摘要:

AbstractIn order to determine the effect of a single methyl group on the chemical shifts of protons in a cyclohexane ring, methylcyclohexane‐1,2,3,3,5,5,‐d6has been synthesized. The protons in the 4‐position and the 2,6‐equatorial protons are not significantly different from those in ring‐frozen cyclohexane. The 2,6‐axial protons, however, experience an up‐field shift of about 15 Hz from the position of the other axial protons. These observations are discussed in terms of the structure of meth

ISSN:0030-4921    

DOI:10.1002/mrc.1270010502

出版商:John Wiley&Sons Limited    

年代:1969

数据来源: WILEY

摘要:

AbstractDas Protonenresonanz‐Spektrum des Acetyl‐cyclobutadien‐eisentricarbonyls wurde einschließlich aller beobachtbaren13CH‐Kopplungskonstanten vermessen. Die Kopplungen warden zugeordnet und im Hinblick auf Molekülstruktur und Bindungsverhältnisse diskutiert. Auf Grund der Messungen kann die Struktur eines cyclisch‐konjugierten Diens mit alternierenden Doppel‐ und Eingachbindungen ausge

ISSN:0030-4921    

DOI:10.1002/mrc.1270010503

出版商:John Wiley&Sons Limited    

年代:1969

数据来源: WILEY

摘要:

AbstractThe NMR spectral parameters for some bromo‐ and iodo‐substituted fluorobenzenes are presented, and the derivedmeta‐and para‐ fluorine‐fluorine couplings are shown to be in accord with the predictions made by Abrahamet al., using an additive substituent constant scheme. While the approximation of additive substituent effects is quite good, it is shown, however, that with highly accurate experimental values there are small deviations from perfect additivity. The existence of a large solvent effect on3JFFis demonstrated and the mechanism of this effect is discussed. It is emphasized that certain discrepancies in the literature between various values of the same3JFFmay be due to this large, hitherto unrecognized solvent d

ISSN:0030-4921    

DOI:10.1002/mrc.1270010504

出版商:John Wiley&Sons Limited    

年代:1969

数据来源: WILEY

摘要:

AbstractFluorine nuclear magnetic resonance (F‐NMR) has been used to determine dissociation constants for multipolar complexes formed by severalp‐substituted fluorobenzenes in CCl4and cyclohexane at 25°. Data in CCl4were also obtained at −20°. The results are interpreted in simplified terms as dipole‐dipole interactions which lead to a complex of net zero dipole moment. Although the dissociation constants are not of high accuracy, the values obtained do indicate that both polarity and steric effects are important in the presumed multipolar

ISSN:0030-4921    

DOI:10.1002/mrc.1270010505

出版商:John Wiley&Sons Limited    

年代:1969

数据来源: WILEY

摘要:

AbstractPMR spectra of substituted 4‐piperidones in base and salt forms in D2O, water and other solvents are reported, and spectral characteristics interpreted in terms of equilibria between free ketone and 4,4‐dideuteroxy (or hydroxy) forms. It is shown that 1‐mono and 1,3‐disubstituted‐4‐piperidones exist extensively as the corresponding dideuteroxy (or hydrated) species in D2O (or H2O) provided the ring nitrogen atom is positively charged, and that 3‐substituents decrease the population of these forms. The facile D/H exchange of α‐protons in the piperidone bases is a

ISSN:0030-4921    

DOI:10.1002/mrc.1270010506

出版商:John Wiley&Sons Limited    

年代:1969

数据来源: WILEY

摘要:

AbstractNMR solvent effects induced by aromatic solvents on some 1,4‐dioxanes, 1,3‐dioxolanes and on some sulphur analogue derivatives are reported. The shielding effect of the aromatic solvents is examined in respect to the structure of the sol

ISSN:0030-4921    

DOI:10.1002/mrc.1270010507

出版商:John Wiley&Sons Limited    

年代:1969

数据来源: WILEY

摘要:

AbstractA detailed study has been made on the1H nuclear magnetic resonance (NMR) spectra of 5,6‐dicarboxy‐2‐norbornene derivatives, whose chemical shifts and geminal, vicinal and long‐range spin‐spin coupling constants were determined. Each signal of the spectra of these derivatives shows a slight low‐field shifts compared with norbornene itself. In the case of five methyl esters studied in this work, the signal of the 7s‐proton remains at approximately the same position in all the compounds, but that of the 7a‐proton is more variable. For the chemical shifts of the 7a‐proton of the five methyl esters, an additive rule seems to hold: that the magnitude of the low‐field shift, from the 7a‐signal of norbornene itself, is obtained by adding each of the effects of the carboxyl and the carbomethoxy groups substituted at theendo‐5‐(or 6‐) or theexo‐5‐(or 6‐) positions of the norbornene ring. In most of the derivatives considered in this work, the spin‐spin coupling constants, except those between bridgehead and bridged methylene protons, are about 1 to 2 Hz smaller than those of many other norbornene derivatives already studied. This fact seems to suggest that norbornenes, which have two bulky adjacent substituents at 5‐ and 6‐positions, may su

ISSN:0030-4921    

DOI:10.1002/mrc.1270010508

出版商:John Wiley&Sons Limited    

年代:1969

数据来源: WILEY

ISSN:0030-4921    

DOI:10.1002/mrc.1270010509

出版商:John Wiley&Sons Limited    

年代:1969

数据来源: WILEY

ISSN:0030-4921    

DOI:10.1002/mrc.1270010510

出版商:John Wiley&Sons Limited    

年代:1969

数据来源: WILEY

ISSN:0030-4921    

DOI:10.1002/mrc.1270010511

出版商:John Wiley&Sons Limited    

年代:1969

数据来源: WILEY