ISSN:0030-4921    

DOI:10.1002/mrc.1270061115

出版商:John Wiley&Sons Limited    

年代:1974

数据来源: WILEY

摘要:

AbstractThe19F and31P NMR spectral parameters of a series ofmetaandparasubstituted phenylphosphonic difluorides were found to be linearly related to the substituent parameters: the phosphorus chemical shifts correlated with Hammett's σ constant, the fluorine chemical shifts with Taft's σRparameter and the phosphorus–fluorine coupling constants with

ISSN:0030-4921    

DOI:10.1002/mrc.1270061102

出版商:John Wiley&Sons Limited    

年代:1974

数据来源: WILEY

摘要:

AbstractAn Dreiding‐Modellen der verschiedenen Konformere von 1,3‐Aza‐ und 1,3‐Oxaphospholanen werden die GeometriefaktorenG[G= (cos2θ – 1)r−3] einzelner Protonen bezüglich eines Koordinationszentrums [Eu(dpm)3] bestimmt. Das Koordinationszentrum wird entweder an dem Sauerstoff der Carbonylgruppe oder an dem Stickstoff oder Sauerstoff im Heteroring gebunden angenommen. Die graphische Darstellung der Geometriefaktoren gegen die paramagnetischen Verschiebungen der betreffenden Protonen ergibt nur für die bevorzugten Konformere bei Zugrundelegung der richtigen Koordinationszentren Geraden. Als Maßzahl für die paramagnetische Verschiebung eines Protons wird die Steigung der Geraden gewählt, die sich beim graphischen Auftragen der chemischen Verschiebung gegen den Gehalt an Eu(dpm)3(in Mol‐%) ergibt. Durch Variation der relativen Konfiguration am C‐Atom 5 an den Modellen und Berechnung der Geometriefaktoren ist es möglich, die unterschiedlichen Diastereomere zuzuordnen, die sich bezüglich der Substituentenstellung am Phosphor und am

ISSN:0030-4921    

DOI:10.1002/mrc.1270061103

出版商:John Wiley&Sons Limited    

年代:1974

数据来源: WILEY

摘要:

AbstractThe proton exchange reaction between the indenyl carbanion and its parent compound indene has been studied by NMR as a function of temperature. The rate of this bimolecular reaction is very low and has been found to be strongly dependent on the polarity of the solvent. In solvents like dimethoxyethane (ϵ = 7·2) and diglyme the reaction becomes manifest in the NMR spectrum only at elevated temperatures (T>150°C). In hexamethylphosphortriamide (ϵ = 30) the rate is much greater and line broadening may be observable at room temperature. The reaction in this solvent is characterised by a frequency factorf= 7 × 1071 mol−1s−1, an activation enthalpy ΔH≠ = 9·5 kcal mol−1and an entropy of activation ΔS≠ = −23 e.u. The low reaction rate and its solvent dependence ar

ISSN:0030-4921    

DOI:10.1002/mrc.1270061104

出版商:John Wiley&Sons Limited    

年代:1974

数据来源: WILEY

摘要:

AbstractAn analysis of both the aromatic and aliphatic portions of the1H NMR spectrum of α‐tetralone has been carried out. Two deuterated derivatives, 2,2‐dideuterio‐ and 4,4‐dideuterio‐α‐tetralone, were prepared to facilitate unambiguous assignment of chemical shifts for the aliphatic protons. The conformation of the 6‐membered alicyclic ring of the molecule is defined by the coupling constants among the aliphatic protons. Benzylic coupling was the only detectable long range interaction between the aliphatic and aromatic protons of the molecule. The magnitude and sign of these coupling constants agree with previous calculations of Wasylish

ISSN:0030-4921    

DOI:10.1002/mrc.1270061105

出版商:John Wiley&Sons Limited    

年代:1974

数据来源: WILEY

摘要:

AbstractCarbon‐13 chemical shifts of three arylmethyl carbanions have been determined by changing solvents and counter ions. The charge distributions in the carbanions are discussed and compared with those obtained from the1H chemical shift

ISSN:0030-4921    

DOI:10.1002/mrc.1270061106

出版商:John Wiley&Sons Limited    

年代:1974

数据来源: WILEY

摘要:

AbstractCarbon‐13 NMR spectra have been obtained and analyzed for a series of saturated linear and cyclic sulfur‐containing organic molecules. For the large cyclic polythiaethers whose proton spectra are broad and unresolved, it is found that carbon‐13 spectra are sharp and well resolved. The resonances of all carbons fall within the expected chemical shift ranges. Based upon the comparative resolution in the spectra of large and small cyclic species, it is concluded that whatever conformational motion may exist within the rings must be occurring very rapidly on the NMR time

ISSN:0030-4921    

DOI:10.1002/mrc.1270061107

出版商:John Wiley&Sons Limited    

年代:1974

数据来源: WILEY

摘要:

Abstract13C NMR spectra of unsubstituted 1,6,6aλ4‐trithiapentalene and a series of methyl and phenyl substituted 1,6,6aλ4‐trithiapentalenes have been recorded. The spectra have been assigned by comparison with1H NMR data based on coupling constants from undecoupled spectra. From the chemical shift of C‐3a it is concluded that the double bond character of the C‐3a—S‐6a is low. The relaxation times for C‐2 and C‐3 only show small differences; this seems not to be in favour of a fast interconversion between two thiocarbonyl forms. The NMR data obtained seem thus to be in accordance with a bicyclic naphthalene‐like structure with ten delo

ISSN:0030-4921    

DOI:10.1002/mrc.1270061108

出版商:John Wiley&Sons Limited    

年代:1974

数据来源: WILEY

摘要:

AbstractThe synthesis of a D/Ecisisomer of the title compound is described. In an attempt to obtain the other D/Ecisisomer, epimerisation reactions were studied. The configuration and conformation of the isomers are determined on the basis of their1H NMR spectra. The shift of the 16b proton on N‐9 protonation indicates the quinolizidine conformation. At 270 MHz, the ABCD system of the C‐10 and C‐11 methylenes can be analysed. The2J(C‐10H2), together with the multiplicity of H‐8a, allows an unequivocal assignment of acis‐anti‐cisstructure to the only D/Ecisis

ISSN:0030-4921    

DOI:10.1002/mrc.1270061109

出版商:John Wiley&Sons Limited    

年代:1974

数据来源: WILEY

摘要:

AbstractThe1H NMR spectra of thirteen dihydro‐1,2‐oxazine derivatives are reported. Spin decoupling allows analysis of the spectra, features of which include homoallylic couplings of +2 to +2·5 Hz, allylic couplings of −1·5 to −1·7 Hz and vicinal couplings acrosssp2tosp3carbon–carbon bonds of +2

ISSN:0030-4921    

DOI:10.1002/mrc.1270061110

出版商:John Wiley&Sons Limited    

年代:1974

数据来源: WILEY