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'Solvent Effect' in keywords Facet   section ZfN Section B  [X]
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1998 (1)
1981 (3)
1978 (1)
1Author    FayezY. Khalil, M. T. HannaRequires cookie*
 Title    Kinetic Study of the Acid Hydrolysis of Ethyl Hydrogen Succinate in Binary Solvent Mixtures  
 Abstract    The specific rate constants for the acid-catalysed hydrolysis of ethyl hydrogen succinate in water and in a series of acetone-water and dioxane-water mixtures were determined at 30-45 °C. The solvent composition covered the range 0-90% by weight of the organic solvent. The rate was found to decrease to a minimum at about 80% of the organic solvent then to increase again with successive addition of the latter. In dioxane-water medium a slight initial increase in rate on the first addition of dioxane to water was observed and attributed to an increase in the number of "free" water molecules. The activation energy showed only slight dependence on solvent composition. The radius of the activated complex was calculated in the two media. The thermodynamic parameters were evaluated and discussed in terms of solvent composition. The reaction proved to be essentially an ion-dipole rather than an ion-ion interaction. A comparative discussion of the specific solvent effects of the two solvent systems under consideration is presented, based on the respective bond energies as given by the heats of mixing of the solvent components. 
  Reference    Z. Naturforsch. 33b, 1479—1483 (1978); received April 25 1978 
  Published    1978 
  Keywords    Ethyl Hydrogen Succinate, Acid Hydrolysis, Kinetics, Solvent Effects, Thermodynamic Parameters 
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 TEI-XML for    default:Reihe_B/33/ZNB-1978-33b-1479.pdf 
 Identifier    ZNB-1978-33b-1479 
 Volume    33 
2Author    CliffordW. Fonga, HamishG. GrantRequires cookie*
 Title    Solvent Effects on the Carbon - 13 NMR Chemical Shifts and Rotational Barriers of N,N-Dimethylbenzamide - Solvent Enhanced n Polarization  
 Abstract    The 13 C NMR chemical shifts of N,N-dimethylbenzamide in thirty solvents have been measured at high dilution. The solvent induced chemical shifts (s.i.c.s.) of the carbonyl group carbon atom in twenty three solvents and the thermodynamic barriers to rotation about the C-N bond in eleven solvents are linearly related to the solvent parameter, ET(30). Multi-parametric analysis of the carbonyl s.i.c.s. indicates hydrogen bond donor effects are more important than polar effects. Rotational barriers for N,N-dimethylbenz-amide may be determined by measurement of the 13 C chemical shift of the carbonyl group in a particular solvent. The s.i.c.s. of the aromatic ring carbon atoms may be explained by the polarization of the aromatic ji electron system induced by the solvent enhanced polarization of the dimethylcarboxamido moiety. Hydrogen bonding solvents and polar solvents result in two effective dipoles on the dimethylcarboxamido moiety, which polarize the aromatic n electron system differently. 
  Reference    Z. Naturforsch. 36b, 585—595 (1981); received May 19 1980/January 21 1981 
  Published    1981 
  Keywords    Solvent Effects, 13 C NMR Spectra Rotational Barriers, N, N-Dimethylbenzamide 
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 TEI-XML for    default:Reihe_B/36/ZNB-1981-36b-0585.pdf 
 Identifier    ZNB-1981-36b-0585 
 Volume    36 
3Author    J. Manzur, G. GonzálezRequires cookie*
 Title    Solvent Effects on the IR Spectra of N-Methylacetamide  
 Abstract    The solvent effect on the v(N-H) amide I and amide II IR bands of N-methylacetamide were investigated. The frequency shifts could be related to the solvent donor and acceptor num-bers by mean of a two parameters relationship that accounts for the mutual influence between the two interacting sites of the amide. 
  Reference    Z. Naturforsch. 36b, 763—764 (1981); received January 2 1981 
  Published    1981 
  Keywords    Solvent Effect, Amidic Bond, N-Methylacetamide, Hydrogen Bonding Interactions 
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 TEI-XML for    default:Reihe_B/36/ZNB-1981-36b-0763_n.pdf 
 Identifier    ZNB-1981-36b-0763_n 
 Volume    36 
4Author    Waldemar Adam, Omar CuetoRequires cookie*
 Title    3,3-Dimethyl-4 [2-methyl-l-propenyl] -1,2-dioxetane: Its Thermal Stability and Chemiluminescent Properties  
 Abstract    The alkenyl-substituted 1,2-dioxetane (1) was prepared by photosensitized singlet oxygenation of 2,5-dimethyl-2,4-hexadiene and its activation and excitation parameters determined. It is shown that dioxetane (1) is comparable in its thermal stability to alkyl-substituted dioxetanes and an inefficient chemical source of electronic excitation. 
  Reference    Z. Naturforsch. 36b, 1653—1654 (1981); received June 29 1981 
  Published    1981 
  Keywords    1, 2-Dioxetanes, Chemüuminescence, Activation Parameters, Excitation Yields, Solvent Effects 
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 TEI-XML for    default:Reihe_B/36/ZNB-1981-36b-1653.pdf 
 Identifier    ZNB-1981-36b-1653 
 Volume    36 
5Author    Ulrich Nagel, Christoph RollerRequires cookie*
 Title    Enantioselective Catalysis, XVII [1], Enantioselective Catalytic Hydrogenation of Unfunctionalized Ketones  
 Abstract    Three diastereomeric rhodium bisphosphane complexes have been applied to asymmetric hydrogenation of unfunctionalized, non-chelating aliphatic and aromatic ketones. The ee values o f the catalysis products differ considerably for the diastereomerical catalysts. 70% ee were obtained in hydrogenating butyrophenone, and 83.7% ee for pinacoline. The results depend strongly on the solvent used. 
  Reference    Z. Naturforsch. 53b, 267—270 (1998); received January 15 1998 
  Published    1998 
  Keywords    Enantioselective Hydrogenation, Unfunctionalized Ketones, Rhodium, Salt Effect, Solvent Effect 
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 TEI-XML for    default:Reihe_B/53/ZNB-1998-53b-0267.pdf 
 Identifier    ZNB-1998-53b-0267 
 Volume    53