Microdistributions of Electrolytic Alloys and Their Components

Microdistributions of Cu–Ni and Cu–Co alloys electrodeposited from pyrophosphate; Ni–Cu, from sulfate–chloride and pyrophosphate–ammonium; Cu–Zn, from pyrophosphate and cyanide; Cu–Cd, from sulfate and pyrophosphate; and Ni–Cd, Ni–Co–Cd, and Zn–Cd, from sulfate, sulfate–chloride, pyrophosphate, chloride–ammonium, and acetate electrolytes are studied. The coatings' microprofile depends on the kinetics of reduction of each component and mutual influence of electrochemical processes at the cathode. Copper accelerates and cadmium inhibits the reduction of the second component of alloys, no matter the electrolyte type, reduction kinetics, and metal nature. In antileveling conditions, the diffusion-controlled Cu reduction accelerates the reduction of the second component of alloys and ensures deposition of coatings whose microprofiles are more uniform than expected from diffusion limitations only. Depolarizing action of Cu during the Cu–Zn deposition from a cyanide electrolyte can completely neutralize differences in the rates of supply of reduced metal ions; hence a constant chemical composition of the coating over its microprofile. Inhibiting action of the diffusion-controlled Cd deposition provides for leveling properties of electrolytes from which Ni–Cd, Ni–Co–Cd, and Zn–Cd alloys are deposited; the chemical composition of these deposits is nonuniform over their microprofiles.     

Adsorption characteristics of chloroform on modified zeolites from gaseous phase as well as its aqueous solution

Adsorption characteristics of chloroform from its aqueous solution on Na–Y and Li–Na–Y modified by SiCl₄ were measured and compared with those on Na–ZSM-5 and Na-Mordenite.No adsorption occurred on Na–Y with high hydrophilicity, while the siliceous faujasites became capable of adsorption and its amount increased with increase in the Si/A1 ratio. Adsorption isotherms are of Langmuir type, suggesting that adsorption proceeds by pore filling. The adsorption amounts expressed in volume on Na–Y with high hydrophobicity corresponded to their pore volumes.Adsorption characteristics of chloroform from gaseous phase on Na–Y with different Si/A1 ratio were also measured. The adsorption capability decreased with increasing Si/A1 ratio.Immersional heats of zeolites into water or chloroform were measured in order to evaluate the surface affinity to both solvents. Immersional heats into water were almost constant (about 500 mJ·m^–2) for zeolites with their Si/A1 ratio below 10. The heats decreased with an increase in the Si/A1 ratio above 10, then became almost constant (about 120 mJ·m^–2) over 30 in their ratio. Heats of immersion of Na–Y series into chloroform were almost constant irrespective of their Si/A1 ratio, but decreased slightly when the ratio exceeded 20.Adsorption characteristics of chloroform could be well related to immersional heats into both solvents.     

Researches on 2, 1, 3-thia- and selenadiazole

4-Hydroxy-, 4-hydroxy-5-methyl-, 4-hydroxy-7-methylbenzo-2,1,3-thiadiazoles are polymorphous.4-Hydroxybenzo-2,1,3-thiadiazole (I), 4-hydroxy-5-methyl- and 4-hydroxy-7-methylbenzo-2, 1, 3-thiadiazoles (II and III) melt at 114–115°, 110–112°, 100–102° C, respectively, after recrystallization from water [2–4], but after recrystallization from petrol ether [5] they melt at 128–129°, 124–125°, and 119–120° C [5]. In this connection we recrystallized these phenols repeatedly from petrol ether after recrystallizing them from water, and their melting points rose as expected [5]. On the other hand, the compounds with melting points 128–129°, 124–125°, 119–120° C (ex petrol ether), after repeated crystallization from water melted at 114–115°, 110–112°, 100–102° C, respectively.For Part XXXVIII see [1].     

Physicochemical Study of New Mono- and Binuclear Copper(II) Complexes with Sterically Hindered Acylhydrazones and Azomethines

Series of new binuclear copper(II) complexes with acylhydrazones and azomethines of substituted derivatives of salicylaldehyde containing bulky tert-butyl substituents were synthesized. The target dimerization of the monomeric fragments of the complexes caused by the steric factors was shown to predetermine the specific features of their magnetochemical behavior. The calculated exchange parameters for the complexes based on acylhydrazones range from –110 to –138 cm^–1 and those for the complexes based on azomethines lie in the interval from –400 to –500 cm^–1.     

ZnO nanorods decorated calcined Mg–Al layered double hydroxides as photocatalysts with a high adsorptive capacity

The nanocomposites of magnesium–aluminium–carbonate–layered double hydroxides (Mg–Al–CO₃–LDHs) and ZnO nanorods were prepared via a homogeneous precipitation process. The presence of ZnO nanorods made the calcined Mg–Al–CO₃–LDHs, the strong adsorptive adsorbents for anions, have a photocatalytic activity. Both Mg–Al–CO₃–LDHs and the nanocomposites with various ZnO/Mg–Al–CO₃–LDHs mass ratios from 0.5:1 to 3:1 were characterized by X-ray diffraction, transmission electron microscope and UV–vis diffuse reflectance spectra. The nanocomposites quickly adsorbed the anionic dyes such as acid red G (ARG) without the light illumination, and the adsorbed dyes on the recovered nanocomposites were then degraded in a separated photocatalytic reactor. The adsorption ability of the nanocomposites and their photocatalytic activities for the removal of ARG were evaluated by the Fourier transform infrared spectra and UV–vis extinction spectra. The sample at 3:1 ZnO/Mg–Al–CO₃–LDHs mass ratio was shown to have higher photocatalytic efficiencies.     

Trace elements analysis in rice

Various rice species, marketed in Austria, were analyzed for their Se, Cr, Ni, Rb, Fe, Co, Cs, Ag and Hg contents by neutron activation analysis. The concentration values found for Se ranged between 0.023 and 0.265 ppm, for Cr 0.540–1.875 ppm, for Ni 0.359–0.965 ppm, for Rb 1.604–6.400 ppm, for Fe 24.3–139.8 ppm, for Co 0.026–0.055 ppm, for Cs 0.016–0.032 ppm, for Ag 0.0006–0.0034 ppm, for Hg 0.003–0.023 ppm. Statistical analysis showed in the majority of cases that there is a significant difference in Se, Cr, Ni, Rb, Fe, Co, Hg contents but not in Cs. Highest values of Se and Fe were found in rice from Belgium /long seed, super patna/, whereas the Cr concentration was the highest in rice from Thailand /siam patna/. Ni was highest in rice from Uncle Ben's, Rb in Kresto from USA.     

Synthesis and structure of amino esters of menthol

The conditions for the acylation of (–)-menthol with monochloroacetyl chloride have been studied. Amino esters of (–)-menthol have been obtained by the nucleophilic replacement of the chlorine in (–)-menthol monochloroacetate by residues of secondary amines. Their properties and their mass, IR, and¹³C NMR spectra are described.Institute of Physical Organic Chemistry, Academy of Sciences of the Belorussian SSR, Minsk. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 728–733, November–December, 1981.     

Polarographic investigation of the mobility of halogen atoms in halogen-substituted components of nucleic acids

In order to establish quantitatively the reducibility of halogen-substituted components of nucleic acids, the half-wave potentials (E_1/2) of their electrochemical reduction have been determined. The electrochemical reduction of all compounds takes place in the interval from –0.5 to –1.8 V and consists in the splitting off of the halogen atom (iodine, bromine) from the given molecule. The iodine derivatives are reduced much more readily (500–800 mV) than the bromine derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1404–1408, October, 1992     

Porphyrins

The low and high-resolution mass spectra and the spectra of the metastable ions (DADI) of a number of porphyrins and their copper complexes with –CR=N–R, –CH₂NHR, and –CH₂NRR substituents in the meso position of the porphyrin ring were investigated. The principal pathways of fragmentation of the meso-substituted porphyrins were established.See [1] for communication VI.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 773–779, June, 1978.     

Plutonium-244 dating VI. Initial ratios of plutonium to uranium in achondrites

Re-examination of all known xenon isotopic data for achondrites reveals that²⁴⁴Pu fission xenon can be resolved in about three-fourths of the meteorites of this class. The amounts of²⁴⁴Pu fission xenon found in these meteorites range from ca. 1–2 up to 20–40·10^–12 ccSTP/g. These meteorites started to retain their xenon some 200–500 million years later than did the carbonaceous chondrites Allende, Groznaya, Mokoia, Murchison, Murray, and Renazzo, which began to retain their xenon over 4800 million years ago.