摘要:

AbstractThe literature on13C n.m.r. examinations of steroids has been reviewed and the shielding data for over 400 examples are tubulated. The assignments for each compound have been considered and, where necessary, revised in the light of more recent evidence and for consistency throughout each series. The methods available for assignments are reviewed and, in many cases, illustrated with specific examples. The major practical features concerning13C studies of steroids are discussed as a guide to the use of the technique. From the main body of shielding data, an extensive set of substituent effects has been generated to aid the examination of new systems. The utility and the limitations of these effects are described.

ISSN:0030-4921    

DOI:10.1002/mrc.1270090802

出版商:John Wiley&Sons Limited    

年代:1977

数据来源: WILEY

摘要:

AbstractDurch elektrolytische Oxidation konnten aus dinuklearen Polymethincyanin‐Farbstoffen Dikation‐Radikale erzeugt werden. Ihre ESR‐Spektren bestätigen die erwartete Struktur der Ra

ISSN:0030-4921    

DOI:10.1002/mrc.1270090803

出版商:John Wiley&Sons Limited    

年代:1977

数据来源: WILEY

摘要:

AbstractThe preferred conformations of the four isomers of 1,2,3,4,4a,6,7,8,9,13b‐decahydro‐9aH‐pyrido[1,2‐f] phenanthridine have been determined by 270 MHz1H n.m.r. and i.r. spectroscopy. N.m.r. assignments are based on the specific chemical shifts of the protons adjacent to the nitrogen atom, their geminal coupling constants and on the shifts induced by the CC bonds and by the benzene nucleus. Specifically deuterated derivatives and double resonance experiments confirm the assignments unequivocally. These data are completed by solvent and temperatur

ISSN:0030-4921    

DOI:10.1002/mrc.1270090804

出版商:John Wiley&Sons Limited    

年代:1977

数据来源: WILEY

摘要:

AbstractCarbon‐13, proton coupling constants have been measured in eighteen different 2‐substituted propanes.1J(C‐2,H) shows variations similar to those observed previously for monosubstituted methanes.2J(C‐2,H) is essentially independent of the substituent at C‐2, while2J(C‐1,H) varies over a range of at least 5 Hz. The latter coupling constant becomes more positive as the electronegativity of the substituent increases while3J(CH) decreases as the electronegativity of the substituent increases. The observed trends innJ(CH) are compared with those calculated using semi‐empirical molecular orbital theory at the INDO level of

ISSN:0030-4921    

DOI:10.1002/mrc.1270090805

出版商:John Wiley&Sons Limited    

年代:1977

数据来源: WILEY

摘要:

AbstractINDO calculations are reported of the13C nuclear screening tensors in coumarin and some of its methoxy derivatives. Calculations based upon a linear combination of gauge dependent atomic orbitals and those using an uncoupled Hartree–Fock approach are described. Comparison with the results of less sophisticated calculations shows that changes in the excitation energies, bond orders and the 〈r−3〉2pterm are together responsible for determining the13C chemical

ISSN:0030-4921    

DOI:10.1002/mrc.1270090806

出版商:John Wiley&Sons Limited    

年代:1977

数据来源: WILEY

摘要:

AbstractAnalysis of the Vorontsova calculation of vicinal coupling constants in terms of angular and chemical shift dependence indicates some serious inconsistencies in this equation.

ISSN:0030-4921    

DOI:10.1002/mrc.1270090807

出版商:John Wiley&Sons Limited    

年代:1977

数据来源: WILEY

摘要:

AbstractFull analyses of the five‐spin1H n.m.r. spectra for the diene protons of isoprene, ethylbutadiene and β‐myrcene under conditions of decoupling the sidechain α‐protons are reported. The data are discussed in terms of spin–spin coupling mechanism and molecular conformation. The fully‐coupled spectra of the compounds were also examined and coupling informati

ISSN:0030-4921    

DOI:10.1002/mrc.1270090808

出版商:John Wiley&Sons Limited    

年代:1977

数据来源: WILEY

摘要:

AbstractThe hydroxyl proton chemical shifts oftert‐butyl alcohol, dissolved in acetone and in binary mixtures of acetone with cyclohexane, have been measured as functions of concentration at temperatures of 20, 35, 50 and 60 °C. Using both the equilibrium constant and the quasi‐lattice methods for the interpretation of experimental data, the thermodynamic parameters of self‐association and complexation have been determined, and their dependences on the solvent composition have been analysed. The chemical shifts of the hydroxyl proton obtained in the complexes and the thermodynamic parameters of complexation oftert‐butyl alcohol with acetone‐d6proved to be the same as for thetert‐butyl alcohol–

ISSN:0030-4921    

DOI:10.1002/mrc.1270090809

出版商:John Wiley&Sons Limited    

年代:1977

数据来源: WILEY

摘要:

AbstractInpara‐disubstituted benzenes, the effect of one substituent is transferred to the other composite substituent group and its decreased influence on theorthoandmetaprotons is reflected in their chemical shifts. A graphical presentation of this linear non‐additive dependence can serve as an aid in the correct assignment of the corresponding aromatic region of the spectra. The method is demonstrated on two series of chemical shift data taken from the literat

ISSN:0030-4921    

DOI:10.1002/mrc.1270090810

出版商:John Wiley&Sons Limited    

年代:1977

数据来源: WILEY

摘要:

AbstractThe e.s.r. signal observed during the reaction of aniline and pentyl nitrite in benzene is shown to be due not to phenyldiazoxyl (PhNNO·), as previously reported, but to a mixture of pentyloxyphenylnitroxyl and diphenylnitroxyl radicals, this assignment being made with the aid of deuterium labelling and on the basis of their observed hyperfine coupling constants andg

ISSN:0030-4921    

DOI:10.1002/mrc.1270090811

出版商:John Wiley&Sons Limited    

年代:1977

数据来源: WILEY