ISSN:0030-4921    

DOI:10.1002/mrc.1270020402

出版商:John Wiley&Sons Limited    

年代:1970

数据来源: WILEY

摘要:

AbstractDie chemischen Verschiebungen der13C‐Resonanzen für freies und protoniertes 1.10‐Phenanthrolin werden bestimmt und mit Hilfe der in Teil I1und Teil III2beschriebenen π‐ und (σ + π)‐MO‐Elektronenrechnungen interpretiert.Bei der Protonierung ist die Verschiebung der13C‐Signale der dem Stickstoff benachbarten C‐Atome zu höherem Feld charakteristisch; dieser Effekt wird mit einer Verringerung der N–C‐Überlappungsbesetzung gedeutet. Für das mono‐ und diprotonierte 1.10‐Phenanthrolin wird eine relativ geringe formale Ladung am Stickstoff festege

ISSN:0030-4921    

DOI:10.1002/mrc.1270020403

出版商:John Wiley&Sons Limited    

年代:1970

数据来源: WILEY

摘要:

AbstractMeasurements are reported on the nuclear magnetic resonance spectra of the acetyl protons of a series of substituted acetophenones. Although the extreme values of the chemical shifts, δ COCH 3for themeta‐ andpara‐ substituted compounds differ only by 0·2 units, the values themselves are linearly related to the Hammett substituent constants. No such relationship exists for theortho‐substituted compounds. The magnitude of the chemical shift is independent of substrate concentration over a five‐f

ISSN:0030-4921    

DOI:10.1002/mrc.1270020404

出版商:John Wiley&Sons Limited    

年代:1970

数据来源: WILEY

摘要:

Abstract—Intramolecular OH… N hydrogen bonding between the hydroxylic and terminal amino groups of α‐hydroxy‐N‐caproylhydrazobenzene (5) permitsJ(HCOH) to be observed in most solvents. The configuration and conformation of5are discussed and an HCOH dihedral angle (ϕ) of 145° is calculated. Solvent effects onJ(HCOH) as well as the role they appear to exert in restricting internal rotation of the phenyl substitue

ISSN:0030-4921    

DOI:10.1002/mrc.1270020405

出版商:John Wiley&Sons Limited    

年代:1970

数据来源: WILEY

摘要:

AbstractThe proton NMR spectra of fourcis/transpairs of 1,2‐disubstituted olefins have been analysed. The observed trends of the olefinic, vicinal and allylic proton‐proton coupling constants are discussed in terms of rehybridization at thesp2carbon atoms. It is found that in these substances thetrans‐allylic couplings are generally more negative than thecis‐allylic couplings contrary to Barfield's1theoretical prediction but in agreement with some earlier experimental data. Steric hindrance betweencisoidsubstituents is cited as the probable origin of this end related

ISSN:0030-4921    

DOI:10.1002/mrc.1270020406

出版商:John Wiley&Sons Limited    

年代:1970

数据来源: WILEY

摘要:

AbstractThe proton chemical shifts are reported for monosubstituted naphthalenes, quinolines and quinoxalines. Together with literature data, these chemical shifts are compared with the parent compounds and substituent effects evaluated statistically. The effect of substituents parallels that in benzenes, but is modified by bond fixation, steric hindrance and other effects which can, at least qualitatively be understood. The treatment enables estimation of likely chemical shifts for ABC spectra in fused aromatic systems which should facilitate the solution of such spectra.

ISSN:0030-4921    

DOI:10.1002/mrc.1270020407

出版商:John Wiley&Sons Limited    

年代:1970

数据来源: WILEY

摘要:

AbstractLes spectres de Dérivés alléniques du plomb, de l'étain et du mercure permettent d'observer les satellites dûs aux couplages métal‐proton à travers deux et quatre liaisons. L'analyse de ces satellites montre que2J(XH) et4J(XH) sont de signes contraires pour X =207Pb,119Sn,117Sn et de même signe pour X =199Hg.Les signes absolus probables des constantes de couplage réduites sont discutés en fonction des résultats de la littérature:2K(XCH) est très probablement positif pour X =207Pb,119Sn,117Sn et199Hg.4K(XCCCH) est probablement négatif pour X =207Pb,119Sn,

ISSN:0030-4921    

DOI:10.1002/mrc.1270020408

出版商:John Wiley&Sons Limited    

年代:1970

数据来源: WILEY

摘要:

AbstractNMR spectra of several styrene, stilbene and stilbazole oxides have been determined, and chemical shifts and coupling constants have been correlated withcis‐andtrans‐configurations. Assignments have been made for all protons, and double resonance technique and13CH coupling constants have been used in some particular cases. An explanation is proposed for the observation that chemical shifts of oxirane protons are higher forcisthan fortransis

ISSN:0030-4921    

DOI:10.1002/mrc.1270020409

出版商:John Wiley&Sons Limited    

年代:1970

数据来源: WILEY

摘要:

AbstractTrans‐4‐t‐Bu‐6‐R‐1,3‐dioxanes (R = Me, Priandcyclohexyl) show temperature‐dependent values for2J(H—2) and3J(H—4(6), H—5) in their PMR spectra. This is the result of the presence of twist‐boat conformations. With the aid of typical limit‐values of2J(H—2) for the chair and twist forms, the amount of flexible conformations were determined as a function of temperature (Table 2), allowing the determination of the enthalpy change for chair‐twist interconversion in 1,3‐dioxane itself (6·2 ± 0·3 kcal/mole). Typical values for2J(H—2) were obtained from a study of low temperature spectra and from appropriate model compounds of which 4‐(1′‐adamantyl)‐6‐t‐Bu‐1,3‐dioxane served as the model for a ge

ISSN:0030-4921    

DOI:10.1002/mrc.1270020410

出版商:John Wiley&Sons Limited    

年代:1970

数据来源: WILEY

摘要:

AbstractQuantitative analysis of isomers by NMR has been carried out in the measurement of species whose components present simple and sufficiently isolated spectra. Generally, the substituted aromatic proton splits into complicated spectral lines due to spin‐spin coupling. The ring proton spectra of dichlorophenol isomers show a pattern peculiar to the three spin system. It was found that some of the signal attributable to these compounds appear in a position slightly isolated from each other. Therefore, we established the quantitative analysis method for dichlorophenol, using the signal intensity method. From the result of the quantitative analysis, the lowest detectable concentration was 1·1% (±0·3% at the standard deviation). The accuracy of the peak intensity method was found to be ±1·8% within the 50 to 80 mol% concentration range of 2,4‐dichloropheno

ISSN:0030-4921    

DOI:10.1002/mrc.1270020411

出版商:John Wiley&Sons Limited    

年代:1970

数据来源: WILEY