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  • 1
    Electronic Resource
    Electronic Resource
    Synthesis of Homo- and Hetero-Bimetallic Complexes Containing the Ni(C6F5)2 Moiety - Crystal Structure of [(C6F5)2Ni(μ-SPh)2Pd(dppe)] (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1199-1204 
    Details
    ISSN: 1434-1948
    Keywords: Organometallic compounds ; Nickel complexes ; Crystal structures ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The compound cis-[Ni(C6F5)2(PhCN)2] has been used as the starting material for the preparation of the bimetallic complexes [(C6F5)2Ni(μ-X)2Ni(C6F5)2]2- (X = SCN, OCN, N3), [(C6F5)2Ni(μ-SCN)2Pd(C6F5)2]2-, [(C6F5)2Ni(μ-NCS)2Pd-(dppe)] [dppe = 1,2-bis(diphenylphosphanyl)ethane], and the trimetallic[(C6F5)2Ni(μ-NCS)2Pd(μ-SCN)2Ni(C6F5)2]2-. The mononuclear compounds [(C6F5)2NiLX] (L = PPh3, P(C6H4MeO-p)3; X = SCN, OCN) are obtained by reaction between [(C6F5)2Ni(&μ-X)2Ni-(C6F5)2]2- and L. The treatment of cis-[Ni(C6F5)2(PhCN)2] with [M(SAr)2(dppe)] leads to the formation of the arylthiolate complexes [(C6F5)2Ni(μ-SAr)2M(dppe)] (Ar = Ph, C6H4Me-p, C6H4NO2-p; M = Ni, Pd, Pt). The X-ray diffraction study of [(C6F5)2Ni(μ-SPh)2Pd(dppe)] shows that both metal atoms, Ni and Pd, are coordinated in a slightly distorted square-planar geometry and the μ-thiolato groups are in the syn conformation.
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  • 2
    Electronic Resource
    Electronic Resource
    Nature et stabilité des complexes métalliques de cryptands dinucléants en solution. I. Polyazapolyoxa macrotricycle cylindrique et monocycle constitutif (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 456-464 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nature and Stability of Some Metallic Complexes of Dinucleating Cryptands in Solution. I. A Polyazapolyoxa Cylindrical Macrotricycle and its Monocyclic SubunitpH-metry and UV spectrophotometry were used to study the complexing properties of the cylindrical macrotricycle, 1,7,13,19-tetraaza-4,16-dioxa-10,22,27,32-tetraoxatricyclo[17.5.5.5]tetratriacontane (1) and of its constitutive monocyclic subunit, 1,7-diaza-4,10-dioxacyclododecane (2) with some transition and heavy metal cations (Cu2+, Co2+, Ni2+, Zn2+, Cd2+, Pb2+, Ag+), in aqueous medium 0.1M Et4NClO4, at 25°. The protonation constants of the ligands as well as the nature and the stabilities of the complexes formed in the pH-regions studied were determined. The tricycle 1 only formed dinuclear M2L complexes with Cu2+, Zn2+, and Ag+, accompanied in the latter case by a protonated mononuclear MLH species, and with Cu2+ and Zn2+ at high pH-values by dinuclear hydroxo complexes. Only mononuclear complexes were evidenced with the other cations, ML being accompanied either by protonated or hydroxy mononuclear species. The mononuclear complexes of 1, when they existed, were more stable than the corresponding complexes of 2, except for cobalt which formed complexes of comparable stability with both ligands. In the other cases (Cd2+, Pb2+, Ag+), the stability differences between the complexes of 1 and 2 increased with the size of the cation.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19850680219
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  • 3
    Electronic Resource
    Electronic Resource
    Nature et stabilité des complexes métalliques de cryptands dinucléants en solution. III. Le monocycle [22]-Py2N4 (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 840-845 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nature and Stability of Some Metallic Complexes of Dinucleating Cryptands in Solution III. The Monocycle [22]-Py2N4The nature and stability of complexes formed by a new 22-membered monocycle L = [22]-Py2N4 with the cations Mn+ = Cu2+, Co2+, Ni2+, Zn2+, Cd2+, Pb2+, and Ag+ have been determined in aqueous solutions (0.01M NaClO4, 25°) by pH-metry and also, for the copper system, by UV-absorption spectrophotometry. The stepwise protonation constants of the four amine functions of L were 9.1, 8.3, 7.1 and 3.7 logarithms units, respectively. No evidence was found for the protonation of the two pyridine nitrogen atoms. Mononuclear complexes MLn+ were identified in all systems investigated, but the dinuclear species M2L2n+ were only found with Cu2+ and Ag+. The logarithms of the overall stability constants for the copper and silver complexes are CuL2+, 12.9; Cu2L4+, 18.6; Agl+, 6.3; Ag2L2+, 10.9, respectively. Mononuclear hydroxy species MLOH(n-1)+ were identified in all systems except those of copper and silver. No dinuclear hydroxy complexes were detected. The complexing properties of L are compared to those of the large and less rigid bis-dien.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19850680404
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  • 4
    Electronic Resource
    Electronic Resource
    Water-insoluble dextrans by grafting, 2Part 1: cf.3.. Reaction of dextrans with n-alkyl chloroformates. Chemical and enzymatic hydrolysis (1985)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 186 (1985), S. 17-29 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: This work deals with the modification reaction of dextran with ethyl and butyl chloroformate using tertiary amines as catalyst/acceptor systems and the DMF/LiCl system as solvent. The structure of the resulting polymers was determined by means of IR, 1H and 13C NMR spectroscopy as well as by chemical analyses. The reaction rate was found to increase in the following order: N,N′-dimethylaniline 〈 pyridine 〈 triethylamine. The presence of cyclic carbonates was observed when triethylamine was used as catalyst. A linear dependence of the reaction rate on polymer and pyridine concentrations and a more complex dependence on the n-alkyl chloroformate concentration were found. Reaction rate and yield decrease with increasing amount of LiCl in the solvent medium and increase with increasing chain length of the n-alkyl chloroformate. The activation energy was found to be 64 kJ/mol (15,3 kcal/mol). The equilibrium water content (EWC) values decreases progressively when either the content of carbonate groups or the side chain length increases. The hydrolysis in the heterogeneous phase showed that the time required for the polymer solubilization is dependent upon the nature of the carbonate groups, the temperature as well as the pH value of the medium. Dextranase was found to be inactive in the hydrolysis of water-insoluble modified dextrans. However, the hydrolysis takes place when water-soluble modified dextrans were used.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1985.021860103
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  • 5
    Electronic Resource
    Electronic Resource
    Release of sodium salicylate from vinyl alcohol/n-alkyl vinyl carbonate copolymers (1985)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 186 (1985), S. 2117-2123 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: This study is concerned with the sodium salicylate release from thin discs of vinyl alcohol/n-alkyl vinyl carbonate copolymers into an aqueous medium under sink conditions. The drug content of the disc decreases with pseudo-first order rate initially, whereas the drug quantity released is proportional to the square root of time. Data analysis supported the latter treatment, which is in agreement with the diffusional matrix model and invalidates the pseudo-first order assumption. The diffusion coefficient D of vinyl alcohol/ethyl vinyl carbonate copolymers decreases with increasing ethyl vinyl carbonate content whilst D increases as both sodium salicylate concentration and temperature increase. The activation energy of diffusion was found to be 46,03 kJ/mol (11,00 kcal/mol).
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1985.021861015
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  • 6
    Electronic Resource
    Electronic Resource
    On the existence of shock fronts for a Burgers equation with a singular source term (1998)
    Chichester, West Sussex : Wiley-Blackwell
    Mathematical Methods in the Applied Sciences 21 (1998), S. 1107-1113 
    Details
    ISSN: 0170-4214
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: In this paper we consider the Cauchy problem for the equation∂u/∂t + u ∂u/∂x + u/x = 0 for x 〉 0, t ≥ 0, with u(x, 0) = u0-(x) for x 〈 x0, u(x, 0) = u0+(x) for x 〉 x0, u0-(x0) 〉 u0+(x0). Following the ideas of Majda, 1984 and Lax, 1973, we construct, for smooth u0- and u0+, a global shock front weak solution u(x, t) = u-(x, t) for x 〈 φ(t), u(x, t) = u+(x, t) for x 〉 φ(t), where u- and u+ are the strong solutions corresponding (respectively) to u0- and u0+ and the curve t → φ(t) is defined by dφ/dt (t) = 1/2[u-(φ(t), t) + u+(φ(t), t)], t ≥ 0 and φ(0) = x0.© 1998 B. G. Teubner Stuttgart - John Wiley & Sons, Ltd.
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  • 7
    Electronic Resource
    Electronic Resource
    Use of the UASB reactor for the anaerobic treatment of stillage from sugar cane molasses (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 1710-1716 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The feasibility of applying the UASB concept for the anaerobic treatment of stillage of distilleries in the sugar producing area of Argentina was subject to study. Results obtained in a 100-L UASB reactor treating stillages with COD values between 35 and 100 g COD/L are presented. Loading rates of up to 24 g COD/L/day were applied with an average COD removal of 75% and a biogas production of more than 9 L/L/day, with an average methane content of 58%. The settling velocity distribution of sludge particles would indicate a good formation of biomass pellets. System interruptions of months without feed and at ambient temperature (20-24°C) were well tolerated.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260271212
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  • 8
    Electronic Resource
    Electronic Resource
    Critical properties, potential force constants, and structure of organic molecules (1985)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 31 (1985), S. 1563-1565 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690310920
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  • 9
    Electronic Resource
    Electronic Resource
    Hydrolysis and Condensation Reactions of Transition Metal Alkoxides: Calorimetric Study and Evaluation of the Extent of Reaction (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1115-1127 
    Details
    ISSN: 1434-1948
    Keywords: Sol-gel process ; Polymers, inorganic ; Transition metal alkoxides ; 17O-NMR spectroscopy ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The behavior of titanium and zirconium alkoxides towards complexation and water addition is analyzed through water titration and calorimetric experiments. A simple model is presented, which allows evaluation of the mean hydrolysis and condensation constants, Kh and Kc, of both pure and complexed transition metal alkoxides in the sol state, through the analysis of consumed water versus initial hydrolysis ratio curves. These constants allow comparison of the extents of the hydrolysis and condensation reactions for sols obtained from several alkoxide precursors. The complexation ratio only affects the condensation constant Kc, whereas the hydrolysis constant Kh remains unchanged. Analysis of the Kh/Kc ratios has shown that in the sol state, silanol Si-OH groups are more stable than the Ti-OH or Zr-OH groups. Moreover, this study has shown that the proton concentration not only affects the kinetics, but also the final composition of the system. Calorimetric studies of the complexation and hydrolysis/condensation reactions have highlighted the role of coordination unsaturation of the transition metal alkoxides in the exothermicity of these reactions, clearly demonstrating that coordination unsaturation is the driving force behind the reactivity of these alkoxides towards nucleophilic species (e.g. water, complexing ligands, polar solvents).
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  • 10
    Electronic Resource
    Electronic Resource
    Modeling of biomass productivity in tubular photobioreactors for microalgal cultures: Effects of dilution rate, tube diameter, and solar irradiance (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 58 (1998), S. 605-616 
    Details
    ISSN: 0006-3592
    Keywords: solar irradiance ; tubular photobioreactor ; microalgal culture ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A macromodel is developed for estimating the year-long biomass productivity of outdoor cultures of microalga in tubular photobioreactors. The model evaluates the solar irradiance on the culture surface as a function of day of the year and the geographic location. In a second step, the geometry of the system is taken into account in estimating the average irradiance to which the cells are exposed. Finally, the growth rate is estimated as a function of irradiance, taking into account photoinhibition and photolimitation. The model interconnects solar irradiance (an environmental variable), tube diameter (a design variable), and dilution rate (an operating variable). Continuous cultures in two different tubular photobioreactors were analyzed using the macromodel. The biomass productivity ranged from 0.50 to 2.04 g L-1 d-1, and from 1.08 to 2.76 g L-1 d-1, for the larger and the smaller tube diameter photobioreactors, respectively. The quantum yield ranged from 1.1 to 2.2 g E-1; the higher the incident solar radiation, the lower the quantum yield. Simultaneous photolimitation and photoinhibition of outdoor cultures was observed. The model reproduced the experimental results with less than 20% error. If photoinhibition was neglected, and a growth model that considered only photolimitation was used to fit the data, the error increased to 45%, thus reflecting the inadequacy of previous outdoor growth models that disregard photoinhibition. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 58: 605-616, 1998.
    Additional Material: 9 Ill.
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