Home – Home – Jornals – Chemistry for Sustainable Development 2007 number 5

Promising methods are reviewed for obtaining N-, O- and S-derivatives of arenes and N-hetarenes useful from synthetic and applied standpoint (both substituted and unsubstituted) via direct heteroatom chloroalkylation, those contain either mono-, di- or trichloroalkyl group in the alpha position with respect to the heteroatom. The cloroalkylation reactions are systematized according to a particular reaction mechanism (free radical, carbene, nucleophilic or electrophilic one).

The complex of problems and directions is considered concerning an accelerated development of the methods for the synthesis of fluorine containing benzene derivatives through the action of potassium fluoride on chlorine containing arenes. The use of interphase transfer catalysts (such as hexaethylguanidinium chloride, quaternary ammonium and phosphonium salts, tetra(diethylamino)phosphonium and tetraphenylphosphonium bromides) is shown to be efficient for the obtaining of monofluoro benzene derivatives and polyfluoroaromatic compounds via the action of potassium fluoride on monochloroarenes and polychloroarenes. It is established that the catalytic participation of polyethers (such as dimethyl ether of tetraethyleneglycol, 18-crown-6) in the processes of fluorodechlorination is limited to an increase in the concentration of an "active" fluoride ion. Possibilities are considered for the application of mechanochemical technology for the synthesis of fluoroaromatic compounds via the substitution of chlorine by fluorine in solid phase of chloroaromatic compounds, alkali and alkaline-earth metal fluorides as well as composite mixtures based on them.

Efficient method of the synthesis of 1-alkynyl-substituted derivatives of tetrahydro- and dihydrothebain with the help of Pd-catalysed Sonogashira reaction was developed.

Interaction of guaianolide estaphiatine with dihalogenocarbenes generated from chloroform and bromoform was investigated. It was established that the corresponding halogenated derivatives are formed as a result. Their structure was established by XPA method.

Bibliometric analysis of scientific publications of academician N. N. Vorozhtsov Jr. (1907-1979), the director, founder of the Novosibirsk Institute of Organic Chemistry (NIOCh), Siberian Branch of the Russian Academy of Sciences, has been performed with the use of Chemical Abstracts (CA) and Science Citation Index (SCI) databases (DB) of the STN International scientific and technical network. Comparison with the official list of works has demonstrated that СА DB takes into account 90 % of publications of N. N. Vorozhtsov in 1929-1977. Based on the SCI DB, citation of publications of N. N. Vorozhtsov has been studied and the works most referenced in 1974-2006 have been identified.

Synthesis of o-cyclohexyl-p-thiaalkylphenols of various structure was performed on the basis of 4-hydroxypropyl-2,6-di-tert-butylphenol through a number of intermediate stages. For the synthesized compounds, the rates of their reactions with peroxide radicals were measured. It was shown that p-thiaalkyl-o-cyclohexylphenols are characterized by high antioxidant efficiency and thermal stability and may be used as thermostabilizers of mineral oil and other synthetic materials.

Comparative investigation of the antiradical activity of the nitrones of 3-imidazoline-3-oxide, dihydropyrazine-1,4-dioxide and 2H-imidazole-1-oxide series in the model reactions of initiated oxidation of cumene and methyl oleate in chlorobenzene at 60 ^oC was carried out. For the studied compounds, the rate constants of interaction with the peroxide radicals of cumene and methyl oleate were determined.

Using HPLC, GC and GC/МS techniques, the quantitative total content and mass ratio value for ursolic and oleanolic acids have been determined for Rhododendron adamsii Rehd. leaves and stems as well as for Oxycoccus palustris (cranberry) and Vaccinium praestans Lamb. (press cake).

The qualitative and quantitative content of fatty acids in leaves and stems of Rhododendron adamsii R. has been for the first time studied using gas chromatography and gas chromatography-mass spectrometry. It was shown that the use of preliminary hydrodistillation of plant raw material under investigation allows to remove the compounds interfering the identification and quantitative determination of fatty acids content. There are both non-branched and isostructured fatty acids including polyunsaturated ones containing in plants, with the number of carbon atoms from 12 up to 30 (including odd numbers). Acids with cyclopropane fragment were revealed too, which allows to make the assumption concerning the features of metabolism in this plant. Total content of the acids in leaves is 6.2 mass %, in stems it is amounting to 2.4 mass %.

Catalytic activity of silica gel and aluminium oxide impregnated with sulphuric acid (H⁺-SiO₂ and H⁺-Al₂O₃, respectively) in the reaction of acid-catalysed isomerization of caryophyllen oxide was investigated. It was established that the activity of H⁺-SiO₂ is much higher than that of H⁺-Al₂O₃ and is comparable with the activity of concentrated sulphuric acid. For silica gel H⁺-SiO₂, the dependence between the catalytic activity and the size of silica gel particles was revealed.

A new sesquiterpene lactone of eudesmane series has been excreted from a tournefortia sagebrush (Artemisia tournefortiana Rchb.). The structure of the lactone has been found by the XRD analysis method.

New derivatives of lappaconitine modified in the aromatic and heterocyclic fragments of the molecule were synthesized. Their antiarhythmic activity was studied.

Using the techniques of Gas and High Performance Liquid Chromatography in standardized conditions, chromatographic profiles ("fingerprints") and spectral characteristics were obtained for some compositions of the major biologically active phytogenous substances: hydoxycinnamic acids, flavonoids, anthocyanins, lignanes, flavolignanes. The data obtained can be used for the analysis of group and individual compositions for the identification and standardization of herbal raw material as well as preparations on this base.