Home – Home – Jornals – Chemistry for Sustainable Development 2007 number 4

Sources, methods of isolation, structure and properties of diterpenoids of eunicellane series produced by sea organisms are considered. The schemes of complete synthesis of the urocanates of diterpenoids of 4,7-oxaeunicellane type possessing unique cytotoxic effect are discussed. The known routes of establishing the interconnections between structure and activity in the sarcodictyine series are presented.

The review systematizes the data from scientific publications, patents and Internet resources about the consumer products (preparations) made of the wood green of abies, their biological activity and areas of application. The group chemical composition of extractives from the tree green of abies and the technologies of obtaining them are characterized.

Primary toxicological parameters of fluorine-containing alcohols, dialkyl ethers, acetales, acrylates, esters of carboxylic and dicarboxylic aliphatic acids, epoxides and olefins used as the materials and intermediate products of organofluoric synthesis are considered. The regularities of the effect of fluorine atoms on the toxicity of the compounds are revealed. All the investigated compounds belong to the III and IV class of danger and are safe for developing fluorinated materials on their basis. Some examples of the application of these classes of compounds are discussed.

Dependence of the processes involving reduction of the main components of fixing solutions (silver ions, thiosulphate and sulphite) on silver, graphite and platinum cathodes on pH is investigated. It is established that the pH value has the strongest effect on the reduction of sulphite ion; in the medium with рН ≥ 7 it does not get reduced. Quite contrary, the reduction of thiosulphate and silver is only weakly dependent on this parameter. The optimal electrolysis conditions (potentiostatic mode at the cathode potential equal to 0.85 V, and рН ≥ 7) were chosen so that they allow one to recover the worked out fixing solutions using the flow voluminous porous cathodes and to decrease the residual silver content down to 0.5-1.0 mg/l.

Moulded copolymers of styrene with divinylsulphide were synthesized by means of the living radical polymerisation with N,Nґ-bis(vinyloxyethyl)thiuramdisulphite as an initiator without any solvents. It was shown that the formation of a polymeric body proceeds without the formation of a macrogel. Individual particles of copolymers were discovered using scanning electron microscopy. These particles are monospheroids with a size about 1 μm; they determine further formation of the moulded polymeric body as granules. Copolymer modification was carried out, ionites were obtained. The effect of the nature and concentration of acids on the extraction of silver, gold and platinum ions was established. High distribution coefficients equal to (2.0-6.5) 10⁴ were obtained for the chloride complexes of gold and platinum. The possibility to use sorbents for concentrating precious metals and for analytical purposes was demonstrated. A method of sorbent regeneration was developed.

It was established that deep oxidation of such toxic strong compounds as organometallic pesticides occurs under the action of the system formed by passing the electric current through aqueous solutions of sulphuric acid. On the basis of experimental data, multiparametric equations characterizing the effect of the current density, temperature, concentration of sulphuric acid on the rate of oxidation of the organic fragments of pesticides and metal ion reduction on the cathode were obtained.

Thermodynamic model of the oxidative leaching of sulphide-rich tailings from dressing of gold-containing ores (Berikul settlement, West Siberia) is investigated. When calculating the water - rock interactions, we applied some special approaches allowing one to determine the effect of the degree of reaction progress and change of the parameters of the medium (E_h, pH) on the composition of the formed secondary minerals that restrain the development of acid drainage at the objects of this kind. Substantiation of several stages of the formation of a technogenic system in time and space is presented, depicting the approach of the system to equilibrium with the environment. The distinguished stages correspond to the zoning of mineral associations described at the object. These associations were formed during 50 years of storing the tailing mounds from the lowest weakly oxidized sulphide parageneses with gypsum and covellite to the capping jarosite-quartz-gypsum zones. The results of modelling provide evidence that an increase in rock affection by atmospheric water brings about the conditions favourable for the formation of the "final" association (goethite and quartz); however, this association is not stable even on the surface of the Berikul tailing dump. It is concluded on the basis of preliminary evaluation that hypergenesis processes in the objects of this kind may proceed hundreds of years till complete depletion of the acid-producing and toxic potential of industry-related wastes.

Processes of neodymium sorption from the solutions of neodymium sulphate on the natural clinoptilolite tuff were studied, and the sorption isotherms of neodymium ions were obtained. It was found that neodymium is extracted quantitatively from the dilute solutions (<0.0025 mol/l), but the exchange capacity of tuff in respect to neodymium ions decreases with increasing solution concentration. Kinetic parameters of sorption process were determined.

Sulphur content in the system woody plants-forest litter-soil (the profile-genetic level) was investigated within the boundaries of the urban territory. High accumulation of total sulphur in the needles and leaves of tree species was demonstrated. A substantial depositing ability of the forest litter, upper organics-accumulating and texture horizons of urban soil with respect to the industry-caused sulphur compounds was discovered. A close connection between the sulphur content of tree needles (leaves) and forest litter, as well as the soil profile, was revealed. It was demonstrated that sulphur accumulation in assimilation organs of plants and its physicochemical redistribution in the soil profile might serve as the ground for the adequate evaluation of the degree of industrial load on an urban ecosystem.

The problem of gaseous hydrogen-hydrogen chloride mixture separation with the use of chlorosilanes as sorbents is considered. The possibility of hydrogen purification from HCl up to 0.1 mol. % and its re-entry into the process cycle at the stage of trichlorosilane reduction with hydrogen is demonstrated. The hydrogen chloride purified from admixed chlorosilanes can be used as a reactant for the trichlorosilane production from metallurgical silicon.

Concentrations of polychlorinated diphenyls (PCD) were measured in snow cover (10-520 ng/m²), in the soil (0.3-45 ng/g of dry mass) of Pribaikalia and the southern lakeside, in bottom sediments of Lake Baikal and its tributaries (0.3-3.9 ng/g of dry mass), in Baikalian omul (Coregonus autumnalis migratorious G., 25-41 ng/kg of damp mass). A conclusion concerning the background pollution of the atmosphere of Pribaikalia with PCD at present and the absence of intensive local sources of organic pollutants of this class at this territory is formulated. The concentrations of PCD in soil and bottom sediments remained almost unchanged during the years 1992-2006. The levels of PCD bioaccumulation in Baikalian omul are 3.5-10 times lower than the MPC. Determination of PCD was carried out with the help of gas chromatography-mass spectrometry with the intra-laboratory precision of 7-15 %.

Samples of layered double Mg-Al hydroxides with different Mg/Al ratios were obtained by means of the mechanical activation of the mixture xMg(OH)₂ + yAlCl₃ · 6H₂O with the x/y reagents ratio equal to 3/1, 4/1, 5/1 and 6/1 in a planetary mill AGO-2. It was shown that activation for 25 min with additional mixing and activation for 10 min in the presence of an inert additive KCl allows one to obtain layered double Mg-Al hydroxides without admixtures of initial reagents.

Outlooks for carrying out problem-oriented prospecting investigations and for building up the scientific and technical basis in the area of the efficient use of sapropelite raw material resources.

Data on synthesis routes and the possibilities for modification of the structure of macrocyclic alkaloids of natural origin - derivatives of biogenic polymethyleneamines - are considered and generalized. The data on the synthesis of their synthetic analogues used to develop medical preparations of directed action are also reported.

Analysis of the new approaches to the synthesis of perfluoroolefins and the conditions for performing thermal decomposition of difluorochloromethane and perfluoroalkyl iodides for the synthesis of tetrafluoroethylene and hexafluoropropylene is carried out. Essential simplifications of the technology are stressed. It is established that the production of tetrafluoroethylene is affected by the presence of chlorine and oxygen, the material of reactor walls (quartz glass) and diluter (overheated water vapour). The mechanism of thermolysis is discussed from the viewpoint of the decisive role of difluorocarbene. The possibilities of dehalogenation and dehydrohalogenation of polyfluorohalogenoalkanes in the synthesis of perfluoroolefins and perfluorobutadiene are demonstrated. Decarboxylation of perfluorocarboxylic acids in the production of terminal perfluoroolefins are discussed.

Complex technology of waste utilization of alumina plant, which provides a stepwise going from the stage of statistically controlled accumulation of technogeneous products and impurities to a system of ecologically safety insulation and preservation of wastes, accompanied by the release of products into the processing cycle, is advanced. Starting from the calculated data as the base, this system ensures the highly efficient localization and rendering harmless of the contaminated areas of the hydraulic works by silt deposition based on the highly dispersed SiO₂. The complex technological slime processing in accord with flotation-carbonisation scheme together with neutralization of drainage and slime waters within the regime of carbonisation and clarification make it possible to increase the degree of extraction of the alumina and other valuable components, to reduce the consumption of resources, and to have additional valuable products and additives used industrially.

Composition and changes in the properties of wastewater from the production of diazodinitroquinone as a result of the physicochemical purification are studied for the first time on the basis of UV spectroscopic and chromatographic data. It is established that neutralization of the acid initial wastewater is accompanied by an increase in the molecular chain, while further treatment of the liquid causes a decrease in the length of the molecular chain and the formation of other compounds.

Spring wheat with a high content of selenium has been grown using the complex selenium-zeolite mineral fertilizer. The selenium content varies between 4 and 230 µg/1 g wheat. It has been found that the use of this fertilizer improves the selenium assimilability by wheat from soil as well as increases the wheat mass by 2-11 %.

Indirect electrochemical oxidation of N-methyl-p-aminophenol (metol) with active oxygen generated in situ on graphite cathodes and different metal-oxide anode materials has been studied at different pH. Indirect oxidation of N-methyl-p-aminophenol with active oxygen at different pH values has been demonstrated to result in effective mineralization to СО₂ and Н₂О. In acidic electrolyte in presence of Fe²⁺ ions the oxidation is accompanied with formation of oxalate complexes of iron stable to oxidation.

Supergene processes in the tailings of apatite-nepheline ores have been studied by techniques of physical chemical analysis and thermodynamic modelling. It has been found that under washing conditions characteristic of Kola Peninsula, the finest and lightest particles and the products of hypergenesis are removed by suffosion. Newly formed phases are represented with micas (lepidomelane and gieseckite), amorphous silica, oxides of titanium, manganese, and goethite.

Chelate compounds of maltol, extracted from the needles of Siberian abies, with the ions of such metals as copper (II), cobalt (II), nickel (II), zinc (II), iron (III), aluminium (III), chromium (III) were synthesized. The features of complexation were revealed and the corresponding conditions were optimised. The composition and structure of metal complexes were confirmed with the help of physicochemical and spectral methods UV, IR, NMR), structural characteristics were obtained with the help of EPR. Stability constants were determined; the complexes were arranged into the stability row under the conditions of physiological pH of the medium. The biological activity of ferric and copper maltolates as potential preparations to cure blood diseases was demonstrated.

A process of ultrafiltration purification of water solutions from copper ions with addition of polymer chelating agents of various chemical nature (polyethyleneimine, poly(diallyl dimethylammonium chloride), dextrane, humic acids) has been explored. A possibility to perform a recovery of Cu²⁺ polyethyleneimine complex with the aim to re-use the chelating agent has been demonstrated.

The effect of ozonation and dewaxing of Mongolian high-wax oils on the hydrocarbon type composition of petroleum fractions has been studied. The evolution of composition and properties of straight-run petroleum fractions (IBP 180°C) during reforming on a zeolite catalyst has been examined. It has been demonstrated that after ozonation followed by oil thermolysis the petroleum fractions are enriched with aromatic hydrocarbons while the content of naphthenic ones diminishes. Dewaxing of high-wax oil with liquefied gas has been shown to remove predominantly normal alkanes from petroleum fractions. It has been demonstrated that on catalytic thermal refining of straight-run petroleum fractions the products obtained are depleted of normal paraffin and naphthenic hydrocarbons by 2-5 times, enriched with aromatics by 2-4 times, octane rating of gasoline is enhanced by 18-40 points.

Buffer capacity of the main types of soil of West Transbaikalia with respect to cadmium under different levels of pollution is studied. The dependence of cadmium intake into plants on the buffer capacity of soil is established. The species ability of watercress to accumulate high cadmium concentrations on the soil of different types in the absence of any pollution source is revealed.

A new approach to the synthesis of the natural alkaloid haplamidine and its homologues is developed. The possibility of selective removal of the phthalyl protection by means of hydrazinolysis in the presence of benzoyl group is demonstrated.

Sulphated derivatives have been synthesized around powder cellulose (PC) that was obtained by a procedure of catalytic destruction by titanium tetrachloride. PC involvement in sulphating reaction has been studied as a function of the obtaining conditions. It has been found that sulphates of PC show variable physicochemical properties depending on the obtaining methods.

Results of complex research of sweet, tarry, high-wax oils that occur in lower Cretaceous horizons at Zuunbayan, Tsagan-Els, and Tamsagbulag fields (Mongolia) are presented. With the use of results of physicochemical and radiospectrometric analysis, average values of structural parameters have been calculated for hydrocarbons and high molecular weight heteroorganic compounds inherent in oils.

A study of the potential energy surface of 4-phenyl-1,3-dioxane by non-empirical quantum chemical RHF/STO-3G and 6-31G(d) approximations reveals six energetically inequivalent pathways of conformational isomerization of equatorial and axial chair forms.

Arylamination of 2,4-diethoxycarbonyl-5-hydroxy-5-methyl-3-phenylcyclohexanone affords 2,4-diethoxycarbonyl-5-hydroxy-5-methyl-3-phenyl-N-(3-chlorophenyl)-1-cyclohexenylamine. A distorted semi-chair conformation with psedoequatorial orientation of all substituents except the pseudoaxial ОН-group is established based on the spectral and single crystal XRD data. The presence of an intramolecular N-Н…О=C hydrogen bond is noted.

The dielectric spectra of polypropyleneglycols H-(C₃H₆O)_Nр-OH (PPGs), where N_р = 1, 2, 3, 7, 12, 17, 20, 34, 69, were analyzed in terms of the Dissado−Hill (DH) cluster model above the vitrification temperatures. In PPGs, the structural clusters are associates formed by intra- and intermolecular hydrogen bonds. The activation processes of cleavage and formation of intermolecular hydrogen bonds in clusters, when the total number of intermolecular hydrogen bonds changes, are characterized by the parameter n_DH. The fluctuation processes of simultaneous exchange of molecules between adjacent clusters correspond to redistributions of intermolecular hydrogen bonds between clusters, when only the position but not the total number of intermolecular hydrogen bonds changes, and are characterized by the parameter m_DH. The relaxation time τ_DH at 303 K and 423 K and the parameters n_DH and m_DH of the dielectric spectra were calculated. The activation energies of relaxation in the range 210-323 K were determined. The mean statistic squares of the dipole moments of clusters and di-PG, PPG-425 (N_р = 7), and PPG-2025 (N_р = 34) molecules at 303 K and 423 K were calculated. The number of the units of the oxypropylene chains involved in relaxation was determined. The dependence of the parameters of the DH model, relaxation energies, , and on N_р were studied.

The interaction of the zinc(II) tetra-4-sulfophthalocyanine sodium salt with guanidine polymethacrylate has been studied by electronic absorption (EAS) and IR spectroscopy and viscosimetry. It was found that the reaction between the macroheterocyclic compound and the polymer proceeds due to the binding of the sulfo groups of metallophthalocyanine and the guanidine cation of the polymer, which leads to an extension of the polymer knot and stabilization of its conformation.

Nanosized complexes of ferroparticles with a sensitizer photoditazin (used in photodynamic therapy in oncology) have been synthesized and studied by small-angle neutron scattering. The structure of the complexes was determined, and the influence of the biocompatible polymer pluronic investigated. Clinical tests revealed increased efficiency of the complexes compared with the starting photoditazin. The complexes can be used as the first magnetically operated sensitizer for treatment of oncological diseases by photodynamic therapy.

This paper presents a concise review of the experimental and calculated data reported in the literature on the noncovalent interactions of DNA and proteins with the nonfunctionalized carbon nanotubes. Our Raman scattering and electron microscopy data on carbon nanotubes and SEIRA spectral data on changes in the conformational state of the main biological polymers (DNA, PolyА, BSA, and RNase А) in reactions with single-shell carbon nanotubes allowed us to define the character of noncovalent interactions in the tube−biomolecule system. An analysis of the data showed that reactions of DNA with nanotubes lead to the binding on the surface of the nanotube and form stable complexes with van der Waals interactions, in which π stacking plays the major role and which changes the hydrogen bonds in the biological molecule with structure rearrangements. Albumin and RNase А are presumably adsorbed at the conventional binding sites of these proteins on the nanotube with participation of hydrophobic interaction and π stacking, as indicated by structure rearrangements in proteins.

The paper presents a simple method for fixing DNA and synthetic polyions on the surface of p and n type Si(100) single crystals. Different methods for preparing the surface for DNA fixation are compared. It is shown that the conformation of macromolecules fixed on a substrate depends on the presence of bivalent counterions in solution and the charge properties of the surface and polymer. The results of fixation were checked and analyzed by atomic force microscopy (AFM).

The conformational changes of DNA in aqueous solutions containing ethanol and iso- and n-propanol having concentrations of 0-23 wt.% and ionic strength μ = 0.003 М NaCl and exposed to γ radiation at doses from 0 Gy to 30 Gy were studied by low-gradient viscosimetry and circular dichroism. The dependence of the specific volume (V_sp) of DNA on the radiation dose changed at different contents of alcohol. There is a critical concentration (С_cr) at which the structure of the mixed solvent is rearranged. The V_sp of DNA decreased as the radiation dose increased at С_alc = 12 wt.% < С_cr and increased at С_alc = 23 wt.% > С_cr. In both cases, the largest V_sp of DNA was observed in water−ethanol solutions. The secondary structure of the macromolecule in the systems corresponds to the В form. It was shown that the observed conformational changes in irradiated DNA at С_alc < С_cr and С_alc > С_cr could not be explained only by the ability of alcohols to intercept the ОН radicals formed in radiolysis of water.

The stage of noncooperative interaction of the chromosomal nonhistone protein HMGB1 with DNA has been studied by spectroscopic methods and gel retardation. It was found that complexation was accompanied by compaction of the DNA molecule over a wide range of protein/DNA ratios in the complex. A circular dichroism study showed that the binding with DNA changed the secondary structure of the HMGB1 protein. Changes in the structure of the protein start under the conditions of an excess of binding sites on DNA and end at a ratio of ~40-50 base pairs per protein molecule, the α-helicity of HMGB1 in the complex increasing by 20% compared with the free state. It is believed that the change in the secondary structure of HMGB1 during the binding with DNA underlies the mechanisms of the various functions of this protein in the cell.

The effects of the structural characteristics of dihydrofolate reductase (DHFR) inhibitors on their tuberculostatic activity have been analyzed. It was shown that an increase in the electron density on bonds and atoms in the ring led to an increase in the biological activity of the compounds. A correlation was found between the biological activity and the characteristics of the critical points of electron density of bonds. The 3D- and 4D-QSAR studies with the CiS algorithm revealed the pharmacophore and antipharmacophore fragments of DHFR inhibitors, and regions of the receptor that are responsible for the biological action of dihydropyrimidines were found. Receptor−ligand complexes were modeled. For a series of drugs containing a podand chain, it was found that the chain performed only the transport membranotropic function because the increase in the size of molecules due to the podand chain gives rise to steric hindrances when the chain is built in the receptor cavity.

The interactions of DNA with phenoxazones, xanthones, and carbazoles containing the (benzo-18-crown-6)-4′-yl and (benzo-15-crown-5)-4′-yl radicals bonded to the chromophore via spacers of different lengths in the presence of Na⁺ and K⁺ ions were studied by spectrophotometry, circular dichroism, and dynamic birefringence. The thermodynamic parameters of the binding of the compounds with DNA and changes in the macromolecular parameters of the DNA molecule during complexation were determined. Based on the results of these studies, we suggested the models of bonding of these compounds to the double helix of DNA. It is shown that the mode of DNA binding with a phenoxazone derivative containing two (benzo-15-crown-5)-4′-yl radicals bonded via a fragment of glycine to chromophore depends on the type of the counterion in solution. In the presence of Na⁺, the chromophore is intercalated into the double helix of DNA; in the presence of K⁺, it is bound to DNA in the form of a dimer outside the double helix. The type of the counterion does not affect the mode of binding of other crown-containing compounds of actinocin with DNA. For compounds containing the (benzo-18-crown-6)-4′-yl radical, the mode of binding to DNA зdepends only on the spacer length.

The interactions of palladium cation−anion compounds (C₄H₁₀NO)₂[PdCl₄], K₂[PdCl₄], and K₂[PdBr₄] with DNA in 0.005 M NaCl and 0.15 M NaCl solutions were studied by spectrophotometry, circular dichroism, viscosimetry, dynamic birefringence, and atomic force microscopy. The interactions are primarily effected by coordination of the donor atoms of DNA bases by palladium. The end products of interactions with palladium acido complexes are independent of the macromolecule and the nature of halogen X in [PdX₄]^2-. The significant changes in the conformation of DNA in palladium complexes resulted from both intra- and intermolecular cross-linkings induced by palladium.

The site effect (the dependence of the band intensity on the band position of gel) is the key factor that should be taken into account in quantitative analysis of the images of high-resolution electrophoretic gels containing many bands. We developed two procedures for taking this effect into account. The dependence of the relative frequencies of internucleotide bond cleavages on the type of nucleotide, obtained in the analysis of the splitting patterns of DNA fragments under the action of ultrasound or chemical factors, was evaluated by а) using the linearly sliding mean; b) describing the function of the site dependence as a third degree polynomial. The methods lead to similar results. An analysis of the splitting of different sequences, whose total length was more than 20,000 nucleotides, allowed us to determine the relative frequencies of bond cleavages in all 16 dinucleotides found in a DNA sequence. In ultrasonic treatment, the phosphodiester bond, lying between cytosine and guanine, undergoes cleavage more often than the corresponding bonds between other nucleotides in the sequence.