ISSN:0030-4921    

DOI:10.1002/mrc.1270080516

出版商:John Wiley&Sons Limited    

年代:1976

数据来源: WILEY

摘要:

Abstract13C n.m.r. spectra have been measured for thirty‐two polychloroalkenes including (i) monosubstituted compounds CH2CHCClnH2−nX, where X stands for H, Cl, alkyl, and trisubstituted alkenes CCl2CHAlk, none of which form geometric isomers; (ii) disubstituted compounds RCHCHR′; (iii) and (iv) trisubstituted compounds of the types RCClCHR′ and CHClCClR, respectively. Compounds (ii) to (iv) represent either individual isomers or mixtures of theZandEforms. In the case of compounds (ii) and (iii), the ordering of chemical shifts is δE>δZfor thesp2‐carbon atoms and δE<δzfor the adjacent tetrahedral ones. On the contrary, the signals of thesp2‐carbon atoms of compounds (iv) obey the rule δE<δz. The effect of vinyl and allyl groups as substituents on the13C chemical shifts of chlorine‐containing groups is discussed. The dependence of thesp2‐carbon spin–spin coupling constantsJ(13C1H) on the number of chlorinated substi

ISSN:0030-4921    

DOI:10.1002/mrc.1270080502

出版商:John Wiley&Sons Limited    

年代:1976

数据来源: WILEY

摘要:

AbstractFrom ΔGTc≠values obtained by1H and13C dynamic nuclear magnetic resonance studies of the same dynamic process, it is possible to estimate ΔH≠and ΔS≠. Nevertheless, the accuracy of the temperature measurement is a factor which limits the applicability of this method. A very simple procedure for calibrating the usual temperature sensors is described, which can be applied to all types of n.m.r. probes. By the use of this procedure it is possible to measure coalescence temperatures in1H and13C n.m.r. with such an accuracy that ΔS≠can be effectively determined from the difference between

ISSN:0030-4921    

DOI:10.1002/mrc.1270080503

出版商:John Wiley&Sons Limited    

年代:1976

数据来源: WILEY

摘要:

AbstractThe anion radical of acetylacetonate is formed by the reaction of nickel (II) acetylacetonate with Grignard reagents. From the two coupling constants found in the e.s.r. spectrum, the one of 2·6 G was assigned to the methine proton and the one of 12·5 G to the six equivalent methyl protons of acetylacetonate. The calculations of spin densities for the anion radical of acetylacetonate by the INDO method are in relatively good agreement with experimen

ISSN:0030-4921    

DOI:10.1002/mrc.1270080504

出版商:John Wiley&Sons Limited    

年代:1976

数据来源: WILEY

摘要:

AbstractThe signs and magnitudes of every fluorine–fluorine coupling constant in perfluoroquinoline (1), 2,4‐dichloropentafluoroquinoline (2) and 2‐bromohexafluoroquinoline (3) have been determined by19F n.m.r. These provide an unambiguous assignment of the spectrum of the first compound and its derivatives. Inter‐ring fluorine–fluorine coupling constants were found to be positive over an odd number of bonds and negative over an even number of bonds, similar to that observed in proton–proton coupling constants in multicyclic systems.The19F chemical shifts of perfluoroquinoline and its protonated salt are reported and directly correlated with SCF MO calculated π‐electron densities at both fluorine and bonde

ISSN:0030-4921    

DOI:10.1002/mrc.1270080505

出版商:John Wiley&Sons Limited    

年代:1976

数据来源: WILEY

摘要:

AbstractDie1H‐NMR‐Spektren einer Reihe aliphatisch und phenylsubstituierter Alkendiine werden vorgestellt und, unter Berücksichtigung einiger literaturbekannter Verbindungen, chemische Verschiebungen und Kopplungskonstanten diskutiert.Die chemischen Verschiebungen der Protonen der untersuchten isomeren Alkendiine RCCCCCHCH2, RCHCHCCCCH und RCHCHCCCCCH3(R = H, Alkyl, C6H5, C6H4OCH3‐p,) lassen sich hinsichtlichcis/trans‐Isomerie und Substitution an der Doppelbindung befriedigend mit elektronischen Effekten und molekularen Magnetfeldern der Mehrfachbindungen erklären. Die Kopplungs‐konstanten erweisen sich als kaum abhängig von der Substitution an der Doppelbindung. Über die Diacetylengruppierung hinweg können Kopp

ISSN:0030-4921    

DOI:10.1002/mrc.1270080506

出版商:John Wiley&Sons Limited    

年代:1976

数据来源: WILEY

摘要:

AbstractAll carbon resonances in the title compounds have been unequivocably assigned. Steric effects in theperisubstituted compounds have been compared with analogous effects in naphthalene and benzo[b]furan. The observed effects are not explained by current theory. Unusual deshielding steric shifts are observed at some carbons. Methyl substituent effects are not additive at any position in the sterically crowded 2,3‐disubstituted compound

ISSN:0030-4921    

DOI:10.1002/mrc.1270080507

出版商:John Wiley&Sons Limited    

年代:1976

数据来源: WILEY

摘要:

Abstractcis(4‐H,11b‐H)‐4‐Aryl‐1,6,7,11b‐tetrahydro‐2H,4H‐[1,3]oxazino [4,3‐a]isoquinoline and the related thiazino compound preferentially adopt in solution the O (or S) insidecis‐conformation in contrast tocis(1‐H,4a‐H)‐1‐arylperhydropyrido[1,2‐c][1,3]oxazine which adopts thetransfused conformation. 1‐(β‐Hydroxy‐ethyl)‐1,2,3,4‐tetrahydro‐β‐carboline condenses with benzaldehyde to give the 1,3‐oxazine derivative rather than t

ISSN:0030-4921    

DOI:10.1002/mrc.1270080508

出版商:John Wiley&Sons Limited    

年代:1976

数据来源: WILEY

摘要:

AbstractDie Bestimmung der Stereochemie einer Reiheexo/endo‐isomerer 9.10‐Dihydro‐ bzw. Tetrahydrodicyclopentadien‐9.10‐diole (exo/exobzw.endo/endo) unter Verwendung von Eu(fod)3zur Auftrennung ihrer1H‐NMR‐Spektren wird beschrieben. Die für halbmolares Verhältnis Eu(fod)3/Diol bestimmten Verschiebungswerte ΔEu gestatten dabei eine eindeutige stereochemische Zuordnung der Verbindungen. Die ΔEu‐Werte werden mit dem Abstand Hi…O

ISSN:0030-4921    

DOI:10.1002/mrc.1270080509

出版商:John Wiley&Sons Limited    

年代:1976

数据来源: WILEY

摘要:

AbstractLa comparaison après simulation des spectres RMN à haut champ des tétrabromo‐2,2,6,6 méthyl‐4 ettertiobutyl‐4 cyclohexanones (1et2) nous a permis de mettre en évidence par l'étude des constantes de couplage, en particulierJgem,Jea,Jaaet4Jet des déplacements chimiques que1présente à l'état dissous une isomérie de rotation.Ce travail confirme les conclusions auxquelles nous avait conduits une étude par spectroscopie d'absorption dans l'infrarouge de1dans la région des vibrations de

ISSN:0030-4921    

DOI:10.1002/mrc.1270080510

出版商:John Wiley&Sons Limited    

年代:1976

数据来源: WILEY