Home – Home – Jornals – Chemistry for Sustainable Development 2011 number 6

Results obtained by the authors in the investigations in the area of synthesis and examination of the antioxidant properties of polyfunctional water-soluble antioxidants based on alkylated phenols are presented in the review. The promising character of the use of synthesized compounds for corrections of pathological states connected with the development of oxidative stress is demonstrated.

An approach for the determination of the individual and the group composition for low molecular mass organic substances of natural and anthropogenic origin basing on the analysis of chromatographic profiles (“fingerprints”) and the spectral characteristics. Data are presented concerning the use of the approach for the identification of persistent organic pollutants in the environment of Siberia and Mongolia with the purpose of assessing the risk of the chemical compounds to affect human health and ecosystems, as well as of identifying the main sources of pollution. There are potentialities considered concerning the approach for the analysis of biologically active substances of plant or animal origin, the development of low-dose preparations for agriculture biomass based on Siberian coniferous plants as well as the studies of living systems. It is demonstrated that chromatographic profiles represent highly informative characteristics those could be used in order to recognize a “chemical image” of complex systems, to identify and predict properties inherent in these objects.

Possibilities to use superacids for the synthesis of optically active natural compounds are analyzed in the review. The revealed regularities of cationoid rearrangements of terpenoids under the conditions of super-nucleophilic media and low temperatures are taken into account. Mono- and sesquiditerpenoids and their analogs are chosen as the subject of investigation. Results of works published since 1984 till 2004, including those supervised by Prof. V. A. Koptyug, are reviewed.

A simple method of bromination with a high yield is proposed for severely deactivated aromatic compounds, such as 1,3-dinitrobenzenes and polycyclic nitro compounds. The method proposed is based on the action of bromine in sulphuric acid in the presence of nitric acid. The reaction stoichiometry corresponds to the consumption of 0.5 mol of bromine and 0.5 mol of nitric acid per 1 mol of an aromatic substrate. The nature of the bromination agent is under discussion.

The interaction of bis(tetrafluoroborate) of 1-fluoro-4-chloromethyl-1,4-diazoniabicyclo[2.2.2]octane (F-TEDA-BF₄) with phenol, acetanilide and their derivatives, resorcinol, 1-, 2-naphthols and 6-methoxyquinoline in water was investigated. In some cases, fluorination of aromatic compounds in water proceeds more selectively than in the case when organic solvents are used.

For three 6′-cyano-substituted spironaphthooxazines (SNO), photochromic properties were revealed in the films obtained from melts. Quantum yields were determined for the forward and reverse photochemical reactions. Unlike phenanthroline-containing spirooxazines, SNO polycrystals do not exhibit photochromic properties.

The ability of glycyrrhizic acid to form complexes with the products of cholesterol oxidation was studied. The effect of complexing on the rate of cholesterol oxidation with ozone was studied. It was shown that the formation of complex with glycyrrhizic acid may become an efficient approach to govern the level of cholesterol inside and outside of cell membranes, and to extract the products of cholesterol oxidation.

An attempt is made to systematize the data from scientific publications, patents and the internet resources concerning triterpene components in the plants of Pinaceae family those could be considered as chemotaxonomic markers and as the active principle of biologically active preparations. Examples are given for the major structural groups of triterpenoids inherent in conifers and data concerning the presence of these compounds in total extractive substances of the plants of different genera of the family. A problem connected with the examination of bioactivity of triterpenoids inherent in coniferous plants is assessed.

Convenient methods of the synthesis of new perfluoroaromatic monomers of BB and AB types and polyimides on their basis were developed. The effect of the structural factors (the nature of aromatic framework, substituents and bridges, isomerism) on the reactivity of monomers and major characteristics of polyimides was discussed. It was established that the obtained polyimides possess promising properties for optoelectronic applications.

Features of a number of chemical reactions in the absence of solvents under microwave action were investigated. The features of microwave heating of phthalic anhydride and glycine before and after melting were studied. It was shown that the microwave synthesis of glycine phthalimide occurs efficiently and with the high yield in the reaction mixture heated above the melting point of phthalic anhydride. Decomposition of intercalation compounds of chlorine trifluoride and intercalation compounds with acetone, acetonitrile, benzene and carbon tetrachloride implanted into the interlayer space of dicarbon polyfluoride was investigated. It was shown that the decomposition of intercalation compounds under microwave heating resulting in the formation of nanostructured graphite occurs at lower temperature values than those involved in conventional convection heating. It was concluded on the basis of experimental results that the absorption of microwave energy is connected with the dielectric properties of the substances intercalated into the interlayer space of dicarbon polyfluoride matrix. Experiments were carried out with Explorer-48 set-up with the microwave unit Discover S-class (CEM Corporation, the USA) operating at the frequency of 2450 MHz under the conditions of controlled power of microwave action within the range 0–300 W.

It was established that 9α,14α-epoxy-14α-desoxyecdysteroids (oxetanoecdysteroids) formed from the corresponding ecdysteroids in the solutions of alkaline metals in liquid ammonia undergo molecular rearrangements catalyzed by acids. As a result of these rearrangements, 9α,13α-epoxy-14β-methyl-13β-demethyl-14α-desoxyecdysteroids and 9α-hydroxystachisteron В are formed. The reduction of oxetanoecdysteroids by sodium borohydride results not only in the reduction of 6-keto group but also in the rearrangement of the oxetane cycle. The oxetane molecular rearrangement also takes place during catalytic hdyration of Δ⁷-bond in oxetanoecdysteroids.

On the basis of bromopropyl-, mercaptopropyl- and allyl-substituted phenols, the synthesis of ω-[3-(4-hydroxyaryl)propylthio]alkalic acids was carried out. It was shown in the model reaction of methyl oleate autooxidation that the synthesized ω-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propylthio]alkanoic acids exceed phenosan antioxidant in the antioxidant activity due to the presence of sulphide groups in their structure.

Cyclization of vic-alkynyl-substituted diazonium salts in the series of anthraquinone, naphthoquinone and benzene was studied. Basing on experimental data and the results of quantum chemical calculations, a scheme of heterocyclization mechanism was proposed for vic-(alkynyl)arenediazonium salts. The scheme proposed is fundamentally different from the generally accepted scheme of the Richter reaction mechanism.

The processes of joint mechanical activation of some benzimidazole antihelminthic preparations with water-soluble polymers in the mills of shock-attrition type were studied. The conditions of synthesis of supramolecular complexes with different components ratios and energy strain of activator mills were discussed. The products of mechanochemical synthesis were characterized on the basis of water solubility and particle size. The products obtained possess higher water solubility and smaller particle size than the initial benzimidazole compounds; the products are of interest as potential antihelminthic preparations with increased efficiency.

Photodegradation of herbicide 2,4,5-trichlorophenoxyacetic acid (2,4,5-Т) in aqueous solutions was studied by means of steady-state and nanosecond laser flash photolysis. It was demonstrated that the primary photochemical act involves one- and two-photon ionization of the herbicide and the formation of the hydrated electron/radical cation pair. In oxygen-free solutions, hydrated electron disappears due to capturing by the initial compound, whereas the radical cation gets hydrolyzed with water to form a long-living phenoxyl radical. We also studied the formation of 2,4,5-Т complexes with β- and γ-cyclodextrins (2,4,5-Т-β(γ)-CD) and the effect of this process on the rate of the steady-state photolysis of the herbicide.