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  • Inorganic Chemistry  (6,777)
  • Industrial Chemistry
  • 1985-1989  (3,587)
  • 1950-1954  (2,931)
  • 1915-1919  (1,735)
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  • 1
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The chlorination of an alumina with BET surface area of 100 m2/g has been studied in situ by transmission IR measurements at about 670 K. The chlorinating gases consisting of Cl2 and CO were employed individually and in equimolar proportion. The IR results do not reveal the presence of a phosgene surface species which could support the only mechanism proposed so far to explain the chlorination. A detailed alternative reaction mechanism is suggested for the high temperature chlorination reaction, taking into account the IR results, together with the known electron donor-acceptor properties of the activated alumina and the reaction gases: Cl2 molecules accept electrons from oxide ions with a lower coordination number on the alumina surface, leading to the formation of Cl-and Oad. While Cl- yields AlCl3, Oad reacts further with CO producing CO2.
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  • 2
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The vapour phase hydrogenation of 1,3-cyclo-octadiene (COD) over Pd on alumina has been studied in the gas phase, using a recycle reactor. The dependences of COD hydrogenation rates and those of the consecutive cyclo-octene (COE) hydrogenation on the reaction conditions are well described by a model which takes into account mass transfer in the porous layer of palladium. The kinetics of the COE hydrogenation is of a Langmuir-Hinshelwood type. The hydrogenation of COD is of first order with respect to hydrogen. The reaction order with respect to COD is -0.15. If the catalyst surface is completely covered by COD, the hydrogenation of COE is totally suppressed. This indicates a much stronger adsorption of COD than of COE. Hydrogenation of COE can only occur in the innermost part of the pores when the transport of COD by diffusion is insufficient to supply the entire active surface of the catalyst. This happens if the ratio PH2/PCOD exceeds 2/ϕ2 with ϕ being the Thiele's modulus. This relationship permits a simple evaluation of the effective diffusion coefficient in the porous Pd-layer.
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  • 3
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In the course of polymerization in homogeneous systems, the viscosity of the reaction mass increases by several orders of magnitude. The viscosity increase is affected by reaction conditions, concentration and properties of the formed polymer. Empirical correlations for homogeneous and heterogeneous polymerizations are given. Viscosity significantly affects the polymerization kinetics as well as heat, mass and momentum balances of the polymerization reactor. The influence of viscosity and its increase on conductive heat transfer, stirrer power input and cooling capacity, molecular diffusion and mass transfer coefficients, mixing time and residence time distribution in homogeneous and heterogeneous polymerizations in stirred tank and tubular reactors is reviewed.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 103-109 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: During the past decade, the sintering of model supported metal catalysts, i.e. catalysts consisting of metal deposited on very thin and flat oxide films, has been intensively investigated by transmission electron microscopy. In the current paper, a mathematical model, based on an atomic migration mechanism, for the sintering of these catalysts is presented. The predictions of the model, based on Monte Carlo simulations, are in very good agreement with the experimental observations, i.e. phenomena such as ‘apparent’ particle migration, splitting and neck formation between particles are predicated by the model.
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  • 5
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The prediction of leak areas in pressure vessels is an important objective in the safety analysis of chemical plants. Using suitable design rules, a leak-before-break behaviour can be achieved. This contribution outlines a procedure for the leak-before-break design of nozzle attachments and the determination of the size of the corresponding opening area. In addition, K1-factors and leak areas for a number of nozzle geometries have been calculated and plotted.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 155-161 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The conversion of methanol over zeolite H-T was investigated in a fixed bed reactor. H-T was prepared from Na-T by ion exchange with HCl and NH4Cl solutions. The HCl solution caused appreciable dealumination. High yields of ethene were obtained with NH4Cl exchangeed zeolites Na-T with 45% decationization, high proprne yields with low HCl or NH4Cl Exchanged catalysts. Low methanol partial pressures and short residence times favoured the formation of lower olefins. Lowest coking rates were observed at a reaction temperature of 693 K. The catalytic activity decrased slowly with the number of reaction/regeneration cycles. The distribution of procucts 〉 C2 could be described by the most probable distribution of Schulz and Flory.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 188-195 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Collection efficiency and pressure loss of a venturi scrubber can usually be determined from the calculation models of Barth and Calvert. However, this only leads to reasonable results if the droplets are uniformly distributed throughout each cross-section of the washing zone. In this work, a two-zone models is developed which allows the calculation of the venturi scrubber at operating conditions with a non-uniform droplet distribution. The scrubber geometry is also taken into account. A venturi scrubber was developed on the basis of this new model. Its energy consumption is significantly lower than the well-Known optimum characteristic of Wicke and Holzer. For ideal operating conditions, a new optimum characteristic is given which should be the aim of future optimizations.
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  • 8
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The influence of turbulence on local heat and mass transfer is systematically analyzed. Essential prerequisite is the availability of measurement methods, based on convective mass transfer, which allow the visualization of heat and mass transfer distributions. The results show that, even at low turbulence intensities, the flow and transport phenomena are decisively influenced by the specific design of turbulence grids and the orientation of the grid wires with respect to the stagnation line. Thereby, two different flow mechanisms occur which may interact. The anisotropy of grid turbulence leads to the “wire-gap effect” depending on the actual position of the grid wires in relation to the stagnation line. The other mechanism is based on the wavy wake velocity distribution behind screens and grid which, in conjunction with the centrifugal instability of stagnation flows, may lead to longitudinal vortices. The results indicate why turbulence has not been sufficiently considered in the available (semi-) empirical correlations. Information needed for an accurate prediction of heat and mass transfer in turbulence flows is discussed.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 205-212 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A circular loop reactor was built for application to a heterogeneous liquid-liquid reaction. In order to investigate the dispersion behaviour of droplets in the reactor, basic experiments were performed using a number of liquid-liquid dispersions. Droplets discharged form the impeller region were found to grow due to coalescence in the circulation region. Mean droplet diameter decreased exponentially with elapsing time. An expression correlating the steady-state mean droplet diameter with the operating conditions was derived. Moreover, the transition time required for the droplet diameter to reach the equilibrium value was determined and correlated with the operating conditions.
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  • 10
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The explosion behaviour of CH4/air mixtures inside a closed 0.065 m3 spherical and a 1 m3 cylindrical vessel was investigated to determine the effect of turbulence on the structure and propagation rate of transient turbulent flames for different initial turbulence levels generated by 4 ventilators installed inside the equipment. Laser-Doppler and hot wire anemometry were used to measure the turbulent motion. It was found that fairly uniform turbulence could be achieved in the central zones of the vessels and that the RMS-values of flow velocity were proportional to the ventilator speed. The evaluation of burning velocity from the pressure/time records showed that, starting from an initial burning velocity which depends on the initial turbulence level, the flame accelerates as a result of pressure, temperature and turbulence effects. Maximum burning velocity coincides with the inflexion point of the pressure/time curve, and is followed by a rapid deceleration of the flame front. A linear relationship between burning velocity and measured RMS-velocity is recognized in the observed range of RMS-values.
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  • 11
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Film theory under consideration of one-sided diffusion is a satisfactory basis for the calculation of vapour condensation from a flowing turbulent mixture with non-condensable gases. At atmospheric pressure and low condensate flow rates, coefficient equations for smooth tubes are used as a rule. At higher pressures and thus, at higher temperatures and gas densities, there are additional parameters. For instance, non-ideal behaviour of the gas phase or the surface roughness affects the condensation process. These parameters were examined in a test plant under variation of pressure, steam concentration and temperature in a vapour/air mixture. At pressures of up to 21 bar, the Reynolds number of the gaseous phase reaches a maximum value of 128 000 and of 720 for the condensed phase. After description of the test facility, the experimental results are explained and discussed. It is shown that the experimental results are not in a good agreement with the common calculating methods. Taking into account the non-ideal behaviour of the steam/air mixture and the roughness of condensate surface by using a friction factor ξr, all the results could be calculated with an accuracy of ± 20%. This was achived with a modification of the coefficient equation of Gnielinski [1] and by using the equation of Andreussi [2] for the friction factor of a cocurrent annular flow. With respect to one-sided diffusion, the film theory is still applicable. The described method for the determination of local transfer coefficients includes the common calculating method. It represents an extension of the general validity of the film theory.
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  • 12
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Studies of flow characteristics and residence time distribution, (RTD), have been undertaken in a range of geometrically similar, laboratory nozzle-type reactors. High-speed cine-photography was employed to record the complex phenomena of liquid mixing in the reactor and also to record on film the colour of an injected tracer solution leaving in the effluent. A novel atomic absorption spectrophotometric (AAS) technique was applied to transform the results of the latter film into response curves. This technique provide detailed quantitative data on the residence time distributions (RTD) for different feed rates. A multiparameter model, comprising a network of CSTR's and plug flows, was developed to simulate the experimental response data. Good agreement was obtained between model predictions and experimental results. The experimental technique and theoretical approach are recommended for analyzing the flow patterns and mixing mechanisms in such reactors.
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  • 13
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Heat transfer and fluid mechanical data were computed for laminar channel flows containing strong longitudinal vortex pairs. The strong vortices are generated by thin delta wings and delta winglet pairs of low aspect ratios and large angles of attack. These wings are attached to the channel walls. The data show that longitudinal vortices cause high local peaks in heat transfer and marked increases in the overall channel heat transfer. These increases occur over a wide region of channel wall, compared to the vortex generating wing area. The results are of special interest for compact heat exchangers. The heat transfer enhancement allows a considerable reduction in the heat transfer area which, in turn, reduces the manufacturing and operating costs.
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  • 14
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An independent preliminary mechanistic prediction method for leakage rates through small slit-shaped through-wall cracks, based on coupled pressure drop and (critical) mass flux calculation is presented. The predictions are verified against initially subcooled liquid refrigerants and water data collected during experiments in real and model cracks in a wide range of parameters. The achieved accuracy of prediction is already comparable to that of the experimental results. Further model modifications are put forward.
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  • 15
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 333-339 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The most important investigations on liquid weeping and entrainment in plate columns with downcomers are reveiwed. The formulae for calculating column plate efficiency under conditions of liquid weeping and entrainment have been derived on the basis of mass balance equations. The presented model is a generalization of the models of AIChE and Colburn. Sample results are shown graphically. The effect of liquid entrainment on tray efficiency predicted by the model is in agreement with experimental data of FRI.
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  • 16
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 17
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Mean droplet diameter of the dispersed phase in pulsed plate extraction columns was measured for binary and ternary systems. A change in the droplet size in the presence of solute, dependent on such factors as the direction of mass transfer, droplet size in the binary system, radio of diffusion coefficients, viscosity of the continuous phase, interfacial tension and driving force for extraction was observed. Two new empirical correlations of mean droplet sizes in mass transfer conditions are proposed. These correlations have been successfully applied to other extraction columns.
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  • 18
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper considers the dynamic performance of instruments in control systems. Errors connected with transient measurements are discussed. It is shown that it is not always proper to assign common statistical properties to these dynamic errors. Emphasis is placed on temperature sensors. Common industrial thermometers are described and factors affecting their response discussed. An a-priori dynamic performance prediction procedure is presented. This permits preinstallation estimation of response characteristics of sensors used in industrial processes. Sensors in service also require performance assessment since they can deteriorate with use. In-situ testing is useful for this purpose and a recently develolped procedure is described.
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  • 19
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The principle of ultrasonic spectrometry is based on the measurement of the ultrasonic extinction caused by the presence of particles. From measurements at different frequencies and with the knowledge of the ultrasonic extinction cross section of the particles, a system of linear equations can be established and solved to obtain the particle size distribution and particle concentration. With an experimental apparatus covering the frequency range from 1.7 MHz to 81 MHz, particles ranging from 20 to 1000 μm in diameter may be analyzed. The measurements can be carried out with particle concentrations as high as 10% by volume.
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  • 20
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This study describes the gas and liquid distributions in a column with structured packings. The column is 0.5 m in diameter. It is equipped with a total of 1289 detectors in the top and bottom cross-sections. These detectors provide a detailed picture of the gas and liquid flows through elements of only 25 × 25 mm2. The maldistribution in the gas bulk flow is negligible. Only the observed wall can contribute to malperformance. The gas flows in parallel to sheet orientation, thus introducing a radial transport. Together with the change in the orientation of subsequent packing elements, this results in good gas mixing. It was observed that the liquid wall flow rate decreases when the gas velocity exceeds 1.7 m/s. Up to the loading point, the maldistribution of the liquid is constant. Above this point, the equality of the distribution deteriorates rapidly, due to the occurrence of large-scale liquid segregation.
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  • 21
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Grade efficiencies must be measured in order to characterize particle collection in cyclones. For real, irregularly shaped partcles, the grade efficiencies depend on the shape and orientation of the particles and the flow around them. Therefore, the collection characteristics of cyclones should be defined in relation to spherical particles. Deviations occurring on the use of real, irregularly shaped dusts can then be attributed to a material influence. A fast and accurate measuring technique to determine the collection characteristic for spherical particles is described, followed by the presentation of results of extensive investigations on small model cyclones. A similarity relationship is presented. The validity of this relationship was confirmed by investigations with similar, larger cyclones.
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  • 22
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Effective interfacial area a and volumetric liquid-side mass transfer coefficient kLa of an RTL contactor were obtained at different stirring speeds by absorption of oxygen from air into 0.8 kmol/m3 sodium sulphite solution, in the presence of Co++ ions. The values of a and kLa ranged from 80 to 150 m2/m3 and 0.0003 to 0.00053 s-1, respectively, when stirrer speed was increased from 8 to 40 rpm. When kL alone was evaluated, it was found to be practically constant, irrespective of stirring speed.
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  • 23
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The absorption of nitric oxide (NO) in phosphoric acid esters and polyethylene glycol ethers which contain cupric halides has been investigated. Due to high solubility of cupric halides and high equilibrium constants of formed nitrosyl complexes, the effective solubility of nitric oxide can be enhanced to about 100-fold its solubility in the salt-free organic liquid which itself amounts to only about 5-fold the NO-solubility in water. Calculations taking into account flue gas conditions indicate that the required gas-liquid ratio in industrial absorption processes will lie in the normal range of flue gas scrubbing processes, namely in the region of 400:1 to 1000:1 in volume. Thus, such a reversible absorption process could a viable alternative to SCR-processes in flue gas denitrification.
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  • 24
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: It is shown in this report that, under certain conditions, cleaning of exhaust air by absorption presents an interesting alternative to the existing methods. In particular, this process can be used with advantage for small quantities of exhaust air, high and strongly fluctuating solvent concentrations and solvent mixtures such as those occurring in batch operation. A washing agent was employed which had not been previously used for this purpose. Its properties, which were investigated in the laboratory, were confirmed during a 15-months' trial period in a semi-industrial plant. The process and plant were optimized for practical use. Through its option of solvent recovery from exhaust air, this physical absorption process contributes to environmental control.
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  • 25
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Depressurization of a pressure vessel, containing a liquid or a gas is limited by the maximum possible mass flux. This flux occurs at a certain drop in pressure. The ratio of ambient pressure to that inside the vessel must be less than a certain critical value. The critical pressure ratio depends on the thermodynamic state of the fluid inside the vessel and on the geometry of the outlet cross-section. The outlet can be a pipeline, a safety valve or a rupture disk. The results of known theoretical and experimental work are presented. In previous experiments, saturated liquids, two-phase flows or pure vapours were examined. In order to predict the critical pressure ratio, certain assumptions are necessary. These are derived for three well-defined cross-sections of the vessel outlet.
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  • 26
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Anaerobic fermentation of molasses distillery slops to biogas was carried out with the aid of an adapted and selected anaerobic mixed culture. Two different types of fermenters were used, namely an agitated pretreatment fermenter and a column fermenter with glass rings as carriers for micro-organisms. The production of biogas in both fermenters amounted to between 0.6 and 0.8 dm3/g COD. The aerobic pretreatment of distillery slops by T. fermentans, yeast during a 4 to 6 h period allows a high reduction of COD in the subsequent anaerobic phase of the process. After treatment of the distillery slops by T. fermentans, it was possible to convert between 85 and 93% of the organic matter to methane. Conversion was about 93% with loading rate of 25g COD/litre day.
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  • 27
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Secondary nucleation in industrial crystallizers depends on both supersaturation and mechanical stress by stirring. Most models which consider mechanical stress assume that nucleation is proprotional to the energy transferred to the crystals during collisions. This is not based on any physical relationship and, in addition, the models do not satisfactorily reproduce the experimental results. Own model, based on the theory of Hertz/Huber, which accounts for the stress of the crystals caused by impact, gave better results. This well-known and proven theory allows the calculation of the volume abraded during collisions between crystals and stirrer or walls. Introducing a nucleate efficienncy, the effect of mechanical stress on the rate of secondary nucleation, due to stirring intensity and crystallizer size, can be determined.
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  • 28
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Distillation has been, up to now, the standard method for separating fluid mixtures in the process industry and the consensus is that it will remain so for years to come. The only disadvantage of distillation is its high energy requirement. In the following, it will be demonstrated on the example of an ideal ternary mixture, how the energy requirement of distillation process can be reduced. Very effective are some modifications of single columns, optimization of column sequences and direct or indirect column coupling. It will be shown that, just by column coupling, the energy requirement can be reduced to a third.
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  • 29
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 200-204 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A model of floc destruction resulting form mass forces in a centrifugal field is postulated and its validity examined. This model is to be regarded as a supplement to the existing shear-loading disagglomeration models. In order to verify this additional floc disintegration mechanism, appropriate investigations were carried out with flocculated suspensions of silica and Hamburg dock sludge. As a result, in addition to floc disintegration by shear forces within a turbulent flow and in the centrifuge inlet, the existence of another mechanism was demonstrated. This consists in the floc destruction in a centrifugal field where particles in excess of a certain size, or specifically heavier components, are preferentially torn out of the floc. This floc disintegration by mass forces can lead to a classification effect in centrifuges which also subject the flocs to instant high centrifugal forces.
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  • 30
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 31
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 269-273 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 7 Ill.
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  • 32
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A cubic equation of state is modified in such a way that prediction of PVT data from 40 model compounds, typical of coal oil, becomes possible with an absolute mean deviation of less than 2% for saturated liquid volumes and vapour pressures 〉 1 bar. Additional correlations for binary interaction parameters are obtained by an optimization procedure using vapour-liquid euilibrium (VLE) data from known heavy hydrocarbon liquid/light gas systems. When the modified equation is applied to coal-derived liquids, only specific gravity and boiling analysis data of the coal liquids are required, primarily in order to determine the equation-of-state parameters. The proposed equation is shown to allow a good prediction of VLE data for systems consisting of wide-boiling-range coal oils and light gases. Experimental values were obtained at elevated temperatures and pressures with a circulation flow apparatus.
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  • 33
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: To improve the rate of convergence of random search optimization procedures, the incorporation of a gradient-oriented one-dimensional search is investigated. With this modification to the random search procedure based on uniform sampling and region contraction [1], convergence to within 0.01% of the global optimum was obtained substantially faster for typical chemical engineering problems. It was also found that the reliability of obtaining the global optimum was improved.
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  • 34
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The knowledge of the heat transfer coefficient on the inner side of a heated vessel wall is of the utmost importance for the design of agitated vessels. In the case of large Reynolds numbers, the heat transfer is mainly determined by these numbers whereas, with small Reynolds numbers, the heat transfer is better described by considering the Grashof number. Investigations of heat transfer in agitated narrow vessels have shown that the height/diameter ratio exerts virtually no influence on the heat transfer when multi-impeller stirrers are used. The heat transfer to stirred suspensions can be described by relationships valid for liquids if the characteristic data of the liquid are replaced by those of the suspension and when the solids volume concentration is also taken into account. This relationship allows the heat transfer coefficient to be calculated for given solids volume concentrations of up to 60%.
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  • 35
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In order to achieve optimal energy-saving, load-dependent operation of rectification columns, development and implementation of model-based control concepts are necessary. This paper reports on the design and step-by-step testing of a state observer for the estimation of two state variables which cannot be measured directly, namely the vapour rate and the location of mass transfer zone (temperature front) in the stripping section of a production column. The procedure is described, and the relevant simulation and operation results are presented and discussed. Initial experience, gained when the concept was put into practical operation, is reported.
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  • 36
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Flow phenomena, local heat and mass transfer and pressure drop of corrugated passages in process equipment are examined. Based on a method for measuring local heat and mass transfer, developed in previous investigations, a procedure has been formulated for the determination of local heat and mass transfer in corrugated passages. Using the analogy between heat and mass transfer, this technique allows the determination of heat transfer distributions in any structures with high local resolution. The corresponding pressure drop is presented together with the local and integral heat and mass transfer of different structures. It is shown that differences in heat and mass transfer as well as in pressure drop are due to different flow phenomena which also characterize mixing behaviour.
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  • 37
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Crystallizer design has to take into account the physical and chemical properties of the solution and solids as well as the geometry, type and operating conditions of the crystallizer. The most important property of a crystallizing system is its solubility. High solubility leads to low relative supersaturation and large mean crystal size, and vice versa. High solubility systems can be sensitive to abrasion and attrition. For low solubility systems, mixing is crucial.
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  • 38
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Wall shear rate vectors in a bubble column and an airlift-loop reactor were measured using the limiting-current electrodiffusion technique. In connection with a new circular three-segment probe, the magnitudes and directions of shear rates were determined. The results for the bubble column are in good agreement with hot film-anemometry measurements in the same column. Moreover, the spiral flow structure, postulated in the shear-zone model of Franz, has been confirmed. In addition, the measuring technique was used to determine the flow structure in an airlift-loop reactor employed for the cultivation of animal cells. The region above the gas distributor of this fermenter has been identified as critical for mechanical damage to the cells.
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  • 39
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An experimental technique and evaluation method is described for the determination of local heat transfer coefficients in tubes or other ducts. By means of a rotary mixing valve, cold and warm fluid flows are mixed in order to generate an arbitrarily shaped but periodically oscillating inlet temperature profile at the test tube. The propagation of the fundamental harmonic oscillation from the fluid to the outer surface of the tube wall is calculated analytically. Comparison of fluid and wall oscillations yields the heat transfer coefficient to be measured. The inaccurate measurement of fluid bulk temperature in the centre of the cross-section is compensated by an additional correction. Experiments were carried out with turbulent water flow through a copper tube. Measured heat transfer coefficients were compared to values calculated using Hausen's equation and good agreement was obtained.
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  • 40
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Mass transfer data are presented for absorption of oxygen in a centrifugal film apparatus. The apparatus was designed to exclude the formation of foam by gas dispersion in liquid. Cells and micro-organisms are not subjected to high shear stress. Therefore, this equipment can be applied in fermentation processes. In the present work, experimental data and correlations were obtained on splitting of the liquid film and oxygen absorption into the film through a spiral ridge formed on the conical surface. The performance of the apparatus is found to be equivalent to those of other types of absorbers.
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  • 41
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    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 255-261 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The Carman-Kozeny equation is applicable in the viscous flow regime but, as the powder becomes finer, this equation fails. The controlling factor is the ratio of the hydraulic diameter to the mean free path of gas molecules (rH/λ) and, as this approaches unity, “slip flow” occurs. This effect increases with (a) increasing fineness, i.e. rH reduced, (b) decreasing porosity, i.e. rH reduced, and (c) decreasing pressure, i.e. λ increased. In order to account for the enhanced flow arising as a result of this failure, a second term is introduced into the equation and this includes an unknown “constant” (δK0/K), the coefficient of slip. It was considered probable that this so-called constant was a function of (rH/λ), and an attempt was made to investigate this relationship.
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  • 42
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A superposition of simple physical equations allows a satisfactory, comprehensive fluid dynamic description of jet-loop reactors in multiphase operation up to a dispersed phase hold-up of 15%. In the case of higher concentrations, there are further interactions which are not yet included in the model description. Apart from the drag coefficient of the single-phase jet loop, information on the particle swarm behaviour, i.e. on the slip velocity of the dispersed phase is required. Explicit formulation of the influence of the relevant geometrical parameters permits a reliable scale-up without additional adaptation parameters.
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  • 43
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: During molecular distillation in a falling film apparatus, temperature and concentration of the more volatile components undergo a marked decrease in axial and radial directions, due to the distillation in vacuo. The gradients produce changes in the rate of surface evaporation and separation efficiency along the flow path. A theoretical study of this problem is presented for binary mixtures. The respective differential equations for heat and mass transfer in the liquid film are solved numerically. As the results demonstrate, the aspect ratio of an apparatus should be large when a high separation is required and small when a high distillation rate is more important.
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  • 44
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Modelling of the kinetics of a 20-N hydrazine thruster is carried out by considering two different heterogeneous reaction channels for hydrazine decomposition to the intermediate ammonia. The parameters of the reactor model are estimated by making use of temperature profiles at the wall of the decomposition chamber. Simulated ageing of the catalyst revealed an increase of the rate of deactivation with increasing total firing time.
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  • 45
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 568 (1989), S. 8-21 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Na(V3-xNbx)Nb6O14  -  A Novel Oxoniobate with [Nb6O12] and [M2O9] ClustersGoldcolored single crystals and black powders of Na(V3-xNbx)Nb6O14 have been prepared by heating a pellet containing a mixture of NaNbO3, NbO2, NbO, VO2 and NaF or Na2B4O7 (as mineralizers) at 900°C in a sealed gold capsule. The analytically determined Nb : V ratio is 5 : 1 and means that x is about 1.5. The compound crystallizes in P63/m with a = 603.4(1), c = 1807.9(5) pm and Z = 3.The crystal structure can be described in terms of common close packing of sheets of O and Na atoms together with Nb6 octahedra. Characteristic building groups of the new structure type are [Nb6O12] clusters, [M2O9] clusters and NbO5 bipyramids. V atoms are distributed only on the positions of the Nb atoms within the trigonal bipyramids or the [M2O9] clusters. The [Nb6O12] clusters show characteristicaly short distances dNb-Nb = 279.4 and 281.3 pm, respectively. In the [M2O9] units, which are built from two MO6 octahedra that share a common face, V or Nb atoms form M-M dumbbells with dM-M = 255.9 pm. The electronic structure is discussed using Extended Hückel calculations.
    Notes: Goldgelb glänzende Einkristalle und schwarze Pulver von Na(V3-xNbx)Nb6O14 wurden durch Tempern eines zu einer Pille gepreßten Gemenges aus NaNbO3, NbO2, NbO, VO2 und NaF oder Na2B4O7 (als Mineralisatoren) bei 900°C in einem geschlossenen Goldrohr dargestellt. Das analytisch ermittelte Verhältnis Nb : V ist ungefähr 5 : 1, so daß x bei etwa 1,5 liegt. Die Verbindung kristallisiert in P63/m mit a = 603,4(1), c = 1807,9(5) pm und Z = 3.Die Kristallstruktur baut sich aus gemeinsam dicht gepackten Schichten von O-Atomen, Na-Atomen und Nb6-Oktaedern auf. Charakteristische Baugruppen des neuen Strukturtyps sind [Nb6O12]- und [M2O9]-Cluster sowie NbO5-Bipyramiden. Die V-Atome verteilen sich nur auf die Positionen der Nb-Atome in den trigonalen Bipyramiden und den [M2O9]-Cluster. Innerhalb der [Nb6O12]-Cluster liegen charakteristisch kurze Abstände dNb-Nb = 279,4 bzw. 281,3 pm vor. In [M2O9]-Einheiten, zwei über Flächen verknüpften MO6-Oktaedern, bilden V- und Nb-Atome M-M-Hanteln mit dM-M = 255,9 pm. Die Bindungsverhältnisse werden unter Zuhilfenahme von Extended-Hückel-Rechnungen diskutiert.
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  • 46
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    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 568 (1989), S. 29-34 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Ba5AlIr2O11: A New Compound with Iridium(IV, V)The hitherto unknown compound Ba5AlIr2O11 was prepared and investigated by X-ray technique (space group D2h16-Pnma, a = 18.8360; b = 5.7887; c = 11.1030 Å; Z = 4). Iridium has an octahedral coordination in each case two octahedra are connected by a plane. These double octahedra form with corner connected AlO4 tetrahedra [Ir2AlO11]10- units. Ba5AlIr2O11 is not related to the perovskite type compounds.
    Notes: Die bisher unbekannte Verbindung Ba5AlIr2O11 wurde dargestellt und die Kristallstruktur bestimmt (Raumgruppe D2h16-Pnma, a = 18,8360; b = 5,7887; c = 11,1030 Å). Iridium ist oktaedrisch koordiniert, je zwei Oktaeder sind flächenverknüpft. Je ein Oktaederdoppel bildet mit eckenverknüpften AlO4-Tetraedern eine [Ir2AlO11]10--Baueinheit. Ba5AlIr2O11 gehört nicht zu den Perowskitvarianten.
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  • 47
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Experiments about the Mixed Crystal Formation between Zincoxotantalates and -antimonates: ZnTa2-xSbxO6 and Zn4Ta2-xSbxO9In the area of substituted oxotantalates of zinc two new phases of the composition A: ZnTa1·8Sb0·2O6 and B: Zn4Ta1·2Sb0·8O9 were prepared and investigated by X-ray single crystal technique. A crystallizes with tetragonal symmetry (space group D4h14-P42/mnm, a = 4.7314; c = 9.2160 Å; Z = 2). B is monoclinic (space group C2h6-C2/c; a = 15.103; b = 8.839; c = 10.378 Å; β = 93.81°; Z = 8). A crystallizes with trirutile structure, although there is a small replacement of Ta5+ by Sb5+. B maintains the Zn4Ta2O9 structure. One of the point positions of the M5+ ions is occupied statistically by Ta5+/Sb5+ and Zn2+. B is a metastable compound.
    Notes: Im Bereich substituierter Oxotantalate des Zinks wurden zwei neue Phasen A: ZnTa1,8Sb0,2O6 und B: Zn4Ta1,2Sb0,8O9 an Einkristallen röntgenographisch untersucht. A kristallisiert tetragonal (Raumgruppe D4h14-P42/mnm, a = 4,7314; c = 9,2160 Å; Z = 2), B monoklin (Raumgruppe C2h6-C2/c, a = 15,103; b = 8,839; c = 10,378 Å; β = 93,81°; Z = 8). A kristallisiert trotz des geringen Ersatzes von Ta5+ gegen Sb5+ im Trirutiltyp. B behält die Struktur von Zn4Ta2O9 bei. Eine Position der oktaedrisch koordinierten M5+-Ionen ist mit Zn2+ statistisch besetzt. B ist metastabil.
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  • 48
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Pseudochalcogen Compounds. XVIII. Cyanamidolysis of Organophosphoryl-(phosphonyl-) chloridesCyanamidolytic reactions of organophosphoryl- and -phosphonyl chlorides are leading in dependence on the conditions of the reactions to metal-organo-cyanamidophosphates, M[(RO)2P(Y)NCN], and -cyanamidophosphonates, M[(RO)R'P(Y)NCN], M2[RP(Y)(NCN)2] respectively, as well as to the corresponding organo phosphoryl (phosphonyl) hydrogencyanamides, (RO)2P(Y)NHCN, (RO)R'P(Y)NHCN, RP(Y)(NHCN)2 and to Bis-(organophosphoryl)- and Bis-(organophosphonyl)-carbodiimides, (RO)2P(Y)-NCN-P(Y)(OR)2, (RO)R'P(Y)-NCN-P(Y)R' (OR). (Y: O, S). Conditions for synthesis as well as properties and structures of the new compounds are discussed on the basis of characteristic IR- and 31P-NMR-data.
    Notes: Cyanamidolysereaktionen an Organophosphoryl- und -phosphonyl-chloriden führen in Abhängigkeit von den gewählten Reaktionsbedingungen zu Metall-organo-cyanamidophosphaten, M[(RO)2P(Y)NCN], Metall-organo-cyanamidophosphonaten, M[(RO)R'P(Y)NCN], M2[RP(Y)(NCN)2] (Y: O, S), ferner zu den entsprechenden Organophosphoryl-(phosphonyl)-hydrogencyanamiden, (RO)2P(Y)NHCN, (RO)R'P(Y)NHCN, RP(Y)(NHCN)2 sowie zu Bis-(organophosphoryl)-carbodiimiden, (RO)2P(Y)—NCN—P(Y)(OR)2 und Bis-(organophosphonyl)-carbodiimiden, (RO)R'P(Y)-NCN-P(Y)R'(OR). Synthesebedingungen, Strukturen und Eigenschaften der neuen Verbindungen werden anhand der charakteristischen IR- und 31P-NMR-Daten diskutiert.
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  • 49
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    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 568 (1989), S. 73-84 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chemical transport of vanadiummonophosphide with iodineWell shaped crystals of vanadiummonophosphide can be grown by CVT using iodine as transport agent (e. g. → 900°C). As a result of thermodynamical calculations the evaporation and deposition of VP should be expressed by the following exothermic equilibrium \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm VP}_{\rm s} + 7{\rm /}2{\rm I}_{2,{\rm g}} {\rm = VI}_{4,{\rm g}} {\rm + PI}_{3,{\rm g}} . $$\end{document} At higher temperatures and low concentrations of Iodine, combined with desorption of moisture from the walls of the silica ampules endothermic deposition of VP according to \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm VP}_{\rm s} {\rm } + {\rm }2{\rm HI}_{\rm g} {\rm = VI}_{2,{\rm g}} {\rm + }1/2{\rm P}_{2,{\rm g}} {\rm } + {\rm H}_{2,{\rm g}} {\rm .} $$\end{document} has been observed. Assuming ΔBH°298(VPs) = -61 [kcal/mol] a satisfying agreement between thermodynamical calculations and experimental results can be reached.
    Notes: VP wandert bei hinreichender Zugabe von Iod im Temperaturgefälle (z. B. 800 → 900°C) in die heißere Zone. Bestimmend ist das exotherme Gleichgewicht:\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm VP}_{\rm s} + 7{\rm /}2{\rm I}_{2,{\rm g}} {\rm = VI}_{4,{\rm g}} {\rm + PI}_{3,{\rm g}} . $$\end{document} Bei niedrigen Transportmittelmengen und hohen Temperaturen (1125 → 1080°C) führt die Abgabe von H2O aus der Wand der Quarzglasampulle zu einer endothermen Transportreaktion: \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm VP}_{\rm s} {\rm } + {\rm }2{\rm HI}_{\rm g} {\rm = VI}_{2,{\rm g}} {\rm + }1/2{\rm P}_{2,{\rm g}} {\rm } + {\rm H}_{2,{\rm g}} {\rm .} $$\end{document} Thermodynamische Rechnungen zum chemischen Transport von VP stimmen mit den Experimenten unter der Annahme von ΔBH°298(VPs) = -61 [kcal/mol] befriedigend überein.
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  • 50
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    Zeitschrift für anorganische Chemie 568 (1989), S. 95-105 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chemical transport of the vanadium oxides V2O5, V3O7, and V6O13The suitability of water and some halogenating transport agents (NH4Cl, NH4Br, I2) for the chemical transport (temperature gradient 850/750 K) of V2O5, V3O7, and V6O13 has been investigated. Transport rates for V2O5 and V6O13 could be measured and reproduced. The best transport agent for V2O5 is NH4Cl or H2O. For V3O7 a combination of the transport agents I2/H2O give the best results and for V6O13 the combination of NH4Br/H2O was most appropriate.
    Notes: Die Eignung von Wasser und einigen halogenierenden Transportmitteln (NH4Cl, NH4Br, I2) zum chemischen Transport (Temperaturgefälle 850/750 K) von V2O5, V3O7 und V6O13 wurde untersucht. Für V2O5 und V6O13 konnten Transportraten reproduzierbar ermittelt werden. V2O5 ließ sich am besten durch einen Zusatz von NH4Cl oder von H2O transportieren. Für V3O7 ist die Transportmittelkombination I2/H2O und für V6O13 die Kombination NH4Br/H2O am besten geeignet.
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  • 51
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Chalcogenolates. 190. Esters of 2-Oxophenyldithioacetic Acid. 1. Preparation and CharacterizationThe dark red or yellowish brown colored title compounds C6H5—CO—CS—SR, where R = CH3, C2H5, C(CH3)3, CH2—C6H5, have been produced in one-pot synthesis by reaction of chloro acetophenone with sulfur in the presence of triethylamine followed by alkylation with the corresponding alkyl halide.The electron absorption, infrared, nuclear magnetic resonance, and mass spectra of the esters are given.
    Notes: Die dunkelrot bzw. gelbbraun gefärbten Titelverbindungen C6H5—CO—CS—SR mit R = CH3, C2H5, C(CH3)3 und CH2 — C6H5 wurden in Eintopfverfahren durch Umsetzung von Chloracetophenon mit Schwefel in Gegenwart von Triethylamin und anschließender Alkylierung mit dem entsprechenden Alkylhalogenid hergestellt.Die Elektronenabsorptions-, Infrarot-, Kernresonanz- und Massenspektren werden mitgeteilt.
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  • 52
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Thermal Behaviour of the Hydrogen Sulfates of Magnesium, Calcium, Strontium and BariumThe thermal behaviour of the solvent-free crystals of alkaline earth hydrogen sulfates has been investigated. The DTA and TG curves of MII(HSO4)2 indicate a decomposition following the equation Thermal treatment of Mg(HSO4)2 in static gas atmosphere yields α-MgSO4 which is transformed to α-MgSO4 at higher temperature. Contrary to that in dynamic gas atmosphere direct decomposition to α-MgSO4 can be observed. TpMg(HSO4)2 = 356°C, TpCa(HSO4)2 = 204°C, TpSr(HSO4)2 = 175°C, TpBa(HSO4)2 = 156°C. The strong difference between the peak temperatures of Mg(HSO4)2 and the other alkaline earth hydrogen sulfates may be explained not only through the higher covalency of the bondings in the Mg compound but, especially, through differences of their structures. Whereas the hydrogen sulfates of Ca, Sr, and Ba contain chains of edge-linked MIIO8 polyhedra, in Mg(HSO4)2 exist isolated MgO6 octahedra.
    Notes: Das thermische Verhalten der Kristalle der Erdalkalimetallhydrogensulfate wurde untersucht. Aus den DTA- und TG-Kurven folgt für die untersuchten Hydrogensulfate ein einstufiger Zerfall: Beim Aufheizen unter statischen Bedingungen wird aus Mg(HSO4)2 α-MgSO4 erhalten, das bei höherer Temperatur in α-MgSO4 übergeht, während unter dynamischen Bedingungen direkt α-MgSO4 erhalten wird. Die Zersetzungstemperaturen fallen mit zunehmendem Radius der Erdalkalimetallkationen: TpMg(HSO4)2 = 356°C, TpCa(HSO4)2 = 204°C, TpSr(HSO4)2 = 175°C, TpBa(HSO4)2 = 156°C. Der deutliche Unterschied in den Tp Werten zwischen Mg(HSO4)2 und den übrigen Erdalkalihydrogensulfaten ist neben dem stärker ausgeprägten Kovalenzbindungsanteil vor allem auf deren strukturelle Unterschiede zurückzuführen; Ba(HSO4)2, Sr(HSO4)2 und Ca(HSO4)2 bilden über gemeinsame Kanten verknüpfte MIIO8-Polyederketten, während in Mg(HSO4)2 isolierte MgO6-Oktaeder vorliegen.
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  • 53
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    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 569 (1989), S. 31-42 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A New Lithosilicate: Rb5LiNiSi2O8 = Rb5[LiNiSi2O8]Nearly colourless crystals of Rb5LiNiSi2O8 resulted by heating intimate mixtures of RbO0.6, LiO0.5, and SiO2 (Rb : Li : Si = 3 : 1.2 : 1) in tightly closed Ni-tubes. The crystal structure was determined (four-circle-diffractometer-data, 1 733 of 1 740 I0 (h kl), R = 6.9%, Rw = 5.5%, parameters see text). The new “Lithosilicate” crystallizes monoclinic (Space group C2/c) with a = 860.0(2), b = 1 026.2(2), c = 1 376.1(3) pm, β = 101.28(2)° (Guinier-Simon-powder-data), Z = 4. The structure is built up by chains ∞1[O2/2SiO2LiO2SiO2NiO2/22] where Si4+ resp. Li+ are coordinated tetrahedrally, Ni2+ however quadratic planar. The Madelung Part of Lattice Energy, MAPLE, and Effective Coordination Numbers, ECoN, these calculated via Mean Fictive Ionic Radii, MEFIR, are given.
    Notes: Fast farblose Kristalle von Rb5LiNiSi2O8 entstanden beim Tempern inniger Gemenge von RbO0.6, LiO0.5 und SiO2 (Rb : Li : Si = 3 : 1.2 : 1) in fest verschlossenen Ni-Bömbchen. Die Kristallstruktur wurde aufgeklärt (Vierkreisdiffraktometerdaten, 1 733 von 1 740 I0(h kl), R = 6,9%, Rw = 5,5%, Parameter siehe Text). Das neue “Lithosilicat” kristallisiert monoklin (Raumgruppe C2/c) mit a = 860,0(2), b = 1026,2(2), c = 1376,1(3) pm, β = 101,28(2)° (Guinier-Simon-Pulverdaten), Z = 4. Die Struktur wird aus Ketten ∞1[O2/2SiO2LiO2SiO2NiO2/2]2 aufgebaut, in denen Si4+ bzw. Li+ tetraedrisch, Ni2+ jedoch quadratisch planar koordiniert ist. Der Madelunganteil der Gitterenergie, MAPLE, sowie Effektive Koordinationszahlen, ECoN, diese über Mittlere Fiktive Ionenradien, MEFIR, berechnet, werden angegeben.
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  • 54
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 569 (1989), S. 16-30 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The First Binuclear Oxoferrate(II): „Cs2K4[O2FeOFeO2]“For the first time „Cs2K4[Fe2O5]“ was obtained by annealing intimate mixtures of Cs2O, K2O, and CsFeO2 (molar ratio Cs : K : CsFeO2 1.3 : 2.1 : 1) in a closed Fe-cylinder (74 d; 470°C) in the form of red single crystals. The structure determination (four-circle diffractometer, MoKα, 760 out of 857 Io(h kl); R = 5.8%, Rw = 4.6%) confirms the space group C2/m; a = 707.4, b = 1138.5, c = 699.7 pm, β = 91.76°, Z = 2. Essential part of the structure is the binuclear, planar [O(1)2Fe—O(2)—FeO(1)2]6- group which is for the first time observed with oxoferrates(II).Despite different space groups the crystal structure is related to that of Rb2Na4[Co2O5].
    Notes: „Cs2K4[Fe2O5]“ wurde erstmals durch Tempern inniger Gemenge von Cs2O, K2O und CsFeO2 (Einwaageverhältnis Cs:K:CsFeO2 1,3 : 2,1 : 1) in einem verschlossenen Fe-Zylinder (74 d; 470°C) in Form von granatroten Einkristallen erhalten. Die Strukturaufklärung (Vierkreisdiffraktometerdaten, MoKα, 760 von 857 Io(h kl); R = 5,8%, Rw = 4,6%) belegt die Raumgruppe C2/m; a = 707,4, b = 1138,5, c = 699,7 pm, β = 91,76°, Z = 2. Wesentlicher Teil der Kristallstruktur ist die zweikernige, planare Baugruppe [O(1)2Fe—O(2)—FeO(1)2]6-, die erstmals bei Oxoferraten(II) beobachtet wird.Die Struktur ist trotz unterschiedlicher Raumgruppen verwandt mit der von Rb2Na4[Co2O5].
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  • 55
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions to the Chemistry of Phosphorus. 191. On the Reaction Behavior of Sodium Tetraphosphinoborate NaB(PH2)4Sodium tetraphosphinoborate rearranges to sodium heptaphosphinodiborate, Na[(PH2)3B—PH2—B(PH2)3] (1), at moderate temperatures in the presence of tetrahydrofuran. By reacting NaB(PH2)4 with BH3 ß THF sodium tetrakis(boranephosphino)borate, NaB(PH2BH3)4 (2), is formed, which has a remarkable thermal stability, but is not stable without solvent. With methyl iodide, the easily decomposible triphosphinoborane-methylphosphane, B(PH2)3PH2CH3 (3), has been obtained. The 31P- and 11B-NMR data of 1-3 are reported and discussed.
    Notes: Natriumtetraphosphinoborat lagert sich in Gegenwart von Tetrahydrofuran schon bei mäßigen Temperaturen in Natrium-heptaphosphinodiborat, Na[(PH2)3B—PH2—B(PH2)3] (1), um. Bei der Reaktion von NaB(PH2)4 mit BH3 · THF entsteht Natriumtetrakis(boranphosphino)borat, NaB(PH2BH3)4 (2), das eine bemerkenswerte thermische Stabilität aufweist, lösungsmittelfrei aber nicht beständig ist. Mit Methyliodid wird das leicht zersetzliche Triphosphinoboranmethylphosphan, B(PH2)3PH2CH3 (3), gebildet. Die 31P- und 11B-NMR-Daten von 1-3 werden mitgeteilt und diskutiert.
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  • 56
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cyclic Diazastannylenes. XXVIII. Inorganic Polycyclic Compounds from the Reaction of Bis(amino)stannylene or Iminostannylene with SnCl2, SnBr2, and tert-Butoxitin(II) Chloride or BromideThe cyclic bis(amino)stannylene 1 may react with tert-butoxitin(II) chloride or bromide yielding a Lewis acid-base adduct 4 resp. 5, in which the two molecules are held together via N→Sn (233.8(3) pm) and O→Sn (215.1(2) pm) bonds. The resulting adduct 4 contains therefore two four membered rings sharing one common edge as found by X-ray structure determination. If 1 is allowed to react with SnCl2 or SnBr2, the salts Me2Si(NtBu)2Sn2Br+Sn2Br5- (7) are formed. Structure analysis reveals the cations in 6 and 7 to be very similar: SnCl+ and SnBr+ are coordinated by the “trihapto ligand” 1 in a way resulting a polycyclic SiN2Sn2X-arrangement. To a central Sn2N2 tetrahedron Si and halogen X are added occupying and bridging two opposite edges (mean values: N—Sn = 232(5) (6), N—Sn = 230(2) (7), Sn—C1 = 265(1), Sn- Br = 275(1) pm). The reaction intermediate (SnNtBu)2 adds to SnCl2 to form the crystalline polymer ( tBuN)2Sn3C12 (8). X-ray structure determination reveals the solid to be built up by one-dimensional chains of polycyclic Sn3(NtBu)2C13 sharing two chlorine atoms with neighbouring units. The unit Sn3(NtBu)2C13 can be visualized as an equilateral triangle of chlorine atoms, on which a smaller triangle of tin atoms is superimposed; the corners of the smaller triangle being located in the middle of the larger triangle's edges. The tin atoms are bipyramidally coordinated by two N- tBu-groups thus forming a nearly perfect Sn3N2s trigonal bipyramide (Sn—N = 222.7(3) pm). Two chlorine atoms of the triangle are connected to neighbouring units, the chlorine atoms thus attain an unusual nearly square-planar coordination sphere (Sn—Cl(mean) = 308(5) pm). The tertbutyl groups at the nitrogen atoms “screen” the inorganic part of the structure leading to a layer structure.
    Notes: Das cyclische Bis(amino)stannylen 1 reagiert mit tert-Butoxizinn(II)-chlorid oder -bromid zu einem Lewis-Säure-Base-Addukt 4 bzw. 5, in dem die beiden Moleküle über N→Sn- (233,8(3) pm) und O→Sn- (215,1(2) pm) Bindungen zusammengehalten werden, was zur Bildung zweier anellierter Vierringe führt (Röntgenstrukturanalyse von 4). Setzt man 1 hingegen mit SnCl2 oder SnBr2 um, so entstehen die “Salze” Me2Si(NtBu)2Sn2Br+Sn2Br5- (7). Gemäß Strukturanalysen sind die Kationen in 6 und 7 strukturell nahe verwandt: SnCl+ bzw. SnBr+ werden von dem “Trihaptoliganden” 1 so koordiniert, daß eine polycyclische SiN2Sn2X-Einheit mit einem N2Sn2-Tetraeder und kantenüberbrückenden Si und Halogen (X) entsteht (Mittelwerte : N—Sn = 232(2) (6), 230(2) (7), Sn—Cl = 265(1), Sn—Br = 275(1) pm). (tBuNSn)2, eine kurzlebige Zwischenstufe, addiert sich an SnCl2 unter Bildung eines kristallinen Polymers (tBuN)2Sn3Cl2 (8). Der Festkörper besteht nach Röntgenstrukturanalyse aus einer unendlichen Kette von (tBuN)2Sn3Cl3-Polycyclen, die sich mit benachbarten Einheiten jeweils zwei Chloratome teilen. (tBuN)2Sn3Cl3 bildet ein gleichseitiges Dreieck aus Chloratomen, auf dessen Kantenmitten ein zweites gleichseitigtes Dreieck aus Zinnatomen hineingestellt ist. Diese sind ihrerseits durch (NtBu)-Gruppen trigonal bipyramidal verknüpft. Die verbrückenden Chloratome besitzen eine ungewöhnliche planare, fast quadratische Koordination (Sn—Cl(Mittel) = 308(5) pm). Der mittlere Sn3N2-Polycyclus der Figur kann als nahezu perfekte trigonale Bipyramide beschrieben werden (Sn—N = 222,7(3) pm). Die tert-Butylgruppen an den Stickstoffatomen schirmen den anorganischen Teil der Struktur so ab, daß eine Schichtstruktur entsteht.
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  • 57
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Element-Element-Bonds. V. Synthesis, Molecular and Crystal Structure of Tetrakis-(Trimethylstannyl)distibaneLithium bis(trimethylsilyl)antimonide · 2 tetrahydrofuran reacts with benzyl chloride to form benzylbis(trimethylsilyl)stibane 1 which by treatment with chlorotrimethylstannane smoothly affords its trimethylstannyl derivative 2. Selective photochemical decomposition of 2 yields dark red tetrakis(trimethylstannyl)distibane 4; from benzene modification 4a is precipitated.Comparative X-ray structure determinations of 4a at +20 and -120°C as well as of homologous tetrakis(trimethylsilyl)distibane 3 at -120°C (+20°C: [2]) show the Sb…Sb contacts within the almost linear chains of Sb—Sb dumb-bells to be shortened at -120°C by 7 (4a) and 10 pm (3), respectively. On the contrary, the Sb—Sb bond is not lengthened accordingly as found for tetramethyldistibane previously [3, 4].Molecular parameters determined for 4a at +20°C {Sb—Sb 288; Sb—Sn 280 pm; Sb—Sb—Sn 91° and 96°; Sn—Sb—Sn 92°} are in agreement with corresponding values of a second modification 4b obtained by Dräger, Breunig and coworkers [5]. The crystal structures of 3 and 4b are isotypic (type B) and related to the homeotypic one of 4a (type A).
    Notes: Das aus Lithium-bis(trimethylsilyl)antimonid · 2 THF(1) THF: Tetrahydrofuran; DME: 1,2-Dimethoxyethan; TMS: Tetramethylsilan. und Benzylchlorid dargestellte Benzylbis(trimethylsilyl)stiban 1 setzt sich mit Chlortrimethylstannan zum Trimethylstannyl-Derivat 2 um. Dessen selektive Zersetzung am Tageslicht liefert das dunkelrote Tetrakis(trimethylstannyl)distiban 4.Vergleichende Röntgenstrukturanalysen bei +20 und -120°C zeigen sowohl für die aus Benzol kristallisierende Modifikation 4a als auch für das homologe Tetrakis(trimethylsilyl)distiban 3 (+20°C: [2]), daß die bei tiefer Temperatur innerhalb der fast linearen Ketten von Sb—Sb-Hanteln eintretende Verkürzung der Sb…Sb-Kontakte um 7 (4a) bzw. 10 pm (3) nicht wie beim Tetramethyldistiban [3, 4] zu einer Verlängerung der Sb—Sb-Bindung führt.Die von uns an 4a ermittelten Bindungsparameter {+20°C: Sb—Sb 288; Sb—Sn 280 pm; Sb—Sb—Sn 91°, 96° Sn—Sb—Sn 92°} stimmen gut mit den kürzlich von Dräger, Breunig u. Mitarb. [5] an einer zweiten Modifikation 4b erhaltenen Werten überein. Während die Kristallstrukturen von 3 und 4b isotyp sind (Typ B), ist die Kristallstruktur von 4a (Typ A) als hierzu homöotyp zu beschreiben.
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  • 58
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of N-Chloroacetoneimine with Molybdenum Pentachloride and Tungsten Hexachloride. Crystal Structure of Me2C=NH2[MoOCl4]WCl6 reacts with N-chloroacetoneimine under elimination of chlorine and formation of pentachloro-isopropylideneimino-tungsten(VI), Cl5W=N=CMe2, a brown-black crystal powder, which was characterized by i.r. spectroscopy. MoCl5 reacts in a similar way, although only a product mixture can be obtained. Partial hydrolysis of this mixture yields isopropylideneiminium-tetrachlorooxomolybdate(V), Me2C=NH2+[MoOCl4]-, of which the crystal structure was determined (2323 unique observed reflexions, R = 0.049). Space group P21/c, Z = 4, a = 878.6, b = 907.2, c = 1252.2 pm, β = 91.29°. The compound consists of Me2C=NH2+ ions with a planar arrangement of the skeletal atoms and a CN bond length of 126.7 pm and of dimeric, centrosymmetric anions [MoOCl4]22- having Mo atoms linked via asymmetric chloro bridges (MoCl distances 238.4 and 307.6 pm). The longer Mo—Cl contacts are located in the trans-positions of the terminal oxoligands (MoO distance 164 pm).
    Notes: WCl6 reagiert mit N-chloracetonimin unter Chlorabspaltung und Bildung von Pentachlor(isopropylidenimido)wolfram(VI), Cl5W=N=CMe2, einem schwarzbraunen Kristallpulver, das durch sein IR-Spektrum charakterisiert wird. ähnlich verläuft die Umsetzung mit MoCl5, wobei allerdings kein einheitliches Produkt isoliert werden kann. Durch partielle Hydrolyse entsteht aus diesen Produkten Isopropylideniminiumtetrachloro-oxomolybdat(V), Me2C=NH2+[MoOCl4], von dem wir eine Kristallstrukturanalyse angefertigt haben (2323 unabhängige beobachtete Reflexe, R = 4,9%). Raumgruppe P21/c, Z = 4, Gitterabmessungen: a = 878,6; b = 907,2; c = 1252,2 pm; β = 91,29°. Die Verbindung besteht aus Kationen Me2C=NH2+, deren Gerüstatome in einer Ebene liegen und die eine CN-Bindungslänge von 126,7 pm haben, sowie zentrosymmetrischen dimeren Anionen [MoOCl4]22-, deren Mo-Atome über asymmetrische Chlorobrücken mit Mo—Cl-Abständen von 238,4 pm und 307,6 pm verknüpft sind. Die langen Mo—Cl-Kontakte befinden sich in trans-Stellung zu den terminal gebundenen Oxoliganden (Abstand MoO = 164 pm).
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  • 59
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: [Cl3PNPCl3][MoNCl4], a Compound having Columns of Stacked AnionsThe title compound is formed by the reaction of [Cl3PNPCl3]Cl with MoNCl3 in CH2Cl2 and subsequent precipitation with CCl4 in from of orange-red crystals. According to the 31P-NMR spectrum, the compound exists as its isomer phosphaneiminate [Cl5Mo(NPCl2NPCl3)] in CD2Cl2/CH3CN solution. The crystal structure of [Cl3PNPCl3][MoNCl4] is isotypic with that of [Cl3PNPCl3][MoOCl4] and shows the same kind of two-dimensional disorder. X-ray diffraction patterns show planes of diffuse scattering as well as Bragg reflexions. The latter correspond to an averaged structure with a = 1590.0, b = 1141.6, c = 418.0 pm, space group Pba2, Z = 2. In the averaged structure (606 reflexions, R = 0.071) the atom sites have fractional occupation. The real structure consists of square-pyramidal [MoNCl4]- ions stacked to form columns with alternating MoN distances of 175 and 243 pm. The packing of the columns is disordered in that the [MoNCl4]- pyramids point either in the +c or -c direction. The [Cl3PNPCl3]+ ions are stacked in the c direction and show two types of disorder, namely a displacement parallel to c and a rotation by 120° about the P—P axis.
    Notes: Die Zielverbindung entsteht durch Umsetzung von [Cl3PNPCl3]Cl mit MoNCl3 in CH2Cl2 und anschließender Fällung mit CCl4 in Form orangeroter Kristalle. Nach dem 31P-NMR-Spektrum liegt die Verbindung in CD2Cl2/CH3CN-Lösung als strukturisomeres Phosphaniminat [Cl5Mo(NPCl2NPCl3)] vor. [Cl3PNPCl3][MoNCl4] kristallisiert isotyp zu [Cl3PNPCl3][MoOCl4] und zeigt die gleiche zweidimensionale Fehlordnung wie dieses. In den Röntgenbeugungsdiagrammen treten Ebenen von diffuser Streuung senkrecht zu c* neben Braggschen Reflexen auf. Aus den letzteren ergibt sich eine gemittelte Struktur einer Subzelle mit a = 1590,0, b = 1141,6, c = 418,0 pm, Raumgruppe Pba2, Z = 2. Aus der gemittelten Struktur (606 Reflexe, R = 7,1%) mit partiell besetzten Atomlagen läßt sich die tatsächliche Struktur und ihre Fehlordnung ableiten. Quadratische pyramidale [MoNCl4]--Ionen sind zu Strängen mit abwechselnden MoN-Abständen von 175 und 243 pm gestapelt. Die Stränge sind fehlgeordnet gepackt, indem die [MoNCl4]--Pyramiden entweder in die +c oder -c-Richtung weisen. Die [Cl3PNPCl3]+-Ionen sind zu Säulen parallel c gestapelt und auf zweierlei Art fehlgeordnet, nämlich durch Versetzung in Richtung c und durch Einnahme von dreierlei Positionen, die sich durch Drehung um 120° um die P—P-Verbindungslinie unterscheiden.
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  • 60
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of Ferrocenyltriethylstannanes and Electronic Properties of Substituted Ferrocenyl LigandsFerrocenyltriethylstannanes of the type RSnEt3 [R = Et3SnC5H4FeC5H4, C5H5FeC5H3(2-CH2NMe2), C5H5FeC5H3(2-CH2NC5H10), C5H5FeC5H3(2-CH2OMe), MeOCH2C5H4FeC5H4] were synthesized from Et3SnCl and the corresponding ferrocenyl lithium derivatives. The compounds were characterized by elementary analyses, 1H-, 13C-, 119Sn-n.m.r. and i.r. spectroscopic investigations. From the coupling constants 1J(119Sn—13CEt) the electronic influence of substituted ferrocenyl ligands was estimated.
    Notes: Ferrocenyltriethylstannane des Typs RSnEt3 [R = Et3SnC5H4FeC5H4, C5H5FeC5H3(2-CH2NMe2), C5H5FeC5H3(2-CH2NC5H10), C5H5FeC5H3(2-CH2OMe), MeOCH2C5H4FeC5H4] wurden aus Et3SnCl und den entsprechenden Ferrocenyllithium-Derivaten synthetisiert und mittels ihrer 1H-, 13C-, 119Sn-NMR- und IR-Spektren sowie elementaranalytisch charakterisiert. Aus den Kopplungskonstanten 1J(119Sn—13CEt) wurde der elektronische Einfluß der substituierten Ferrocenylreste abgeschätzt.
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  • 61
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 572 (1989), S. 7-17 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: NaNb10O18-a New Oxoniobate with [Nb6O12]-ClustersGolden reflecting single crystals and black powders of NaNb10O18 have been prepared by heating a mixture of NaNbO3, NbO, NbO2 and B2O3 (as mineralizer) at 900°C. The compound crystallizes in P21/c with a = 784.9(5), b = 931.6(4), c = 1028.1(3) pm, β = 110.53(4) und Z = 2 in a new structure type.The crystal structure is formed from common close packed sheets of O atoms, Na atoms and Nb6 octahedra. Characteristic building groups are NbO6 octahedra (Nb5+) and Nb6O12 clusters with short distances dNb—Nb = 277-288 pm. The number of valence electrons per Nb6O12 cluster is 15 or 14 assuming that one electron belongs to the four Nb5+ atoms. Extended Hückel calculations, metallic conductivity and Pauli type paramagnetism however would favour the model of one delocalized electron per formula unit according to (the formal description) Na+(Nb6)16+(Nb4)20+(O18)36-e-. The Madelung part of the lattice energie (MAPLE) has been calculated and discussed.
    Notes: NaNb10O18 wurde in Form goldgelber Einkristalle und schwarzer Pulver durch Tempern eines Gemenges aus NaNbO3, NbO und NbO2 sowie B2O3 (als Mineralisator) bei 900°C dargestellt. Die Verbindung kristallisiert in P21/c mit a = 784,9(5), b = 931,6(4), c = 1 028,1(3) pm, β = 110,53(4)° und Z = 2 in einem neuen Strukturtyp.Die Kristallstruktur besteht aus gemeinsam dicht gepackten Schichten von O-Atomen, Na-Atomen und Nb6-Oktaedern. Neben NbO6-Oktaedern (Nb5+) liegen charakteristische Nb6O12-Cluster mit kurzen Abständen dNb—Nb = 277-288 pm vor. Die Zahl der Valenzelektronen pro Nb6O12-Cluster beträgt 15 oder 14, wenn man ein Elektron den vier Nb5+-Atomen in den NbO6-Oktaedern zuordnet. Extended-Hückel-Rechnungen, metallische Leitfähigkeit und Pauli-Paramagnetismus weisen aber eher auf ein delokalisiertes Elektron pro Formeleinheit gemäß (der sehr formalen Schreibweise) Na+(Nb6)16+(Nb4)20+(O18)36-e- hin. Der Madelunganteil der Gitterenergie (MAPLE) wurde ebenfalls berechnet und diskutiert.
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  • 62
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Crystal Structure of the μ-Dinitridosulfate(II) Complex [Na-15-crown-5]2[μ-(NSN)(MoF5)2]The title compound is formed at room temperature by the reaction of [MoCl4(NSCl)]2 with the equivalent amount NaF in acetonitrile in presence of the crown ether 15-crown-5. It forms black, moisture-sensitive crystals that were characterized by an X-ray structure determination (1 756 unique observed reflexions, R = 0.073). Crystal data (19°C): a = 965.5, b = 3 219, c = 1 161.1 pm, β = 95.42°; space group P21/n, Z = 4. The structure consists of ion triples in which the [Na-15-crown-5]+ ions are associated with the [μ-(NSN)(MoF5)2]2- ions via Na…F contacts of 215 to 265 pm length. Each of the two MoF5 units of the anion is linked with one of the N atoms of the dinitridosulfate(II) group; bond angle NSN 103°, MoN bond lengths 172 pm.
    Notes: Die Titelverbindung entsteht durch Reaktion von [MoCl4(NSCl)]2 mit der äquivalenten Menge NaF in Acetonitril bei Raumtemperatur in Anwesenheit des Kronenethers 15-Krone-5. [Na-15-Krone-5]2[μ-(NSN)(MoF5)2] bildet in der Aufsicht schwarze, feuchtigkeitsempfindliche Kristalle, die wir durch eine röntgenographische Strukturanalyse charakterisiert haben. Raumgruppe P21/n, Z = 4, Gitterabmessungen (19°C): a = 965,5; b = 3 219; c = 1 161,1 pm; β = 95,42° (1 756 unabhängige, beobachtete Reflexe, R = 7,3%). Die Verbindung bildet Ionentripel, die durch Na…F-Kontakte von 215 bis 265 pm der Na-Atome der Kationen [Na-15-Krone-5]+ mit einem bzw. zwei F-Atomen der Anionen [μ-(NSN)(MoF5)2]2- zustandekommen. Die beiden MoF5-Einheiten des Anions sind über die N-Atome der Dinitridosulfat(II)-Gruppe (Bindungswinkel NSN = 103°) mit MoN-Abständen von 172 pm verknüpft.
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  • 63
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Crystal Structure of the Nitrido Complex [Na-15-crown-5]2[MoNF4]2 · 2 CH3CNThe title compound is synthesized by the reaction of [MoCl4(NSCl)]2 with excess NaF in boiling acetonitrile in the presence of the crown ether 15-crown-5. [Na-15-crown-5]2[MoNF4]2 · 2 CH3CN forms yellow crystals, which were characterized by an X-ray structure determination. Space group P1, Z = 1. Lattice dimensions at -90°C: a = 855.5, b = 1 069.9, C = 1 143.5 pm, α = 105.71°, β = 95.29°, γ = 102.25° (4 096 independent observed reflexions, R = 0.039). Short Na…F contacts of 234 pm with the four axial fluoro ligands of the dimeric anion [MoNF4]22- allow formulation of a triple ion. The centrosymmetric anion is dimerized by bent fluoro bridges with Mo—F distances of 198 and 245 pm. The long Mo—F distances of the MoF2Mo ring are in transposition to the nitrido ligands, the bond lengths of which (165 pm) correspond to triple bonds.
    Notes: Die Titelverbindung entsteht durch Reaktion von [MoCl4(NSCl)]2 mit überschüssigem NaF in siedendem Acetonitril in Gegenwart des Kronenethers 15-Krone-5. [Na-15-Krone-5]2[MoNF4]2 · 2 CH3CN bildet gelbe Kristalle, die wir durch eine röntgenographische Strukturanalyse charakterisiert haben. Raumgruppe P1, Z = 1. Gitterabmessungen (-90°C): a = 855,5; b = 1 069,9; c = 1 143,5 pm; α = 105,71°, β = 95,29°; γ = 102,25° (4 096 unabhängige, beobachtete Reflexe, R = 3,9%). Die Verbindung bildet Ionentripel, die durch je zwei kurze Na…F-Kontakte von 234 pm mit den vier axial angeordneten Fluorliganden des dimeren Anions [MoNF4]22- zustandekommen. Die Dimerisierung zum zentrosymmetrischen Anion erfolgt über gewinkelte Fluorobrücken mit Mo—F-Abständen von 198 und 245 pm. Die langen Mo—F-Abstände des MoF2Mo-Ringes befinden sich in trans-Position zu den Nitridoliganden, deren MoN-Abstände von 165 pm Dreifachbindungen entsprechen.
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    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zur Chemie der Silicium-Stickstoff-Verbindungen. 165. Über die kristallinen Produkte der Reaktion von Siliciumtetrachlorid mit Stickstoff in einer Glimmentladung. Einkristall-Röntgenstruktur-Analyse von N(SiCl3)3 und Cl3SiN(SiCl2)2NSiCl3Von den beiden kristallinen Produkten aus den Reaktionen von Silicium-tetrachlorid/Stickstoff-Gemischen in Glimmentladungen konnte das leichter flüchtige (Schmp. 78°C) als Tris(trichlorsilyl)amin NSi3Cl9 bestätigt, das schwerer flüchtige (Schmp. 66°C) als N,N′-Bis-(trichlorsilyl)-Si,Si′-tetrachlorcyclodisildiazan N2Si4Cl10 erkannt werden. Der Beweis erfolgte massen- und schwingungsspektroskopisch wie röntgenstrukturanalytisch. NSi3Cl9 besitzt eine praktisch ebene NSi3-Anordnung mit N—Si-Abständen 1,734(2) Å. In N2Si4Cl10 ist der N2Si4-Molekülteil ebenfalls nahezu planar angeordnet, mit endocyclischen Bindungswinkeln N—Si—N 89,2(1)° und Si—N—Si 90,8(1)° sowie mittleren N—Si-Abständen von 1,731(3) im Ring und von 1,687(3) Å exocyclisch.
    Notes: Of the two crystalline products obtained by reacting a silicon tetrachloride/nitrogen mixture in a glow discharge tube, the more volatile (m. p. 78°C) has been confirmed to be tris(trichlorosilyl)amine NSi3Cl9 whereas the less volatile component (m. p. 66°C) has been identified as N,N′-bis(trichlorosilyl)-Si,Si′-tetrachloro-cyclodisildiazane N2Si4Cl10. These conclusions are supported by mass and vibrational spectroscopy and single crystal X-ray structures. NSi3Cl9 possesses a nearly planar NSi3 skeleton with average N—Si distances of 1.734(2) Å. The N2Si4 fragment of N2Si4Cl10 is roughly planar with endocyclic N—Si—N and Si—N—Si angles of 89.2(1) and 90.8(1)°, respectively, and mean N—Si distances of 1.731(3) (endocyclic) and 1.687(3) Å (exocyclic).
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