Synthesis in the phenothiazine series

The corresponding amines were obtained by reduction of 1-nitro-3-bromophenothiazine and 2-bromo-4-nitrophenothiazine. 1-Amino-3-bromophenothiazine reacts with formic acid to give 4-bromoimidazo[4,5,1-k, l ]phenothiazine and with carbon disulfide to give 4-bromo-1,2-dihydroimidazo [4,5,1-k, l ]phenothiazine-1-thione. 4-Aminophenothiazine reacts with sulfur and carbon disulfide to give 2, 3-dihydrothiazolo[5,4-c]phenothiazine-2-thione.See [1] for communication XXXIV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 202–203, February, 1974.     

Decomposition and Oxidation Reactions of Aliphatic Nitro Compounds in Supercritical Water

The reaction kinetics of nitromethane, nitroethane, and 1-nitropropane decomposition and oxidation in supercritical water near the critical point was studied in a flow reactor. The reaction rate constants were calculated assuming first-order reaction. It was found that pressure has a considerable effect on the rates of decomposition of the above nitrogen-containing compounds in supercritical water over a wide pressure range. The reactivity of the above aliphatic nitro compounds in supercritical water in decomposition reactions decreased and in oxidation reactions increased with an increasing number of carbon atoms.     

The thermodynamic characteristics of formation of nanoparticles from supercritical solvents

A thermodynamic model for calculating equilibria and the phase states of fluid-solid systems over wide temperature, pressure, and composition ranges was suggested. Calculations were performed to determine the parameter regions where a substance was isolated in the form of a solid depending on the chemical composition of the initial mixture and the amounts of and ratio between the solvent and antisolvent in it. The calculations were performed for a model system containing ethanol, carbon dioxide, and phenanthrene. The rapid expansion of this supercritical fluid was simulated to model the conditions of the formation of a solid (phenanthrene) and nanoparticles based on it. It was shown that the selection of the state parameters of the supercritical mixture determined the optimum conditions of solid state formation as the fluid expanded.     

Adsorption of Ions on the Surface of Tin Dioxide and Its Electrokinetic Characteristics in 1 : 1 Electrolyte Solutions

Adsorption and electrokinetic characteristics of tin dioxide (cassiterite) are studied as a function of pH in aqueous NaCl and KCl solutions. The dissociation constants of surface groups, formation constants of ion pairs, and the adsorption potentials of ions are calculated in terms of the 2-pK model; capacities and potentials of the electrical double layer are determined; the dissociation degree of surface groups in the point of zero charge and in the isoelectric point are also estimated. It is shown that the 2-pK model in combination with the Graham model can be applied in the studied systems for describing the experimental results.     

Kinetics and Isotherms of Cationic Polyelectrolyte Adsorption on Quartz

The kinetics of the formation of quartz surface charge in the solutions of a cationic polyelectrolyte, poly(styrene-co-dimethyl aminopropylmaleimide) with the molecular mass M = 20000 is studied in the concentration range from 10^–5 to 0.5 g/l in 10^–4 M KCl background solution at pH 6.5. Quartz capillaries with the radius from 5 to 10 m and molecularly smooth surface are used as model systems. Characteristic times of the formation of the surface charge at equilibrium with the solution are calculated from the data on the kinetics of adsorption; these times are equal to 40–50 min for the region of electrostatic adsorption (before the surface charge reversal) and 20–25 min, for the region of hydrophobic adsorption upon the formation of the second adlayer. Based on the steady values of the surface charge, the isotherms and potentials of adsorption of cationic polyelectrolyte are calculated. Electrostatic adsorption isotherm is described by the Langmuir equation with the energy of molecular adsorption of 25.4kT. It is shown that, at polymer concentration above 10^–2 g/l, the conformation of adsorbed molecules ceases to be planar. However, even in this case, we succeed in calculating the surface charge using the Helmholtz and Gouy equations and applying the pressure drops at the capillary ends higher than 10 atm, when under the loading of increasing shear stress in the surface layer the conformation of adsorbed molecules approaches the planar shape. Based on the two-layer model of the formation of surface charge developed earlier, it is shown that the energy of hydrophobic adsorption is smaller than that of electrostatic adsorption and is equal to 17.7kT. Possible physical mechanisms of electrostatic and hydrophobic adsorption of cationic polyelectrolyte molecules on quartz are discussed.     

The Effect of Thermal Treatment on the Structural and Electrokinetic Properties of Porous Glass Membranes

The properties of porous glass membranes prepared by acid leaching of sodium borosilicate glasses 8B and 8V and also 8B glass containing small amounts of fluorine and phosphorus (SFP) are comprehensively studied. The effect of the composition and conditions of thermal treatment of the original and porous glasses on their structural (specific surface area, structure resistance coefficient, average pore radius, volume porosity, and filtration factor) and electrokinetic characteristics (conductivity, counterion transport numbers, and electrokinetic potential) in KCl solutions at neutral pH values is studied. It is shown that an increase in thermal treatment temperature T _TT of the porous glasses from 120 to 750°C leads to a decrease in structure resistance coefficient β of 8B membranes. For membranes prepared from SFP glass, β values, efficiency coefficients, and counterion transport numbers are virtually independent of T _TT at 120–600°C and increase at T _TT = 750°C. Specific surface area and volume porosity decrease with a rise in T _TT for all studied membranes. The observed regularities of variations in the membrane characteristics are explained by the increasing fraction of large pores because of sintering of small pores with an increase in T _TT and by the different amounts of secondary silica in the pore space of porous glasses.__________Translated from Kolloidnyi Zhurnal, Vol. 67, No. 3, 2005, pp. 299–307.Original Russian Text Copyright © 2005 by Volkova, Ermakova, Sidorova, Antropova, Drozdova.     

Silver nanocomposites based on a copolymer of 1-vinyl-1,2,4-triazole with crotonaldehyde

New polymer silver nanocomposites were synthesized using a copolymer of 1-vinyl-1,2,4-triazole with crotonaldehyde as the silver ion reducing agent and stabilizer of metal nanoparticles. The formation of the metallic phase in the nanoscale state was confirmed by UV spectroscopy and X-ray phase analysis. According to the transmission electron microscopy, nanoparticles have sizes of 2—14 nm and are uniformly distributed in the volume of the polymeric matrix.     

Evolution of the <Emphasis Type="Italic">N</Emphasis> = 40 neutron subshell in 20 ≤ <Emphasis Type="Italic">Z</Emphasis> ≤ 30 nuclei within the dispersive optical model

The evolution of single-particle neutron spectra in the N = 40 isotones ⁶⁰Ca, ⁶²Ti, ⁶⁴Cr, ⁶⁶Fe, ⁶⁸Ni, and ⁷⁰Zn is calculated on the basis of the mean-field model featuring a dispersive optical potential. The results of these calculations agree with the idea that the degree of collectivity becomes higher in the ⁶⁴Сr nucleus and that the coupling of single-particle motion to this collectivity becomes stronger, as well as with available experimental data, which are indicative of the closure of the N = 40 subshell in ⁶⁸Ni and of the trend toward this closure in ⁶⁰Ca.     

Layer-to-layer adsorption of oppositely charged polyelectrolytes: The effect of molecular mass: 1. Formation of the first layer

The formation and properties of adsorption layers of poly(dimethyldiallylammonium chloride) with different molecular masses on the surface of fused quartz are studied by the capillary electrokinetics method. It is shown that the value of ζ potential depends on the flow rate of liquid determined by the pressure drop. Such behavior can be explained by the deformation of the adsorption layer. At low rates of liquid flow, constant values of adsorption and time needed to achieve these values decrease for the samples of lower molecular masses, which is probably related to the more closely packed structure and, hence, to the lower deformability of the adsorption layers, as well as to the shortest times during which conformational rearrangements proceed in the layer. The time of conformational changes in the adsorption layer significantly exceeds the time of adsorption. The adsorption of cationic polyelectrolyte is irreversible. It is found that the compaction of adsorption layers increases with time; the rate of compaction of layers of a low-molecular-mass polyelectrolyte is higher and the layers of a high-molecular-mass polyelectrolyte retain the residual deformability even for six days. The measurements of the filtration of polyelectrolyte solutions through thin quartz capillaries allow the thickness of adsorption layers and their deformation under pressure to be estimated.     

Structural and electrokinetic characteristics of ultra-and nanoporous glasses in tetraethylammonium chloride solutions

The structural and electrokinetic characteristics of ultra-and nanoporous glasses produced from basic sodium borosilicate glass have been investigated in tetraethylammonium chloride solutions. Colloido-chemical characteristics of the membranes have been compared with those determined in sodium and potassium chloride solutions. It has been found that the regularities of variations in counterion transference numbers and efficiency coefficients are related to a decrease in tetraethylammonium cation mobility in the membranes.