Home – Home – Jornals – Chemistry for Sustainable Development 2007 number 1

A review of the literature data is presented, as well as the results of the own authors' investigations in the area of development of synthesis procedures, studies of the reactivity, and search for the ways of the practical application of mono- and bis-triorganylsilyl derivatives of 1,1-dimethylhydrazine with the general formula R_{4 - n}Si(NH-NMe₂)_n where n = 1-4, and (R₃Si)₂N-NMe₂.

A set of the problems and directions of the accelerated development of the methods of synthesis of fluorine-containing β-sultones by means of the interaction of sulphur trioxide with perfluorinated olefins is considered in connection with the outlooks for their wide use to obtain fluorinated materials for a broad range of practical applications. For instance, they are used as semi-products to obtain polyfluorinated sulpho- and carboxylic acids which are involved in the manufacture of fluorinated membranes for electrochemical processes. The effect of substituents at the unsaturated bond on the formation of a four-membered cycle and the effect of Lewis acids on obtaining unsaturated fluorosulphates. The areas of application are described.

The concentrations of heavy metals (mercury, cadmium, lead, copper and zinc) in needles of Pinus sylvestris growing at the polluted and background territories of the basin of the Selenga River are investigated. The dependence between the metal content of needles and the soil is shown. Using the concentration coefficients for different pollution zones, the rows of metal accumulation in pine needles are arranged; they depict the level of the emission load on forests. In the zone of strong pollution, the highest correlations between the concentrations of lead and cadmium in needles and the morphometric parameters of trees are detected.

Comparative analysis of the element composition of diet and tissues (liver) of the individuals of bank voles (Clethrionomys glareolus) and common shrews together inhabiting chemically polluted (impact) and non-disturbed (background) territories of the Middle Urals was carried out. The obtained data allow one to estimate the role of ecological factors in the formation of biogenic cycles of chemical elements participated by the mammals belonging to different links of trophic chains. The group of phytophages (voles) occupies a special place in the translocation of chemical elements over the trophic levels of mammals. The specific features of feeding for these species and the existence of the gastrointestinal barrier limit the accumulation of elements in animal organisms. Under the same conditions, carnivores (common shrew) play the part of concentrators of a number of chemical elements (Pb, Cd, Cr, As etc.) in the mammal community. The concentrations of these elements increase in the animal organisms in comparison with their concentrations in their food. The toxic load on an animal organism (liver) does not depend on the trophic specialization.

Problems of synthesis and transformations of liquid redoxites have been considered in extraction systems and in systems that contain cations of metals of variable valence. A new method has been put forward to reduce (or to oxidize) cations of d-elements in water solutions of their salts by a liquid redoxite that is present in an organic phase. The procedure can be employed in extraction and separation processes for cations of metals, in the systems where redox processes occur at the phase boundary, and also for organic syntheses that represent a redox process.

The microelement composition of kidney stones in patients from the Novosibirsk and Omsk Regions is investigated. It is shown that the concentrations of elements in kidney stones depends on the mineral phase. The common feature of the kidney stones in the regions under comparison is a broad range of detected elements. It was established by comparing the collections under investigation that heavy elements are dominant in the kidney stones from the Novosibirsk Region; different contents and distribution of microelements in samples are connected with the specific character of the region.

The interaction of NaAl(OH)₂CO₃ · 0.2H₂O (SHAC) with the aqueous solution of 5 M LiCl is investigated. It is shown that a complete transformation of SHAC and the formation of the carbonate form of the double lithium-aluminium hydroxide [LiAl₂(OH)₆]₂CO₃ · nH₂O occur at a temperature of 90 ^oC and interaction time 6 h. The morphological and structural characteristics of the synthesized compound were investigated by means of XPA, high-resolution electron microscopy, and measurements of the specific surface. A scheme of the formation of double Li-Al hydroxide is proposed on the basis of the data of the physicochemical and chemical analyses of the products of SHAC interaction with the aqueous solutions of LiCl.

With the use of literary data, the things on sources of mercury pollution in Siberian region have been considered. With allowance made for present-day data about chemical interactions and with the results of original chemical analysis of crystals, steady atomic groups have been distinguished: [Hg₄O] and [(Hg, M)₄S] tetrahedra (M = Cu, Ag), [Hg₆O₂] r-octahedra, and [Hg₃S₂]_n - the covalent bonded formations of different topology that can be preserved in natural processes, solid-phase and other transformations. This fact should be taken into consideration when discussing the forms of transport for mercury, lead, and alternative toxic elements in the environment.

Features of the spatial distribution of the total content and the forms of zinc and cadmium compounds in the industrially polluted soil cover are investigated. It is established that the maximal accumulation of chemical elements in soil is distributed in the northern and north-western directions at a distance of 250 m from the boundaries of the open-pit mine, while the minimal one is in the east at a distance of 5000 m. A close connection between the concentrations of zinc and cadmium in Artemisia marschaliana sp. and the accumulation of these elements in the soil cover at the Karazhyra coal deposit is discovered. According to concentrating in the top part and in the roots of plants, zinc is characterized by the basipetal distribution and cadmium by the acropetal one.

Analysis has been conducted for 30 samples of atmospheric aerosols on glass-fibre filters with the use of reaction gas chromatography and dry burning method. It has been found that data for the content of total carbon that were obtained with two methods match among themselves within the limits of 30-50 %.

Thermal oxidative degradation of poyacroleinoximes that have been obtained by condensation of polyacroleins that contain as much as 80 % of aldehyde groups, with hydroxylamine has been studied. In response to differential thermal and isothermal analysis as well as to IR and mass spectrometry, it has been demonstrated that the process of thermal oxidative degradation of poyacroleinoximes to a large measure depends on their heating rate and to a lesser degree, on the molecular mass and on the structure of polymers. It has been found that dehydration of oxime groups and N-hydroxy piperidine cycles is observed in a temperature range from 120 to 250 ^oC at the heating rate up to 4 ^oC/min (on evidence of DTGA, as well as based on the results that have been received in the study of thermal oxidative and thermal degradation under the isothermal regime at 170 and 190 ^oC), which gives rise to acrylonitrile units in the macromolecules, these units being capable to intra- and intermolecular cross-linking. Thus, heat treatment of poyacroleinoximes at 190 ^oC under the isothermal regime may yield heat resistant polymers. With increased heating rates for poyacroleinoximes, being as large as 5 ^oC/min and higher, the destruction becomes complicated even at 170 ^oC due to oxidizing detachment of lateral groups that make up the macromolecules of polymers, probably, at the expense of a chain process initiated by nitroxyl radicals. This yields a hydrocarbon polymeric residue that contains conjugated -С=С- bonds in the macrochain and that is burnt down in a temperature range of 400-600 ^oC.

In the samples of bottom sediments of the Gulf of Finland in its eastern part, 43 organic compounds containing sulphur were identified and estimated quantitatively by means of gas chromatography - mass spectrometry. It is shown that polysulphides are widespread in the bottom sediments of the investigated part of the Gulf of Finland. An increase in the concentrations of sulphur-containing compounds with an increase in the salt content of water and with an increase in the depth of the gulf from the east to the west was detected. The high concentration of sulphur-containing organic compounds in bottom sediments in the region from the west edge of the island of Kotlin to 28 degrees of eastern longitude provides evidence that there exist the conditions for the formation of hydrogen sulphide zones stable in this region.

Steam conversion of dimethyl ether (DME) into a hydrogen-bearing gas on bifunctional СuO-CeO₂/
γ-Al₂O₃ catalysts that contain superficial sites that afford passing the reactions of DME hydration and steam conversion of methanol have been investigated. It has been demonstrated that the catalysts offer a high activity and selectivity in steam conversion of DME. Their productivity with respect to hydrogen comprises 0.47-0.61 mol Н₂/(g_cat · h) at 350 ^oC, with the feed rate of the reaction mixture being 10 000 h^-1, and at the molar ratio Н₂О/DME being equal to 3. As this takes place, the volume fraction of CO in the generated hydrogen-bearing gas is substantially lower than the equilibrium value and it does not exceed 1 %.