ISSN:0030-4921    

DOI:10.1002/mrc.1270060616

出版商:John Wiley&Sons Limited    

年代:1974

数据来源: WILEY

ISSN:0030-4921    

DOI:10.1002/mrc.1270060618

出版商:John Wiley&Sons Limited    

年代:1974

数据来源: WILEY

摘要:

AbstractThe1H NMR spectra of 7,7‐dichloro‐2,5‐dioxabicyclo‐[4.1.0]heptane (1) were analyzed through the application of programs NMRIT and NMREN2.See Ref. 1.The half‐chair conformation of1was obtained from the vicinal coupling constants by the BuysRmethod.S

ISSN:0030-4921    

DOI:10.1002/mrc.1270060602

出版商:John Wiley&Sons Limited    

年代:1974

数据来源: WILEY

摘要:

AbstractDie13C‐chemischen Verschiebungen von methylsubstituierten Harnstoffen, Thioharnstoffen und verwandten Verbindungen werden diskutiert. Es wurde eine Korrelation von13CO und13CS‐chemischen Verschiebungen gefunden. Die mittlere Anregungsenergie im paramagnetischen Verschiebungsanteil wird für die Änderung der Verschiebungen bei Übergang von Carbonyl‐ zu entsprechenden Thiocarbonyl‐Verbindungen als wesentlich angesehen. Einfache HMO‐Berechnungen der Ladungsdichte können die Trends der13C‐chemischen Verschiebunge

ISSN:0030-4921    

DOI:10.1002/mrc.1270060603

出版商:John Wiley&Sons Limited    

年代:1974

数据来源: WILEY

摘要:

AbstractCarbon‐13 NMR chemical shifts of several series of aliphatic hydrocarbon derivatives–‐substituted methanes, ethanes, isopropanes,n‐propanes andn‐butanes–‐were found to have a linear relationship with σ‐electron densities (Qσ) calculated by the method of σ‐included ω‐HMO. A plot of the13C NMR chemical shift of a given carbon in a substituted propane versus that of the corresponding carbon in a substituted butane showed a good linearity with a slope of unity. The values of the13C chemical shifts of then‐butyl derivatives converged rapidly to a constant value as the distance from the substituent increased. Accordingly, the value for the δ‐carbon was found to be constant regardless of the substituent. These results show that the13C NMR chemical shifts of aliphatic hydrocarbon derivatives are mainly dependent on inductive effects. The convergence shown by the experimental results is supported by the calculated results of theQσval

ISSN:0030-4921    

DOI:10.1002/mrc.1270060604

出版商:John Wiley&Sons Limited    

年代:1974

数据来源: WILEY

摘要:

AbstractLa complexation entre le triéthylaluminium et l'éther diéthylique a été étudiée par résonance magnétique du proton. On a pu observer des signaux distincts pour le triéthylaluminium libre et le triéthylaluminium lié. Une stoechiométrie 1:1 est démontrée grâce aux rapports des aires de ces signaux. A plus haute concentration d'éther, des mesures de déplacements chimiques prouvent qu'il n'apparaît pas

ISSN:0030-4921    

DOI:10.1002/mrc.1270060605

出版商:John Wiley&Sons Limited    

年代:1974

数据来源: WILEY

摘要:

AbstractData on13C chemical shifts and13C1H spin coupling constants of norbornane (1), norbornene (2), norbornadiene (3), benzonorbornene (4) and benzonorbornadiene (6) are reported. The non‐equivalence inJ(13CH) values determined from the two bridge methylene proton signals in 2,2,3,3‐tetradeuteriobenzonorbornene (5) and6is briefly discussed. The extraordinary deshielding of the bridge methylene carbon in6has bee

ISSN:0030-4921    

DOI:10.1002/mrc.1270060606

出版商:John Wiley&Sons Limited    

年代:1974

数据来源: WILEY

摘要:

AbstractThe positions of acetyl groups introduced by Friedel‐Crafts reactions into 2,3‐diphenylbenzofuran and its derivatives monomethylated in the 5,6 and 7 positions and dimethylated in the 5,6 positions were determined by means of single and double resonance NMR spectra. It was found that the first acetyl group occupies position 6 for all 6‐unmethylated compounds and position 5 for 6‐methylated compounds. The next two acetyl groups enter theparapositions (4′ and 4″) of the phenyl groups with the same probability. When positions 5 and 6 are methylated the acetyl group enters positions 7,4′ and 4″ which are found to be of almost equal reactivity. The NMR parameters of compounds stu

ISSN:0030-4921    

DOI:10.1002/mrc.1270060607

出版商:John Wiley&Sons Limited    

年代:1974

数据来源: WILEY

摘要:

AbstractThe NMR spectra of 1,1‐dichloro‐2,2‐difluoroethane (1), 1,1‐dibromo‐2,2‐difluoroethane (2),mesoanddl1,2‐dichloro‐1,2‐difluoroethane (3) and 1,1,2,2‐tetrachloroethane (4) have been analysed in a number of solvents. The19F spectrum of3in L‐bornyl acetate at 56·4 and 94·1 MHz allows an unambiguous identification of themesoanddlisomers. The spectra of thedandlisomers consist of two AA′XX′ spectra with a small chemical shift difference between thedandlforms, whilst that of themesoform is an apparent AA′XX′ spectrum at 56·4 MHz but an ABXX′ spectrum at 94·1 MHz, the19F nuclei in this isomer being anisochronous in this solvent. The observed solvent and temperature dependence of the couplings of1, 2,meso3and4when combined with the calculated solvation energies, allow the determination of the rotamer energies and couplings in these molecules. The rotamer energy differences (Eg–Et) in the liquid and vapour states are 0·6 and −0·2 kcal/mol (1); 0·4 and −0·5 kcal/mol (2); 0·9 and 0·2 kcal/molmeso(3) and −0·1 and −0·8 kcal/mol (4). The3J(HH),3J(HF) and3J(FF) couplings for the distinct rotamers are considered together with those of similarly constituted molecules. The general agreement demonstrates that the solvation theory may be applied to multisubstituted ethanes without any basic modifications. Thetransoriented HH couplings show a linear substituent electronegativity dependence, which differs appreciably from that obtained for disubstituted ethanes, however. Thegauchecouplings show the influence of dihedral angle variations as well as substituent electronegativity. The rotamer3J(FF)

ISSN:0030-4921    

DOI:10.1002/mrc.1270060608

出版商:John Wiley&Sons Limited    

年代:1974

数据来源: WILEY

摘要:

AbstractLe spectre de Résonance Magnétique Nucléaire de huit spirophosphoranes à liaison PH a été enregistré en présence de chélate d'europium. L'addition du complexe d'europium amène la levée partielle ou totale de dégénérescence des spectres. Les modifications observées dans les déplacements chimiques permettent de proposer une attribution de positionendoouexode certains signaux. L'addition du complexe d'europium entraîne, dans certains cas, une modification de l'équilibre entre les formes phosphites e

ISSN:0030-4921    

DOI:10.1002/mrc.1270060609

出版商:John Wiley&Sons Limited    

年代:1974

数据来源: WILEY