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  • Articles  (300)
  • Analytical Chemistry and Spectroscopy  (300)
  • 1970-1974  (300)
  • 1971  (300)
  • 1
    Electronic Resource
    Electronic Resource
    Temperature dependence of the NQR frequencies and relaxation times in Menshutkin's complexes on the basis of arsenic trichloride and tribromide (1971)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 3 (1971), S. 515-526 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The temperature dependence of NQR frequencies and spin-lattice relaxation times in Menshutkin's complexes, prepared on the basis of AsCl3 and AsBr3 have been investigated.The rotational oscillation frequencies νt and the average life times τa of rotational oscillation quanta have been calculated by both the Bayer and Woessner-Gutowsky theories.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270030504
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  • 2
    Electronic Resource
    Electronic Resource
    Proton magnetic resonance spectra of thenyl derivatives - IIFor Part I, see Ref. 1.. Chloromethylthiophenes and some dithienylmethanes (1971)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 3 (1971), S. 527-531 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: PMR spectra of thirty-eight chloromethylthiophene and seven dithienylmethane derivatives were observed at 60 or 40 MHz. The chemical shifts of methylene protons were 4·63 to 5·25 ppm for monosubstituted 2-chloromethylthiophenes and 4·37 to 4·56 ppm for monosubstituted 3-chloromethylthiophenes, respectively, with reference to TMS. Those for 2,2′ -dithienylmethanes, which have one substituent in each ring, were 4·12 to 4·34 ppm. These shifs are useful for determination of the positions of the methylene groups in the related compounds. The long-range coupling constants observed for methylene proton signals are also useful for the determination of the positions of substituents.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270030505
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  • 3
    Electronic Resource
    Electronic Resource
    Etude RMN de l'Acetone en Solution dans une Phase Nematique (1971)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 3 (1971), S. 533-537 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The NMR spectrum of acetone oriented in the nematic phase of butyl-p-(p′-ethoxyphenyloxycarbonyl) phenyl carbonate has been studied in the 48° to 58°C temperature range. The determination of direct coupling constants allows the computation of orientation parameters; these values lead us to emphasize the intervention of polarizability in orientation phenomena.
    Notes: Le spectre RMN de l'acétone orientée dans le p-(p′ ethoxyphenyloxycarbonyl)phényl carbonate de butyle est étudié dans l' intervalle de température 48° à 58°C. La mesure des constantes de couplage direct permet de calculer les facteurs d' orientation moléculaires; ceux-ci permettent de mettre en évidence ici l' intervention de la polarisabilité dans le phénoméne d' orientation.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270030506
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  • 4
    Electronic Resource
    Electronic Resource
    Nuclear magnetic resonance spectra of carbanions - VIFor Part V, see Ref. 1.. Cumyl-, α-methylbenzyl- and benzyl carbanionsFor a preliminary paper of a part of this work, see Ref. 2. (1971)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 3 (1971), S. 539-543 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The proton magnetic resonance spectra of the three title carbanions have been observed in THF with potassium as a counter ion. The ortho-protons in the α-methylbenzyl carbanion are nonequivalent at room temperature. This shows that the α-carbon in this carbanion is in the near-sp2 configuration. The aromatic proton chemical shifts of the benzylpotassium obtained here are at higher shielding than those of benzyllithium reported previously by Sandel and Freedman. This seems to arise from the different ionic nature of the bonds between carbon and metal in the carbanions.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270030507
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  • 5
    Electronic Resource
    Electronic Resource
    NMR-Untersuchungen bei Prolin-enthaltenden DiketopiperazinenDiese Arbeit wurde im Organisch-Chemischen Institut der TU-München druchgeführt. Für diese Möglichkeit bin ich der Alexander von Humboldt-Stiftung zu Dank verpflichtet. (1971)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 3 (1971), S. 545-550 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The NMR-spectra of cis- and trans-isomers of proline-containing diketopiperazines were investigated. It was demonstrated that the differences in the spectra are connected to the different position (pseudoaxial or pseudoequatorial) of the substituent (α-hydrogen atom, α-methyl-group, α-isopropyl-group).
    Notes: Bei NMR-Untersuchungen der cis- und trans-Reihe Prolin-enthaltender Diketopiperazine konnten Unterschiede zwischen den Signalen pseudoaxialer und pseudoäquatorialer Substituenten (α-Proton, α-Methylgruppe, α-iso-Propylgruppe) festgestellt werden.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270030508
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  • 6
    Electronic Resource
    Electronic Resource
    Nuclear magnetic resonance studies of internal rotation - IIIFor Part II, see Ref. 1. Rotational barriers in META- and PARA-substituted N, N-dimethylcinnamamides (1971)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 3 (1971), S. 551-556 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rotational barriers about the C—N bond of eight m- and p-substituted N, N-dimethyl cinnamamides have been determined by the iterative total line shape NMR method. The ΔG298·2-≠ values have been correlated with the substituent constants σ, σn and σ+. By comparison of the results with literature data, some conclusions about the accuracy of the barrier determination as well as the transmittance of polar effects in conjugated amides have been drawn.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270030509
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  • 7
    Electronic Resource
    Electronic Resource
    A semi-empirical MO calculation of 13C chemical shifts - I: Alkanes (1971)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 3 (1971), S. 567-573 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 13C shielding constants have been calculated for a series of alkanes, methane to pentane. The quantities σd and σp have been obtained, using an average excitation energy approximation and the extended Hückel MO wave functions in terms of the Pople method. The results fit the experimental data and the VB results of Grant et al. fairly well. The quantity σd varies within a wide range for carbon atoms of various degrees of substitution. Two conformations of the hydrocarbons studied have been calculated. The results show that the 13C chemical shifts may be used for conformational analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270030511
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  • 8
    Electronic Resource
    Electronic Resource
    Tris(dipivaloylmethanato)europium induced shifts of proton resonances in π-deficient nitrogen heterocycles (1971)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 3 (1971), S. 575-582 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tris(dipivaloylmethanato)europium [Eu(DPM)3]induced shifts of the proton resonances of pyridine and its 2-methyl, 3-methyl, 2,3-dimethyl and 2,5-dimethyl derivatives, pyridazine, pyrimidine, pyrazine, quinoline, isoquinoline, 1,6-, 1,7- and 1,8-naphthyridine, cinnoline, phthalazine, quinazoline, quinoxaline, 1,4,5- and 1,4,6-triazanaphthalene, pteridine, acridine, phenanthridine and 1, 10-phenanthroline, have been measured for solutions containing 0·1, 0·3 and 0·5 molar equivalents of Eu(DPM)3. Differences in the behaviour of these heterocycles are discussed in terms of the steric relationship between the heterocycle and the complex. The 3 cos2 φ term, present in the expression for calculating pseudo-contact shifts, is shown to be important. The order of basicity of these heterocycles, as measured by their pKa values, cannot be used to predict the order of Eu(DPM)3 induced chemical shifts.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270030512
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  • 9
    Electronic Resource
    Electronic Resource
    Nuclear magnetic resonance studies of methyl-5, 6-dicarboxy-2-norbornene derivatives (1971)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 3 (1971), S. 557-565 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A simple procedure is provided for the quantitative analysis of Diels-Alder adduct prepared from commercial methylcyclopentadiene and maleic anhydride by NMR spectra without further separation of its components. The adduct is considered as a mixture of endo norbornene derivatives (Cn), (Dn), (E) and (Fn) which are obtained from 1-, 2- and 5-methylcyclopentadiene and cyclopentadiene, respectively.The quantitative analysis of the adduct can be made on a basis of the ratio of the signal intensities of the olefinic protons in the adduct. The result shows that the adduct prepared under mild conditions mainly consists of three norbornene derivatives (Cn), (Dn) and (Fn), with a negligibly small amount of (E). When the adduct prepared under mild conditions is heated, it contains the exo isomers (Cx), (Dx) and (Fx). The ratio of the endo and the exo norbornene derivatives, i.e. ((Cn) + (Dn) + (Fn)):((Cx) + (Dx) + (Fx)), may be estimated from the signal intensities of the 5- and 6-protons.As the result of the analyses of the adducts which are obtained by heating at different temperatures the adduct prepared under mild conditions, the mole fraction of 2-methyl isomers (Dn) and (Dx), which is found to be 58 % in the adduct prepared at - 15°C, keeps on increasing with rising temperature and shows almost the same value, ∼86%, when heated above 150°C. Therefore, the equilibrium between 1-methyl and 2-methyl isomers does not change above 150°C. On the other hand, the isomerization from endo to exo isomers is not found below 110°C, and then exo isomers keep on increasing above 140°C.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270030510
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  • 10
    Electronic Resource
    Electronic Resource
    Proton magnetic resonance spectrum of thiophen dissolved in a nematic solvent (1971)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 3 (1971), S. 583-587 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The PMR spectrum of thiophen dissolved in a nematic phase is reported. This spectrum has been analysed iteratively. The ratios of the various inter-proton distances determined in this study are in good agreement with those previously reported.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270030513
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