13C NMR spectroscopy of polycyclic aromatics. V. The 13C NMR spectra of mono- and dihalonaphthalenes

1975 ◽  
Vol 20 (3) ◽  
pp. 544-553 ◽  
Author(s):  
Ludger Ernst
Keyword(s):  
Nmr Spectroscopy ◽  
13C Nmr ◽  
Nmr Spectra ◽  
13C Nmr Spectroscopy ◽  
13C Nmr Spectra ◽  
Polycyclic Aromatics

Sequence Distribution of cis-1,4- and trans-1,4-Units in Polyisoprenes

1976 ◽  
Vol 49 (5) ◽  
pp. 1269-1275
Author(s):  
Y. Tanaka ◽  
H. Sato
Keyword(s):  
Nmr Spectroscopy ◽  
13C Nmr ◽  
Nmr Spectra ◽  
13C Nmr Spectroscopy ◽  
13C Nmr Spectra ◽  
Sequence Distribution ◽  
Isomeric Structures ◽  
Nmr Signals

Abstract Recently 13C NMR spectroscopy has been successfully applied to investigate the sequence distribution of 1,2- and 1,4-units or cis-1,4- and trans-1,4-units in polybutadienes. As for polyisoprenes, however, few investigations have been made on the sequence distribution of isomeric structures using this technique, although Duch and Grant have assigned the 13C NMR signals of cis-1,4- and trans-l,4-homopolyisoprenes. In previous work we have found new signals attributed to cis-trans linkages in the 13C NMR spectra of cis-trans isomerized polyisoprenes and assigned the signals using diad sequences of cis-1,4- and trans-l,4-units. We have also studied the 13C NMR spectra of hydrogenated polyisoprenes containing various amounts of 1,4- and 3,4-units and the sequence distribution of 1,4- and 3,4-units were discussed for n-BuLi-catalyzed polyisoprenes. In this work we have investigated the sequence distribution of chicle polyisoprene and cis-trans isomerized 1,4-polyisoprenes containing various ratios of cis-1,4- and trans-1,4-units.

Synthesis of Phosphatidylcholines Possessing Functionalized Acids at sn-2, and 13C–14N and 13C–31P Couplings in Their 13C NMR Spectra

Synlett ◽  
2020 ◽  
Vol 31 (07) ◽  
pp. 718-722
Author(s):  
Masao Morita ◽  
Shun Saito ◽  
Riku Shinohara ◽  
Ryohei Aoyagi ◽  
Makoto Arita ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
13C Nmr ◽  
Nmr Spectra ◽  
13C Nmr Spectroscopy ◽  
13C Nmr Spectra ◽  
Epoxy Acids ◽  
Acid Acid ◽  
Standard Base ◽  
Acid Labile

Although 4-Me2NC5H4N (DMAP) is a standard base for esterification of (2-Me-6-NO2-C6H3CO)2O (MNBA), N-methylimidazole (NMI) was examined for the condensation of acids with 1-stearoyl-lysophosphatidylcholine because of the non-tailing nature of NMI on silica gel. Acids tested were EPA, α-linolenic acid, TBS ethers of 18-HEPE and ricinoleic acid, acid-labile epoxy acids, and a phenyldiynyl acid. The condensation proceeded well with these acids, and chromatographic separation of resulting phosphatidylcholines and remaining NMI was easily performed. During the characterization of the products by 13C NMR spectroscopy, 13C–14N and 13C–31P couplings were observed.

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.

scholarly journals Assessment of the triacylglycerol fraction of olive oil by 1D-NMR spectroscopy: exploring the usefulness of DEPT tool on the peak assignments of 13C NMR spectra

2019 ◽  
Vol 245 (11) ◽  
pp. 2479-2488
Author(s):  
Raquel Garcia ◽  
Arona Pires ◽  
Nuno Martins ◽  
Teresa Carvalho ◽  
Anthony J. Burke ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Olive Oil ◽  
13C Nmr ◽  
Nmr Spectra ◽  
13C Nmr Spectra ◽  
Triacylglycerol Fraction

13C-NMR-Spektroskopie an polycyclischen Aromaten, II. Die 13C-NMR-Spektren von 1- und 2-Fluornaphthalin. Überprüfung der Signalzuordnung und Untersuchung der Substituenteneffekte auf die chemischen Verschiebungen / 13C NMR Spectroscopy of Polycyclic Aromatics, II. The 13C NMR Spectra of 1- and 2-Fluoronaphthalene. Reexamination of Signal Assignments and Investigation of Substituent Effects on Chemical Shifts

1975 ◽  
Vol 30 (9-10) ◽  
pp. 788-793 ◽  
Author(s):  
Ludger Ernst
Keyword(s):  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Double Resonance ◽  
Substituent Effects ◽  
13C Nmr Spectroscopy ◽  
Polycyclic Aromatics ◽  
H Nmr ◽  
Iterative Analysis ◽  
C Nmr

During a reinvestigation of the 13C NMR spectra of 1-fluoronaphthalene (1) and of 2-fluoronaphthalene (2) at 20 and 25.16 MHz, uncertainties that existed in the literature about signal assignments for 1 could be cleared. In the spectral analyses for 2 given so far, five out of ten signals were incorrectly assigned. The corrected assignment is supported by extensive 13C{1H} double resonance experiments, by recording of proton-coupled 13C and 13C{19F} spectra and by off-resonance 13C{1H} noise-decoupling. The results show a strong + M-effect of the fluorine substituents on 13C chemical shifts similar to the effects of OH and OCH3 groups. 1H NMR spectra of 1 and 2 could be partially assigned by decoupling of the 19F resonances and by iterative analysis.

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.

scholarly journals Qualitative and Quantitative Analysis of Heavy Crude Oil Samples and Their SARA Fractions with 13C Nuclear Magnetic Resonance

Processes ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 995
Author(s):  
Ilfat Rakhmatullin ◽  
Sergey Efimov ◽  
Vladimir Tyurin ◽  
Marat Gafurov ◽  
Ameen Al-Muntaser ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nmr Spectroscopy ◽  
Magnetic Resonance ◽  
Crude Oil ◽  
Functional Groups ◽  
13C Nmr ◽  
Nmr Spectra ◽  
13C Nmr Spectra ◽  
Sara Fractions ◽  
Nuclear Magnetic

Nuclear magnetic resonance (NMR) approaches have unique advantages in the analysis of crude oil because they are non-destructive and provide information on chemical functional groups. Nevertheless, the correctness and effectiveness of NMR techniques for determining saturates, aromatics, resins, and asphaltenes (SARA analysis) without oil fractioning are still not clear. In this work we compared the measurements and analysis of high-resolution 13C NMR spectra in B0 ≈ 16.5 T (NMR frequency of 175 MHz) with the results of SARA fractioning for four various heavy oil samples with viscosities ranging from 100 to 50,000 mPa·s. The presence of all major hydrocarbon components both in crude oil and in each of its fractions was established quantitatively using NMR spectroscopy. Contribution of SARA fractions in the aliphatic (10–60 ppm) and aromatic (110–160 ppm) areas of the 13C NMR spectra were identified. Quantitative fractions of aromatic molecules and oil functional groups were determined. Aromaticity factor and the mean length of the hydrocarbon chain were estimated. The obtained results show the feasibility of 13C NMR spectroscopy for the express analysis of oil from physical properties to the composition of functional groups to follow oil treatment processes.

Sign in / Sign up

Export Citation Format

Share Document