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1,3-Beta-D-glucan derived from baker's yeast was chemically modified in two steps yielding crosslinked carboxymethyl glucan as the sodium salt (2). After cation exchange with hexadecyltrimethylammonium chloride, a hydrophobic adsorbent (3) was obtained which showed an excellent binding of the estrogenic mycotoxin zearalenone with a maximum adsorption of up to 183 mg/g. Compound 3 additionally showed a relatively high adsorption capacity for the trichothecene T-2 toxin of at least 10 mg/g. Starting from 2, various derivatives were prepared by cation exchange using quaternary ammonium salts bearing substituents besides methyl from four to 18 carbon atoms. The adsorption of T-2 toxin on these derivatives were compared with compound 3 leading to the conclusion that 3 is the best adsorbent of all investigated tetraalkylammonium-modified derivatives of 2.

A new control strategy for the methanogenic reactor of a two-phase anaerobic digestion system has been developed and successfully tested on the laboratory scale. The control strategy serves the purpose to detect inhibitory effects and to achieve good conversion. The concept is based on the idea that volatile fatty acids (VFA) can be measured in the influent of the methanogenic reactor by means of titration. Thus, information on the output (methane production) and input of the methanogenic reactor is available, and a (carbon) mass balance can be obtained. The control algorithm comprises a proportional/integral structure with the ratio of (a) the methane production rate measured online and (b) a maximum methane production rate expected (derived from the stoichiometry) as a control variable. The manipulated variable is the volumetric feed rate. Results are shown for an experiment with VFA (feed) concentration ramps and for experiments with sodium chloride as inhibitor.

Reducing agents required in the dyeing process for vat and sulfur dyes cannot be recycled and lead to problematic waste products. The electrochemical reduction of indigo on a fixed bed cathode consisting of graphite granules has been investigated by spectrophotometric experiments in laboratory cells. Experiments yield information about the kinetics and show the possibility of this process for production of water soluble leuco indigo, which offers environmental benefits. The influence of noble metals deposited on the granules and of different pretreatment methods of the graphite is demonstrated. In addition, the immobilization of quinoid molecules on the graphite surface has been investigated.

Increasing eco-efficiency of textile wet processes has become an important topic. Reducing agents required for the application of vat dyes (i.e. indigo) cannot be recycled, and lead to problematic waste products. Therefore, modern economical and ecological requirements are not fullfilled. The application of electrocatalytic hydrogenation of vat dyes at electrodes comprising a thin grid coated with a layer of nickel in which fine particles of Raney nickel are dispersed has been investigated by spectrophotometric and voltammetric experiments in laboratory cells. Experiments show the feasibility of this new route which offers tremendous environmental benefits and has a vast potential in textile dyeing processes, because it does not require any reducing agent.

The paper contains an extended summary of an invited plenary talk given at the Workshop on Active Chaos at the Los Alamos National Laboratory on 29-31 May 2001 by one of us (F.S.R.). (c) 2002 American Institute of Physics.

Reducing agents required in the dyeing process for vat and sulfur dyes cannot be recycled, and lead to problematic waste products. Therefore, modern economical and ecological requirements are not fulfilled. The industrial feasibility of the direct electrochemical reduction of indigo as a novel method has been determined and a preliminary optimization of electrolytic conditions was performed using a laboratory-scale flow-cell system. The role of current density, pH, temperature and the rate of mass transport are discussed. The influence of particle size reduction by the application of ultrasound is critically considered.

Zahlreiche chemische Reaktionen laufen so schnell ab, dass ein signifikanter Umsatz bereits auftritt, bevor Konzentrationsinhomogenitaten bis in den molekularen Bereich ausgeglichen werden konnen. Die Transformation findet dabei in Regionen statt, in denen lokal vollig andere Konzentrationen vorliegen, als makroskopisch angenommen wird. Infolge der beschrankten Mischrate der Edukte im Reaktor treten daher Anderungen in der Reaktionsgeschwindigkeit auf, die signifikanten Einfluss auf die Produkteverteilung haben konnen. Kenntnisse daruber ermoglichen eine optimale Nutzung von Rohstoffen durch gezieltere Konstruktion und Operation von Reaktoren (Selektivitatsmaximierung). Mischungsmaskierte Reaktionen haben aber auch das Potential, quasi als Mikroproben, Inhomogenitaten bis in den molekularen Bereich zu registrieren. Sie fordern damit das Verstandnis uber Mischprozesse und manchmal auch uber den Verlauf von organisch-chemischen Reaktionen, deren Mechanismen nicht im Einklang mit allgemeinen mechanistischen Prinzipien der Chemie zu stehen scheinen. Many chemical reactions are so fast relative to mixing that significant conversion takes place before homogenization down to the molecular scale is reached. In such cases, the bond-breaking and bond-forming events mainly occur in regions where concentrations gradients are still present. Consequently the rate of mixing can have a pronounced effect on the kinetics and the product distribution in competitive chemical reactions. This review gives an account of such mixing-sensitive single-phase liquid-liquid chemical reactions where all reactants and products are soluble, because a better understanding of the coupling between mixing and chemical reaction is needed to optimize the product distribution by choosing the appropriate reactor geometry and mixing conditions. Additionally these reactions have the potential to be employed as an exploratory microprobe to investigate the local flow characteristics or the mixing process at the molecular level and to evaluate the mechanism of chemical reactions.

The major task in the recycling of Hexal used in air defense ammunition is the secure, environmentally friendly and cost-saving removal of the Hexal from the case. For this purpose a production plant was constructed, by which the Hexal can be extracted in one minute from four 35 mm grenades by means of drilling and application of high pressure water. The water treatment turned out to be the key step of this process. Increasingly severe environmental regulations force the industry to clean and reuse the water in the process. The diversity of the cleaning methods available is strongly limited by the explosive as material to be separated, by the broad particle size distribution, the high water throughput and the high purity request of the high-pressure pump. The implemented separation process consists of a sedimentation and a filter part. This offers the advantage that there are no moving parts in the system and therefore the maintenance is relatively simple.

The anaerobic biodegradation mechanisms of linear alcohol ethoxylates (LAE) were studied in incubation experiments with anoxic sewage sludge. Sophisticated analytical techniques were applied, such ...

The study on the range of applications of a cheap iron oxide/hydroxide modification as a H-transfer catalyst opened up a promising new route for the selective reduction of nitro groups in aromatic azo compounds. A series of monosubstituted 3- and 4-nitrophenylazobenzenes were reduced selectively by hydrazine hydrate in the presence of the iron oxide/hydroxide catalyst. The selectivity for the nitro group reduction vis-a-vis that of the azo bridge in substituted nitrophenylazobenzenes is higher for compounds with the nitro group in para position to the azo bridge than for the corresponding meta counterparts. This selectivity was enhanced with stronger electron-attracting properties of the substituent. Moreover, the selectivity for the reduction of the nitro group vis-a-vis that of the azo function can be enhanced by increasing the reaction temperature as the Arrhenius activation energy for the nitro reduction is about twice that for the azo cleavage.

The two typical, that is unstabilized and unconstrained, oxaphosphetane diastereomers (3RS,4SR)- (3) and (3RS,4RS)-4-cyclohexyl-2-ethyl-3,4-dimethyl-2,2-diphenyl-1,2λ5-oxaphosphetane (5) have been ...

A great variety of monosubstituted nitrobenzene derivatives has been reduced in good yield to the corresponding anilines with hydrazine hydrate in the presence of an iron oxide hydroxide catalyst prepared by precipitation from an aqueous iron(III) solution with sodium hydroxide. The dependence of the rate of reduction on the nature and the position of additional substituents other than the nitro group was determined by measuring the reaction kinetics. The rate is enhanced by electron- attracting substituents and decreased by electron- donating groups, which results in a positive slope of ρ =0.546 for the Hammett plot. Competitive reduction experiments with mixtures of two differently substituted nitrobenzene derivatives revealed that the nitro compound with the more electron- attracting substituent is reduced first.

The 27Al, 15N, 13C and 1H NMR spectra in DMSO and 27Al and 15N magic angle spinning NMR spectra of 2:1 aluminium(III) complexes derived from 5-chloro-2-hydroxyaniline azo coupling products with acetoacetanilide, 3-methyl-1-phenylpyrazol-5-one and 2-naphthol were measured and analysed. It was found that the aluminium atom is six-coordinated, being bound to two oxygens and the nitrogen originating from 2-hydroxy-5-chloroaniline of each ligand, in an analogous fashion to 2:1 cobalt(III) complexes described earlier. © 1998 John Wiley & Sons, Ltd.

The cyclopalladation of 1,1′-azonaphthalene (= di(naphthalen-1-yl)diazene; 2) with bis(hexafluoroacetyl-acetonato)palladium(II) (3; [Pd(hfa)2]) yields the ortho-palladated complex (1,1,1,5,5,5-hexafluoropentane-2,4-dionato-κ2O,O′)[1-(naphthalen-1-ylazo-κN2)naphthalen-2-yl-κC2]palladium(II) (4) as well as the peri-palladated complex (1,1,1,5,5,5-hexafluoropentane-2,4-dionato-κ2O,O′)[8-(naphthalen-1-ylazo-κN2)naphthalen-1-yl-κC1]-palladium(II) (5); their structures were corroborated by X-ray analyses. The formation of the novel peri-metallated product 5 containing a six-membered palladacycle strongly depends upon the reaction conditions.

Laser-Induced Fluorescence is used to tomographically produce volume information of concentration distribution in a turbulent shear flow. Based on Adaptive Least Squares Correlation (ALSC) of grey level distributions in small patches cut out of consecutive tomographically constructed observation volumes, 3-D fields of velocity, vorticity and rate-of-strain are determined with high spatial resolution, satisfactory temporal resolution and high accuracy. This novel technique opens new perspectives for the study of mixing processes.

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Silicon foils, prepared by electrocatalysis, consist of microcrystalline, porous silicon. The size of the crystallites ranges between 15 and 20 nm, whereas the average pore size is about 60 nm. The density of this material is 65% of that of crystalline silicon. It is p-type and could be made n-type by neutron activation. Electrical and optical measurements indicate that the charge carrier mobility is limited by the grain boundaries. The grain boundaries give, in addition, rise to strong recombination of charge carriers. The luminescence of the material was investigated in a few experiments, and attempts were made to fabricate solar cells from electrocatalytically produced silicon foils with the pn-junctions prepared by neutron activation. The luminescence showed a peak at about 570 nm. The open circuit voltages obtained with solar cells were in the range between 120 and 200 mV. Further experiments to increase the intensity of the luminescence and to improve the quality of the cells could not be made within the framework of this project. It is, however, expected that further experimentation leads to a better understanding of the properties of the material and to applications.

To evaluate the experimental conditions for the light-induced change of the molecular charge, the dependence of the photochromic reaction behaviour of the indolino spiro naphthoxazine compound 1,3,3-trimethyl-spiro[2H-indol 2,3′-[3H]naphth[2,1-b]-[1,4]oxazine] on the pH value of the solution is investigated. In the absence of UV light an acid–base equilibrium between the spiro form and a protonated closed form is established. By irradiation under appropriate acidic conditions the spiro form can be transformed into an open cationic form through the merocyanine form. Between the two open forms an acid–base equilibrium is established. Except for the closed protonated form the structures are confirmed by mean of NMR. The kinetics of the thermal ring-closing reaction of both forms are investigated by flash photolysis. It is shown that the ring-closing reaction proceeds exclusively via the merocyanine form. The pK values determined for both equilibria give the pH range, in which the light-induced change of the molecular charge occurs.

The cyclopalladation of two different types of aniline derivatives is described: the acetylated anilines N-(3-methylphenyl)acetamide (2a), 3-(acetylamino)-4-chlorobenzoic acid (2c), and N-(2-chlorophenyl)acetamide (2d) are cyclometalated easily with palladium(II) acetate and trifluoroacetic acid to yield the corresponding complexes 4a, 4c, and 4d, respectively, whereas the acetylated meta-toluidine N-(2-chloro-5-methylphenyl)acetamide (2b) cannot be metalated at the only accessible site between the acetylamino and the methyl group. This aromatic CH bond can be activated, however, with the second type of meta-toluidine derivatives: the 2-chloro-5, N-dimethyl-N-nitrosoaniline (3b) readily undergoes cyclopalladation to yield the corresponding PdII complex di-μ-trifluoro-acetato-bis[3-chloro-6-methyl-2-(N-methyl-N- nitrosoamino)phenyl-C,NO]dipalladium(II) (5b) containing a five-membered palladacycle with coordination of PdII at the nitroso N-atom, which is established by 15N-NMR spectroscopy.

A new diffusion cell is described which allows the permeability of membranes to be investigated. It is known that the diffusion behavior of a penetrant is influenced by the diffusional boundary layers existing on both sides of the membrane. A method is presented which enables the thicknesses of these diffusional boundary layers at the membrane to be determined by independently measurable hydrodynamic parameters

Increasing ecoefficiency of textile wet processes has become an important topic in our research group. Reducing agents required for the application of vat and sulfur dyes cannot be recycled, and they lead to problematic waste products. Therefore, modern aspects of economical and ecological requirements are not fulfilled. The application of direct electrochemical reduction of indigo as a novel route has been investigated by spectrophotometric and voltammetric experiments in laboratory cells. Experiments yield information about the reaction mechanism and the kinetics, and they show the possibility of this new route for production of water- soluble indigo, which offers tremendous environmental benefits.

Summary This work deals with the selective reduction of aromatic nitro compounds to the corresponding aromatic amines with hydrazine hydrate in the presence of catalytic amounts of a modified iron oxide hydroxide compound. The dependence of the rate of reduction on the nature and the position of additional substituents other than the nitro group was determined. The rate is enhanced by electron-withdrawing substituents and decreased by electron-donating groups. Moreover, our study on the range of application of this cheap iron oxide hydroxide modification as a H-transfer catalyst opened up a promising new route for the selective reduction of nitro groups in aromatic azo compounds. A series of monosubstituted 4-nitroazobenzenes were selectively reduced by hydrazine hydrate in the presence of the iron oxide hydroxide catalyst. The selectivity for the reduction of the nitro group vis-a-vis that of the azo bridge was increased with stronger electron-withdrawing properties of the substituent R. For 4-nitroazobenzenes with electron-donating substituents the rate constants of the reductive cleavage of the azo bridge and of the nitro group reduction are of the same order of magnitude. For the reduction of the nitro group (1) in the unsubstituted 4-nitroazobenzene and for the reductive cleavage of the azo function (3) in the corresponding 4-aminoazobenzene (Scheme 1), the Arrhenius activation energies were determined to be Ea(1)=81.5 kJ/mole and Ea(3)=46.6 kJ/mole, respectively. Thus, the selectivity for the reduction of the nitro group vis-a-vis that of the azo function can be enhanced by higher reaction temperatures.

The videogrammetric Least Square Matching Technique (LSM) presented by A. Grun in Chapter three of this volume can be applied to tomographically obtained threedimensional LIF images as shown by H.-G. Maas in this chapter. The method yields three shift components of a small cuboid and the nine components of the tensor describing its transformation, which is assumed to be affine. Provided a good estimate of it can be made for starting the iteration, no restriction is imposed on the magnitude of the shift by videogrammetry.

The accurate tracking of patterns in finite elements of a volume sequentially imaged in time by using Laser Induced Fluorescence (LIF) tomography requires high quality images of the dye distribution. Special attention must therefore be paid to the selection of the dye, the illumination system and the recording camera, keeping in mind the requirements imposed by the tracking procedure and the scales one wishes to resolve in a specific experiment.

It was possible to selectively introduce sulfate and carboxyl groups into defined positions of β-cyclodextrin. In addition, the distance between the sulfate groups could be increased with the aid of alkyl spacers in order to lower the negative charge density on the cyclodextrin. Investigations of the biological activity of these derivatives yield more information about the angiogenesis-inhibition mechanism. Thus, the modified cyclo-dextrins were tested for biological activity on the chick chorioallantoic membrane (CAM).

Laser induced fluorescence (LIF) is used to construct images of passive scalar concentration fields in turbulent flows. This technique was applied by Koochesfahani & Dimotakis (1986) and Dahm & Dimotakis (1990). We developed this technique into a flow tomography to observe three-dimensional turbulent fields of order of the Taylor microscale with a resolution sixteen times smaller than the Kolmogorov length scale.

The oscillatory peroxidase-oxidase reaction has been investigated by using NADH deuterated in the nicotinamide 4-A position. A considerable kinetic hydrogen/deuterium isotope effect on the oscillatory behavior was revealed, which may provide an additional valuable tool for mechanistic studies and for discriminating between various mechanistic models of the peroxidase-oxidase reaction. Particularly, this effect manifests in different oscillation frequencies. A sequence of simple and aperiodic oscillations was found between two stable steady states.

A problem of asymmetric swirling flow in a pipe has been analyzed by the finite volume numerical simulation of the three-dimensional incompressible Navier-Stokes equations expressed in cylindrical polar coordinates. The swirl is generated by one tangential inlet near the closed base of the duct. Because of the high value of the swirl number, S, a vortex breakdown forms near the base of the cylinder; it is of bubble-like shape. Downstream of the bubble the axial flow is at first wavy and finally tends toward the Poiseuille profile, while the swirl decays exponentially. At high enough axial Reynolds number, Re, the flow becomes time dependent.

The industrial feasibility of the electrocatalytic hydrogenation of indigo on Raney nickel electrodes as a suspension in an aqueous medium has been studied in a divided flow cell. The attempt was made to establish optimized conditions in the system, and a scale-up in indigo concentration to 10 g/L was achieved. Increasing pH can enhance the reduction rate and a maximum conversion has been found by optimizing current density and temperature. The reaction rate is clearly enhanced in the presence of ultrasonic waves and organic solvents. Methanol is among the best cosolvents and was used in concentrations of 10 vol %.With Raney nickel electrodes an optimized current efficiency of 13% could he reached at 95% conversion. This value was enhanced to 19% by using electrodes doped with platinum particles.

The magnetic and electrical properties of new copper arylcarboxylates are presented. Special emphasis on copper(II) terephthalate trihydrate (CuTT) is given, and the magnetic and electrical properties are correlated with the crystal structure, recently determined by us. We have obtained new conductor materials by partial reduction of CuTT. The properties of these new compounds are discussed.

The syntheses of 1-phenylazonaphthalene (1a) and its [3′-methyl- (1b), 4′-methoxy- (1c), 3′-methoxy- (1d)] derivatives are described. Cyclopalladation of these azo ligands with Pd(II) acetate or Na2PdCl4 leads to complexes with Pd(II) coordinated on the azo Nβ-atom and a PdC σ-bond at C(2) in the naphthalene moiety. The preference of Pd(II) for this type of metalation at C(2) over the palladation at the ortho positions of the phenyl ring or at the peri position of the naphthyl ring is believed to be largely due to steric effects and the different reactivities of the two arene moieties. Substitution of the acetato-bridge with bromide or iodide allows the syntheses of the corresponding bromo- and iodo-bridged complexes, and a chloro-bridged dimer complex can be converted to a monomeric ethylenediamino-Pd(II)-azo species with ethylenediamine. Cyclopalladation of sulfonated azo ligands leads to water-soluble Pd(II) complexes with a Pd-C σ-bond at C(2).

A simple mixing-reaction model has been developed [1] which allows a description and simulation of the coupling of the mass diffusion with the chemical reaction during the mixing process of two miscible reactant solutions. For competitive, consecutive as well as for competitive, parallel second-order reactions the general behaviour and the dependence of the product distribution on diffusion effects are calculated for semi-continuous reaction conditions using various simplifying assumptions. The usefulness of these assumptions is discussed with reference to the calculated predictions of two versions of the mixing-reaction model.

The influence of mass diffusion on substrate and positional selectivities is discussed. A simple model is developed which allows a description and simulation of the coupling of the mass diffusion with the chemical reaction during the mixing process of two reactant solutions. For competitive, consecutive reactions and competitive, parallel reactions the general behaviour and the dependence of the product selectivity on diffusion effects is demonstrated.

Die neu entwickelte Methode der Aciditatsbestimmung Feststoff-gebundener Sauren basiert aus der Sorption von Indikatoren und erlaubt die Ermittlung von H0 aus den Sorptionsisothermen.

A variety of cyclopalladated 1-arylazonaphthalenes is described, where ortho-palladation occurs at C(2) in the naphthyl ring or at C(2′ or 6′) in the phenyl moiety. Two examples of Peri-cyclopalladation at C(8) in the naphthyl ring are presented. The electronic and steric-influences of substituents at either arene moiety on the relative basicities of the azo-N-atoms and the relative nucleophilicities of the potential palladation sites C(2), C(2′ or 6′), and C(8) are discussed qualitatively in order to rationalize the observed regioselectivity.

The first acidity constants (pK1) and the zinc complex formation constants (pKzn) of 9 dyes of the type 1-(2-hydroxy-4′-X-5′-Y-phenylazo)-2-naphthol 1 were measured potentiometrically. The sorption behaviour of these dyes on zinc oxide in toluene demonstrates that first a Langmuir-type pseudo-equilibrium of the dye with a monomolecular edge-on adsorption (11) can be observed. The more acidic the dyes, the more is this equilibrium disguised by a faster dissolution of zinc ions from the surface to form (practically irreversibly) the polymeric 1:1 zinc-dye complex 10. This complex is detectable in electron micrographs. The discharge kinetics of dye-sensitized zinc oxide-binder layers in the dark and under irradiation by visible light (10 interference filters) was determined. Substituents X and Y have no detectable influence on the intrinsic discharge kinetics; however, they influence the formation of the polymer complex 10 which is contrast to 11 is not a good sensitizer.

The reaction of a cyclopalladated 1-arylazonaphthalene with tetrabutylammonium cyanide leads to an ortho-cyano-1-arylazonaphthalene and a 3-amino-aryl-benzo[g]indazole, depending upon whether triphenylphosphine or 1,2-bis(diphenyl-phosphino)ethane (DIPHOS) is used to monomerize the binuclear Pd(II)-complex. In a similar insertion reaction with cyclohexyl isocyanide the corresponding 3-(N-cyclohexyl)-aminoindazole is formed. A Pd(II)-isocyano complex is shown to be a possible intermediate in that conversion.

The results of this study show that three parameters are sufficient to describe the selectivity behaviour of nitrations influenced by mixing as long as a fast combination of the reactant solutions takes place and fast agitation is employed. This is in full agreement with the prediction of the mixing-reaction model developed previously [1]. Furthermore, the results show clearly that in nitromethane the formation rate of nitronium ions from nitric acid is slower than the mixing rate and the rate of the electrophilic substitution proper. From the mixing-disguised selectivity curves for the nitrations of durene and prehnitene with nitronium hexafluorophosphate in nitromethane the ratio of the rate constants k2 for the second nitrations can be estimated to be 1:2. For the two aromatic compounds the k1/k2 ratios are ≥ 104. Finally it could also be shown that small impurities in the solvent (e.g. water) can influence strongly the selectivity curves, depending on the method used for mixing.

In mixing-disguised azo coupling reactions the protons which are released during the electrophilic substitution steps cause a pH-gradient in the reaction zone. Since, owing to the acid-base pre-equilibria, these pH-gradients also determine the local concentrations of the reactants in the reaction zone, they also have an influence on the measured product distribution of such fast reactions. In the present work, the product distribution of the azo coupling of 1-naphthol with 4-sulfophenyldiazonium ion was experimentally measured and the results were compared with the distributions predicted from our mixing-reaction model developed previously [1]. Furthermore, some experimental evidence for the existence of isoselectivity points are presented, at which a change of the initial pH-value has no influence on the product distribution.

Thickness of diffusional boundary layer (δD) on a cellulose membrane was estimated by means of multiple membrane layer method using non-ionic diffusants. The values of δD estimated under a good stirring were 0.9-2 and 0.4-0.6×10-3cm at 80 and 30°C, respectively.Rates of dyeing (or desorption) of non-ionic dyes on nylon 6 and polyester yarn were determined carefully. Comparison of rate of dyeing curves determined with those calculated by Hill's equation revealed the presence of a sorption delay in the dyeing. The delay decreased significantly as the rate of stirring of dyebath was increased. The delay was attributed to the resistance to transport of dye across the diffusional boundary layer surrounding the fiber.Newman's equation, theoretical formula to express the rate of dyeing with the delay was used to calculate theoretical rate of dyeing curve. Boundary layer parameter (L) and diffusion coefficient of dye in fiber (Df) were estimated by fitting the calculated curve to the experimental one. Values of δD estimated under a good stirring ranged in 1.3-4.4×10-3cm. These results obtained revealed that the sorption delay due to diffusional boundary layer is inevitable in dyeing of fiber assembly even if a good stirring is made, particularly for the dyes with high affinity or large Df.Effect of temperature on the barrier action of diffusional boundary layer is discussed briefly.

An azo dye, 2-methyl-N,N-bis(2-hydroxyethyl)-4-aminoazobenzene (nonionic dye) and its conjugate acid (cationic dye) are simultaneously adsorbed by the cellulose membranes carrying sulfonic acid groups from a slightly acidic aqueous solution. Sorption equilibria of the nonionic and the cationic dye are described in terms of the Henry's partition and the ionic exchange mechanism, respectively, in the latter case, the ion exchange constants obtained for the membrane with sulfonic acid group content (SAG) = 261 meq/kg at 30°C are K = 1.43 × 10−5 and K = 0.542, respectively, where Na, H, and DH refer to sodium, hydrogen, and cationic dye ions. The diffusion coefficients of the nonionic dye (DN) and the cationic dye (DC) in the membranes were estimated from the permeation data of the dyes through the membrane. Both DN and DC decrease with increasing SAG. The ratio DN/DC ranged in 2.2–10, the ratio increases with the SAG.

A mixing-reaction model ‘MIRE-CSTR’ is developed to describe the selectivity behaviour mixing-disguised reactions in continuous stirred tank reactors (CSTR). For competitive, consecutive reactions the general behaviour is demonstrated and a comparison with the behaviour in discontinuous operation is made. Furthermore, the start-up process of the CSTR is discussed with the help of a model similar to the model ‘MIRE-CSTR’.

1-Arylazonaphthalenes with all the potential cyclopalladation sites (one peri- and three ortho-positions) substituted by methyl or ethyl groups react with stoicheiometric or catalytic amounts of sodium tetrachloropalladate(II) to the corresponding 2-arylbenzo[g]indazoles. Possible mechanisms for the catalytic cyclization reaction are proposed.

A mixing-reaction model (MIRE) is used to develop criteria, readily accessible by experiment, which permit the chemist to decide whether and when mixing effects influence the product distribution in competitive consecutive or parallel reactions. The validity of these criteria is demonstrated by comparison of prediction and experiment in the examples used.