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  • kinetics  (3)
  • Gibbs energies of transfer  (2)
  • Solvolysis  (2)
  • Springer  (5)
  • 1
    Electronic Resource
    Electronic Resource
    The kinetics of the solvolysis of chloropentacyanocobaltate(III) ions in water containing 2-methoxyethanol or diethylene glycol: A contrast with the effect of more hydrophobic cosolvents (1994)
    Springer
    Journal of solution chemistry 23 (1994), S. 1089-1100 
    Details
    ISSN: 1572-8927
    Keywords: Solvolysis ; kinetics ; aqueous solvent mixtures ; Co(III) complexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetics of the solvolysis of [Co(CN)5Cl]3− have been investigated in water +2-methoxyethanol and water + diethylene glycol mixtures. Although the addition of these linear hydrophilic cosolvent molecules to water produces curvature in the variation of log(rate constant) with the reciprocal of the dielectric constant, their effect on the enthalpy and entropy of activation is minimal, unlike the effect of hydrophobic cosolvents. The application of a Gibbs energy cycle to the solvolysis in water and in the mixtures using either solvent-sorting or TATB values for the Gibbs energy of transfer of the chloride ion between water and the mixture shows that the relative stability of the emergent solvated Co(III) ion in the transition state compared to that of Co(CN)5Cl3− in the initial state increases with increasing content of cosolvent in the mixture. By comparing the effects of other cosolvents on the solvolysis, this differential increase in the relative stabilities of the two species increases with the degree of hydrophobicity of the cosolvent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00976258
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  • 2
    Electronic Resource
    Electronic Resource
    Ions in Aqueous Acetic Acid Mixtures: Solvent Reorganization around Protons and Gibbs Energies of Transfer from Water (2000)
    Springer
    Journal of solution chemistry 29 (2000), S. 271-287 
    Details
    ISSN: 1572-8927
    Keywords: Ions ; solvent mixtures ; Gibbs energies of transfer ; acetic acid-water mixtures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The photo-absorbing, basic sensor, 4-nitroaniline, has been used to determine theequilibrium constant for solvent reorganization around the proton in mixtures ofvarying composition of water with acetic acid. In all the mixtures used, theself-ionization of the acetic acid was suppressed. In contrast to mixtures of waterwith the related ethanol or acetone, this equilibrium is shifted more toward thewater-solvated species as the mole fraction x 2 of the cosolvent increases. TheGibbs energy of transfer of protons from water into the mixture ΔG o t (H+) can bederived with the aid of this equilibrium constant for the solvent reorganization.Using ΔG o t (H+), ΔG o t (i) for i denoting anions and other cations can be evaluated.In comparison the ΔG o t (i) for cations have lower negative values than when eitherethanol or acetone is added to water. Correspondingly, for halide anions, thepositive ΔG o t (i) with added acetic acid are rather less than is found with eitherethanol or acetone added. The influence on the ion-solvent interaction of bothelectron withdrawing hydroxy and carbonyl groups in acetic acid may beresponsible for this. Although ΔG o t (i) for C10− 4 and Re0− 4 are also positive, both picrateions and OH− give negative values with acetic acid added to water. With picrateions, the hydrophobic effect of the carbon ring produces stabilization in themixture relative to water. With OH−, complete conversion to acetate anionsoccurs. As is found with other cosolvents, the contribution of the charge onacetate anion to ΔG o t (CH3COO−) is found to increase as x 2 rises. The aciddissociation constant K a for acetic acid is found to decrease slowly as x 2 rises to0.5, followed by a rapid decrease for x 2 greater than 0.7 where dimerization ofacetic acid occurs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005102517584
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  • 3
    Electronic Resource
    Electronic Resource
    Solubilities in aqueous mixtures oft-butanol andtrans-dichlorotetra(3-alkylpyridine) cobalt(III) hexachlororhenate(IV): Gibbs energies of transfer of the complex cations (1993)
    Springer
    Journal of solution chemistry 22 (1993), S. 883-894 
    Details
    ISSN: 1572-8927
    Keywords: Solubilities ; cobalt(III) complexes ; Gibbs energies of transfer ; solvolysis rates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The solubilities of the hexachlororhenate(IV) salts of the complex cations trans-[Co(3Mepy)4Cl2]+ and trans-[Co(3Etpy)4Cl2]+ have been determined in water+t-butyl alcohol mixtures. By reference to the solubilities of Cs2ReCl6 and the Gibbs energies of transfer of Cs+ from water into water+t-butyl alcohol mixtures, ΔG t o (Cs+), ΔG t o [Co(3Mepy)4Cl 2 + ] and ΔG t o [Co(3Etpy)4Cl 2 + ] are calculated. These latter values, when introduced into the equation for a free energy cycle applied to the process of the initial state going to the transition state for the solvolyses of these two cations, produces values for ΔG t o [Co(3Mepy)4Cl2+*] and ΔG t o [Co(3Etpy)4Cl2+*] for the Co3+ cations in the transition state. These values are compared with (ΔG t o (i) for i=[Co(Rpy)4Cl2]+, [Co(Rpy)4Cl]2+*, [Coen2XCl]+ and [Coen2X]2+* to investigate the influence of the hydrophobicity of the surface of the complex on its stability in the mixtures. ΔG t o (i) (solvent sorting) are compared with ΔG t o (i) (TATB).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00646600
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  • 4
    Electronic Resource
    Electronic Resource
    Kinetics of the solvolysis oftrans-dichlorotetra-(4-t-butylpyridine)-cobalt(III) ions in water +t-butyl alcohol mixtures (1990)
    Springer
    Journal of solution chemistry 19 (1990), S. 1073-1084 
    Details
    ISSN: 1572-8927
    Keywords: Solvolysis ; kinetics ; mixtures of water+cosolvent
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Rates of solvolysis of the complex cation [Co(4tBupy)4Cl2]+ have been determined in mixtures of water with the hydrophobic solvent, t-butyl alcohol. The solvent composition at which the extremum is found in the variation of the enthalpy ΔH* and the entropy ΔS* of activation correlates well with the extremum in the variation of the relative partial molar volume of t-butyl alcohol in the mixture and the straight line found for the variation of ΔH* with ΔS* is coincident with the same plot for water + 2-propanol mixtures. A free energy cycle is applied to the process initial state (C n+) going to the transition state [M(n+1)+...Cl−] in water and in the mixture using free energies of transfer of the individual ionic species, ΔG t o (i), from water into the mixture. Values for ΔG t o (i) are derived from the solvent sorting method and from the TATB/TPTB method: using data from either method, changes in solvent structure on going from water into the mixture are found to stabilize the cation in the transition state, M(n+1)+, more than in the initial state, C n+. This is compared with the application of the free energy cycle to the solvolysis of complexes [Co(Rpy)4Cl2]+ and [Coen2LCl]+ in mixtures of water with methanol, 2-propanol or t-butyl alcohol: the above conclusion regarding the relative stabilization of the cations holds for all these complexes in their solvolyses in water+alcohol mixtures using values of ΔG t o (Cl−) from either source.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00649452
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  • 5
    Electronic Resource
    Electronic Resource
    Growth and protein production kinetics of a murine myeloma cell line transfected with the human growth hormone gene (1991)
    Springer
    Cytotechnology 5 (1991), S. 223-231 
    Details
    ISSN: 1573-0778
    Keywords: cell culture ; kinetics ; Ig promoter/enhancer ; plasmacytoma ; recombinant protein production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A model mammalian cell system for the production of recombinant proteins was investigated. Murine myeloma cells which had lost the ability to produce both heavy and light chain immunoglobulin molecules were transfected with a vector containing the immunoglobulin heavy chain promoter and enhancer elements linked to the human growth hormone gene. The growth kinetics of G32, a clonal isolate, were found to be similar to both the parent myeloma and hybridomas. However, production of hGH by G32 was growth associated, rather than as a secondary metabolite as is the case for hybridomas. In addition, G32 produced hGH at molar levels greater than most hybridomas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00556292
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