, VI [1]. Strukturabhängigkeit der 13C,H-Kopplungskonstanten in 6.6-disubstituierten Fulvenen / High Resolution 13C NMR Spectroscopy, VI [1]. Structure Dependence of the 13C,H Coupling Constants in 6,6-Disubstituted Fulvenes

1980 ◽  
Vol 35 (12) ◽  
pp. 1572-1574 ◽  
Author(s):  
Siegmar Braun ◽  
Ulrich Eiehenauer
Keyword(s):  
Nmr Spectroscopy ◽  
13C Nmr ◽  
Nmr Spectra ◽  
13C Nmr Spectroscopy ◽  
High Accuracy ◽  
Coupling Constants ◽  
Complete Analysis ◽  
Structure Parameters ◽  
Structure Dependence ◽  
C Nmr

In order to study the structure dependence of the 13C,H couplings in the fulvene system the 1H-coupled 13C NMR spectra of 6,6-disubstituted fulvenes (R = R′ = C6H5, CH3, cyclopropyl and N(CH3)2) were recorded and the interesting couplings determined with high accuracy by complete analysis. They have values typical for unsaturated five membered rings with vastly localised double bonds like cyclopentadiene-1,3 and spiro[2.4]heptadiene- 4,6 and show characteristic correlations with structure parameters.

Organoboranes and tetraorganoborates studied by 11B and 13C NMR spectroscopy and DFT calculations

2015 ◽  
Vol 70 (6) ◽  
pp. 421-424 ◽  
Author(s):  
Bernd Wrackmeyer
Keyword(s):  
Nmr Spectroscopy ◽  
Dft Calculations ◽  
13C Nmr ◽  
Quantum Chemical ◽  
13C Nmr Spectroscopy ◽  
Coupling Constants ◽  
Line Widths ◽  
Nmr Signals ◽  
C Nmr ◽  
Extract Information

AbstractCare should be taken on recording the sometimes elusive 13C NMR signals for boron-bonded carbon atoms, since it is easy to extract information about coupling constants 1J(13C,11B) by measuring the respective line widths of 13C(B-C) and 11B NMR signals. This information can be confirmed by quantum-chemical calculations [B3LYP (6-311+G(d,p) level of theory] of nJ(13C,11B) in organoboranes and tetraorganoborates. For the latter, the signs for n = 2, 3, 4 were experimentally determined.

Substituent Influences on the Keto-Enol Tautomerism in 1-(2-Hydroxyphenyl)-3-α-and -β-naphthylpropane-1,3-diones Monitored by 1H and 13C NMR Spectroscopy

2000 ◽  
Vol 55 (2) ◽  
pp. 193-202 ◽  
Author(s):  
Jorge L. Jios ◽  
Helmut Duddeck
Keyword(s):  
Nmr Spectroscopy ◽  
Long Range ◽  
13C Nmr ◽  
Nmr Spectra ◽  
13C Nmr Spectroscopy ◽  
1H And 13C Nmr ◽  
Tautomeric Equilibria ◽  
Hmbc Correlation ◽  
C Nmr

Synthesis of 18 1-(2-hydroxyphenyl)-3-α- and -β-naphthylpropan-1,3-diones is described. Their 1H and 13C NMR spectra were completely and unambiguously assigned using a combination of both homo- and heteronuclear (gs-COSY ), 1H -detected heteronuclear one-bond (gs-HMQC ) and long-range (gs-HMBC) correlation experiments. Substituent and conformation effects on the tautomeric equilibria were identified and interpreted in terms of steric and electronic contributions.

Chemistry of chromotropic acid. 1H and 13C NMR spectroscopy of chromotropic acid and its derivatives

1991 ◽  
Vol 69 (8) ◽  
pp. 1207-1211 ◽  
Author(s):  
Paris E. Georghiou ◽  
Chi Keung (Jimmy) Ho ◽  
Chester R. Jablonski
Keyword(s):  
Nmr Spectroscopy ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Deuterium Oxide ◽  
13C Nmr Spectroscopy ◽  
Chromotropic Acid ◽  
Hydroxyl Groups ◽  
Two Dimensional ◽  
1H And 13C Nmr ◽  
C Nmr

The 1H and 13C NMR spectra of chromotropic acid (CTA) (4,5-dihydroxy-2,7-naphthalenedisulphonic acid) have been unambiguously assigned. Proton NOED spectra were used to show the proximity of both H-3 and H-6 and the hydroxyl groups. Two-dimensional 1H–13C NMR correlation spectra of CTA, of its corresponding diacetoxy derivative, and of 3-bromo- and 3,6-dibromo-CTA support the assignments. A regioselective deuterium exchange reaction of the C-3 and C-6 protons of CTA with deuterium oxide was observed during the NMR experiments. This latter finding is strongly indicative of the mode of formation, and of the nature of the chromogen formed in the reaction of CTA with formaldehyde in the well-known CTA-formaldehyde analytical reaction. Key words: chromotropic acid, 3-bromochromotropic acid, 3,6-dibromochromotropic acid.

11B- und 13C-NMR-Spektroskopie von nido-Hexaalkyl-2.3.4.5-tetracarbahexaboranen(6) / 11B- und 13C-NMR Spectroscopy of nido-Hexaalkyl-2,3,4,5-tetracarbahexaboranes(6)

1982 ◽  
Vol 37 (4) ◽  
pp. 412-419 ◽  
Author(s):  
Bernd Wrackmeyer
Keyword(s):  
Nmr Spectroscopy ◽  
13C Nmr ◽  
13C Nmr Spectroscopy ◽  
Coupling Constants ◽  
Triple Resonance ◽  
Triple Resonance Experiments ◽  
Nmr Data ◽  
Nuclear Shielding ◽  
C Nmr

11B and 13C NMR data of peralkylated nido-2,3,4,5-tetracarbahexaboranes(6) are reported. Application of selective heteronuclear triple resonance experiments 13C{1H,11B} enables to assign the structures of various isomers. The magnitude of the coupling constants 1J(11B11B), 1J(13C11B) and 1J(13C13C) is in accord with expectations based on the conception of bonding in carboranes. The comparison of δ11B and δ13C data of the nido- 2,3,4,5-tetracarboranes(6) with δ13C-data of corresponding non-classical carbocations shows the influence of charge upon the nuclear shielding of carbon in the latter.

Structure of condensation products between isonicotinylhydrazine and reducing sugars by 13C nmr spectroscopy

1981 ◽  
Vol 59 (3) ◽  
pp. 641-646 ◽  
Author(s):  
Keith Bailey ◽  
Andrew G. Butterfield
Keyword(s):  
Nmr Spectroscopy ◽  
13C Nmr ◽  
Spectroscopic Data ◽  
Nmr Spectra ◽  
Reducing Sugars ◽  
13C Nmr Spectroscopy ◽  
Condensation Products ◽  
C Nmr

The structures of the condensation products of isonicotinylhydrazine (isoniazid) with galactose, glucose, lactose, maltose, glycolaldehyde and glyceraldehyde were investigated by examination of their 13C nmr spectra, determined in D2O and DMSO-d6 solution. Spectroscopic data and their interpretation are presented. Spectroscopic and chromatographic (hplc) evidence are combined to show that the products formed with the four sugars exist in solution predominantly as l-(1β-pyranosyl)-2-isonicotinylhydrazines, and to a lesser extent as the analogous 1α-pyranosyl anomers. The products formed with glycolaldehyde and glyceraldehyde are normal hydrazones.

A Novel Method for 13C-NMR Spectroscopy of Polymer in Emulsion: Quantitative Analysis of Microstructure of Crosslinked Polybutadiene in Latex

1999 ◽  
Vol 72 (5) ◽  
pp. 844-853 ◽  
Author(s):  
Seiichi Kawahara ◽  
Saori Bushimata ◽  
Takashi Sugiyama ◽  
Chihiro Hashimoto ◽  
Yasuyuki Tanaka
Keyword(s):  
Nmr Spectroscopy ◽  
High Resolution ◽  
13C Nmr ◽  
Lattice Relaxation ◽  
13C Nmr Spectroscopy ◽  
Lattice Relaxation Time ◽  
Solid Sample ◽  
Spin Lattice Relaxation ◽  
High Resolution Spectrum ◽  
C Nmr

Abstract A novel analytical method using high resolution 13C-NMR spectroscopy to study polymer latex, which is a heterogeneous system comprising polymer dispersoid and water, is described. The appropriate concentrations of surfactant and dried rubber content of a polybutadiene latex, which give the best spectrum, were found to be 1 w/v % and 10%, respectively. The half-widths of resonance peaks for the latex sample were almost identical to the half-widths obtained in solution, which were about one-third the width of those obtained using a solid sample of either a crosslinked or soluble polybutadiene. Nevertheless, the signal to noise ratio for the latex sample was slightly smaller than that for the solution sample. The values of spin-lattice relaxation time, T1, for the latex sample were similar to those for the solid sample. These demonstrate that the latex state C-NMR spectroscopy will be a powerful technique for structural characterization of crosslinked gels in the dispersoid because it gives a high resolution spectrum comparable to solution state spectroscopy, showing short T1 values corresponding to those for solid state C-NMR spectroscopy. High resolution latex state 13C-NMR spectroscopy was used to determine the concentrations of the various isomers of the polybutadiene in the dispersoid.

Structural studies of digitoxin and related cardenolides by two-dimensional NMR

1990 ◽  
Vol 68 (2) ◽  
pp. 272-277 ◽  
Author(s):  
Torbjörn Drakenberg ◽  
Peter Brodelius ◽  
Deane D. McIntyre ◽  
Hans J Vogel
Keyword(s):  
Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Chair Conformation ◽  
Coupling Constants ◽  
Two Dimensional ◽  
Structural Studies ◽  
Solution Conformation ◽  
Phase Sensitive ◽  
Multiple Relay ◽  
C Nmr

The 1H and 13C NMR spectra of the cardenolides digitoxigenin, digoxigenin, digitoxin, and mono- and bis-digitoxigenin digitoxosides have been completely assigned by two-dimensional NMR spectroscopy. The techniques used include phase-sensitive COSY, multiple relay COSY, and carbon–proton correlation (HETCOR and HMQC) spectra. Various aspects of the solution conformation of the steroid moiety of digitoxin and digoxigenin could be determined from coupling constants and NOE difference experiments and they are indicative of an all-chair conformation. The carbohydrate rings in digitoxin and the mono- and bis-digitoxigenin digitoxosides are also in the chair conformation. Keywords: cardenolides, digitoxigenin, digitoxin, 2-dimensional NMR, conformational analysis.

13C-NMR-Spektroskopie an polycyclischen Aromaten, IIΙ Die 13C-NMR-Spektren von Amino- und Dimethylaminonaphthalinen /13C NMR Spectroscopy of Polycyclic Aromatics, III The 13C NMR Spectra of Amino- and Dimethylaminonaphthalenes

1975 ◽  
Vol 30 (9-10) ◽  
pp. 794-799 ◽  
Author(s):  
Ludger Ernst
Keyword(s):  
13C Nmr ◽  
High Field ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Double Resonance ◽  
Substituent Effects ◽  
13C Nmr Spectroscopy ◽  
Polycyclic Aromatics ◽  
Electrophilic Reagents ◽  
C Nmr

The 13C NMR spectra of twelve amino-, dimethylamino-, diamino-, and bis(dimethylamino)naphthalenes are completely assigned by selective 13C{1H} double resonance and by interpretation of proton-coupled spectra. Strong substituent effects (Δδ) upon chemical shifts are observed and can largely be accounted for by mesomerism. The pronounced high-field shifts of C-6 in the 2-amino- and 2-dimethylaminonaphthalenes coincide with the enhanced reactivity of this position towards electrophilic reagents. In 1-dimethylaminonaphthalene and even more so in 1-dimethylamino-2-methylnaphthalene, conjugation is inhibited for steric reasons and Δδ’s are greatly diminished, thus giving an estimate for the contribution of resonance to substituent-induced shifts in the unhindered compounds. In two 1,8-disubstituted naphthalenes there are large deviations from additivity of substituent effects.

Notizen: 13C-NMR an paramagnetischen Phenylmetallocenen1: Analogie zum Benzylradikal.

1976 ◽  
Vol 31 (8) ◽  
pp. 1153-1154 ◽  
Author(s):  
Frank H. Köhler ◽  
G. Matsubayashi
Keyword(s):  
Density Distribution ◽  
Spin Density ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Hyperfine Coupling ◽  
Spin Density Distribution ◽  
Coupling Constants ◽  
Methyl Radicals ◽  
Benzyl Radical ◽  
C Nmr

The 13C NMR spectra of seven phenylated paramagnetic metallocenes have been recorded. From the spectra the 13C hyperfine coupling constants A(13C) have been extracted and compared with corresponding A(1H). It is found that the phenyl A′s in nickelocenes and cobaltocenes behave as in benzyl radical being reduced by a factor of 27. This offers a new route to informations about spin density distribution in substituted methyl radicals.

Extent of intramolecular cyclization in RAFT-synthesized methacrylic branched copolymers using 13C NMR spectroscopy

2015 ◽  
Vol 6 (7) ◽  
pp. 1143-1149 ◽  
Author(s):  
J. Rosselgong ◽  
S. P. Armes
Keyword(s):  
Nmr Spectroscopy ◽  
Intramolecular Cyclization ◽  
13C Nmr ◽  
13C Nmr Spectroscopy ◽  
Branched Copolymers ◽  
C Nmr

The extent of intramolecular cyclization for a series of soluble branched methacrylic copolymers is determined by 13C NMR spectroscopy via deconvolution of oxymethylene carbon signals.

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