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.

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 13C-NMR-Spektroskopie an polycyclischen Aromaten, IV Das 13C-NMR-Spektrum von 1-Aminopyren / 13C NMR Spectroscopy of Polycyclic Aromatics, IV The 13C NMR Spectrum of 1-Aminopyrene

1975 ◽  
Vol 30 (9-10) ◽  
pp. 800-803 ◽  
Author(s):  
Ludger Ernst
Keyword(s):  
Nmr Spectroscopy ◽  
13C Nmr ◽  
High Field ◽  
Chemical Shifts ◽  
Double Resonance ◽  
Substituent Effects ◽  
13C Nmr Spectroscopy ◽  
Polycyclic Aromatics ◽  
Nmr Spectrum ◽  
C Nmr

In the 13C NMR spectrum of ] -aminopyrene (1) in [D6] acetone all carbon atoms are anisochronous. Most of the sixteen signals can be safely assigned by selective 13C{1H}double resonance experiments and by the interpretation of proton-coupled 13C as well as with the aid of off-resonance noise-decoupled 13C{1H} spectra. Substituent effects on chemical shifts in rings A, B, and D are compared with those of the 1- and 2-aminonaphthalenes (2, 3). Even in ring C, most distant from the substituent, relatively strong high-field shifts are observed which are ascribed to mesomerism.

Synthetic and 1H and 13C NMRSpectral Studies on N-(Mono-substitutedphenyl)- acetamides and Substituted Acetamides, 2/3/4-YC6H4NH-COCH3–iXi (Y = CH3, F, Cl, Br, NO2; X = Cl, CH3; i = 0, 1, 2, 3)

2006 ◽  
Vol 61 (10-11) ◽  
pp. 595-599
Author(s):  
Basavalinganadoddy Thimme Gowda ◽  
Shilpa Lakshmipathy ◽  
Jayalakshmi K. Lakshmipathy
Keyword(s):  
Electron Density ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Nmr Chemical Shifts ◽  
H Nmr ◽  
C Nmr

Nineteen N-(2/3/4-methyl/halo/nitro-phenyl)-acetamides and substituted acetamides, 2/3/4- YC6H4NH-CO-CH3−iXi (Y = CH3, F, Cl, Br or NO2; X = Cl or CH3 and i = 0, 1, 2 or 3), have been prepared, characterized, and their 1H and 13C NMR spectra in solution measured and correlated. 1H and 13C NMR chemical shifts were assigned to the protons and carbon atoms, respectively, in line with those for similar compounds. Since the chemical shifts are dependent on the electron density around the nucleus or associated with the atom to which it is bound, the incremental shifts of the aromatic protons or carbon atoms due to -NH-CO-CH3−iXi and -CO-CH3−iXi (X = Cl or CH3 and i = 0, 1, 2, 3) in all the N-phenyl-substituted acetamides, C6H5NH-CO-CH3−iXi, are calculated by comparing the proton or carbon chemical shifts of these compounds with those of benzene or aniline. The incremental shifts due to the groups in the parent compounds have also been computed by comparing the chemical shifts of the protons or carbon atoms in these compounds with those of benzene or aniline, respectively. The computed incremental shifts and other data were used to calculate the 1H and 13C NMR chemical shifts of the substituted compounds in three different ways. The calculated chemical shifts by the three methods compared well with each other and with the observed chemical shifts, testing the validity of the principle of additivity of the substituent effects in these compounds. The variation of 1H NMR chemical shifts of either the aromatic or N-H protons, with the substituents in N-(phenyl)- and N-(2/3/4-chloro/methylphenyl)-acetamides and substituted acetamides did not follow the same trend, while the variation of the 13C NMR chemical shifts of C-1 and C=O carbon atoms and those of alkyl carbon atoms of these compounds followed more or less the same trend.

Carbon-13 nuclear magnetic resonance spectra of E-silyl-alkenes

1980 ◽  
Vol 58 (4) ◽  
pp. 361-368 ◽  
Author(s):  
Constantinos A. Tsipis ◽  
Constantinos A. Tsoleridis
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Quantitative Analysis ◽  
Nmr Spectroscopy ◽  
Carbon Atom ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
H Nmr ◽  
Nuclear Magnetic Resonance Spectra ◽  
C Nmr

Carbon-13 nmr chemical shifts of a number of E-silyl-alkenes containing the silyl substituent at an sp2 carbon atom are presented. Assignments of the chemical shifts have been made by noting systematic variations in the spectra with changes in substituents and by comparison of the chemical shifts to those of the corresponding unsubstituted alkenes. The substituent effects observed were explained on the basis of the π-acceptor ability of the silyl substituents and the structure of the molecules. Comparing the 13C nmr spectra of the E-silyl-alkenes and those of the corresponding unsubstituted alkenes, differential chemical shifts have been obtained which can be used as empirical substituent parameters for the prediction of the 13C nmr spectra of other E-silyl-alkenes not yet studied. It was also demonstrated that 13C nmr spectroscopy can be used without resorting to special techniques (gated decoupling and the addition of paramagnetics) as an alternative method to the 1H nmr for the quantitative analysis of mixtures of regio-isomer E-silyl-alkenes.

1H and 13C NMR study of (X-phenyl)-5-nitro-2-furylvinyl ethers

1980 ◽  
Vol 45 (12) ◽  
pp. 3557-3563 ◽  
Author(s):  
Miloslava Dandárová ◽  
Jaroslav Kováč ◽  
Daniel Végh
Keyword(s):  
Nmr Spectroscopy ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Furan Ring ◽  
Chemical Shifts ◽  
1H And 13C Nmr ◽  
H Nmr ◽  
Nmr Study ◽  
Hammett Σ Constants ◽  
C Nmr

Reaction of 5-nitro-2-furylvinyltrimethylammonium bromide with substituted phenolates gave (E)- and (Z)-(X-phenyl)-5-nitro-2-furylvinyl ethers. The preffered s-cis and s-trans orientations of the furan ring in Z and E isomers, respectively, were determined by 1H NMR spectroscopy. To study the extent of p-π conjugation, 13C NMR spectra of compounds under investigation have also been measured and interpreted. Chemical shifts for ethylenic carbons and protons were correlated with Hammett σ constants.

Hydrolyse des dérivés de cyclopropylidène-3 propyle. Structure et stéréochimie des alcools précurseurs et des produits résultant de l'hydrolyse

1981 ◽  
Vol 59 (7) ◽  
pp. 1089-1095 ◽  
Author(s):  
Robert Faure ◽  
Gilbert Leandri ◽  
Alain Meou
Keyword(s):  
Ir Spectroscopy ◽  
Nmr Spectra ◽  
Molecular Conformation ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
H Nmr ◽  
Hydrolysis Products ◽  
Hydrolysis Of ◽  
C Nmr

The 13C nmr spectra of 14 β-cyclopropylidenic alcohols 1 have been determined:[Formula: see text]All the chemical shifts were assigned and the substituent effects are discussed as a function of molecular conformation. The stereochemistry of two diastereoisomers of alcohols 1e (R1 = R3 = H; R2 = R4 = CH3) and 1k (R3 = H; R1 = R2 = R4 = CH3) was established from ir spectroscopy and 1H nmr results.The 13C nmr spectra of products arising from hydrolysis of 3-cyclopropylidene propanol 1a and 4-cyclopropylidene 2-butanol 1b tosylates have been also recorded. The analysis of these data enables us to establish unambiguously the structure and the stereochemistry of the hydrolysis products.

13C NMR spectra of 1-aryl-ferrocenylethylenes

1986 ◽  
Vol 51 (3) ◽  
pp. 670-676 ◽  
Author(s):  
Eva Solčániová ◽  
Štefan Toma ◽  
Tibor Liptaj
Keyword(s):  
13C Nmr ◽  
Nmr Spectra ◽  
Substituent Effects ◽  
13C Nmr Spectra ◽  
Bridge Group ◽  
C Nmr ◽  
Electron Effects

13C NMR spectra of 18 ferrocene analogues of trans stilbenes (1-aryl-2-ferrocenylethylenes) were measured. It was found that bridge group weakens the transfer of the substituent electron effects into ferrocene nucleus, especially distinctly into 3',4'positions of cyclopentadienyl ring. The transfer of substituent effects into β-position of the bridge -CH=CH- is greater in derivatives studied by us than in stilbenes. Synthesis of 1-(4-dimethylaminophenyl)-2-ferrocenylethylene is described.

17O and 13C NMR spectra of some geminal diacetates

1988 ◽  
Vol 53 (3) ◽  
pp. 588-592 ◽  
Author(s):  
Antonín Lyčka ◽  
Josef Jirman ◽  
Jaroslav Holeček
Keyword(s):  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
The Other ◽  
13C Nmr Spectra ◽  
Other Hand ◽  
Carboxylic Esters ◽  
C Nmr ◽  
Oxygen Atoms

The 17O and 13C NMR spectra of eight geminal diacetates RCH(O(CO)CH3)2 derived from simple aldehydes have been measured. In contrast to the dicarboxylates R1R2E(O(CO)R3)2, where E = Si, Ge, or Sn, whose 17O NMR spectra only contain a single signal, and, on the other hand, in accordance with organic carboxylic esters, the 17O NMR spectra of the compound group studied always exhibit two well-resolved signals with the chemical shifts δ(17O) in the regions of 183-219 ppm and 369-381 ppm for the oxygen atoms in the groups C-O and C=O, respectively.

Proximity and conformation effects in 29Si and 13C NMR spectra of di-ortho substituted trimethylsiloxybenzenes

1990 ◽  
Vol 55 (8) ◽  
pp. 2027-2032 ◽  
Author(s):  
Jan Schraml ◽  
Robert Brežný ◽  
Jan Čermák
Keyword(s):  
Benzene Ring ◽  
13C Nmr ◽  
Proximity Effect ◽  
Nmr Spectra ◽  
Methoxy Group ◽  
Chemical Shifts ◽  
Proximity Effects ◽  
13C Nmr Spectra ◽  
Methoxy Groups ◽  
C Nmr

29Si and 13C NMR spectra of five 4-substituted 2,6-dimethoxytrimethylsiloxybenzenes were studied with the aim to elucidate the nature of the deshielding proximity effects observed in the spectra of ortho substituted trimethylsiloxybenzenes. The sensitivity of 29Si chemical shifts to para substitution is in the studied compounds essentially the same as in mono ortho methoxytrimethylsiloxybenzenes. The deshielding proximity effect of the ìsecondî methoxy group is somewhat smaller than that of the ìfirstî group. The present results indicate that the two methoxy groups assume coplanar conformations with the benzene ring and are turned away from the trimethylsiloxy group which is not in the benzene plane. It is argued that in mono ortho methoxytrimethylsiloxybenzenes the two substituent groups adopt the same conformations as in the compounds studied here.

scholarly journals Substituenteneinflüsse auf die 13C–NMR-chemischen Verschiebungen cis- und trans-konfigurierter Trimethincyanine / Substituent Effects on the 13C NMR Chemical Shifts of Trimethincyanines with cis and trans Configuration

1976 ◽  
Vol 31 (12) ◽  
pp. 1641-1645 ◽  
Author(s):  
Walter Grahn
Keyword(s):  
13C Nmr ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Electron Systems ◽  
Coupling Constant ◽  
Electronic Effects ◽  
Nmr Chemical Shifts ◽  
Monosubstituted Benzenes ◽  
Cis And Trans ◽  
C Nmr

The 13C NMR chemical shifts of fifteen 6 substituted 2,3-dihydro-1,4-diazepinium salts (cis trimethincyanines) (1) and twelve 2 substituted bis(dimethylamino)trimethinium salts (trans trimethincyanines) (2) have been determined. A comparison of the substituentinduced shifts (13C SCS) of 1 and 2 allows no distinction between steric and electronic effects. In the three 6 п-electron systems 1, 2 and monosubstituted benzenes the 13C SCS are similar for the substituent bearing carbon atoms. A surprisingly large 4JFCCNC coupling constant has been observed.

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