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Showing papers in "Russian Chemical Bulletin in 1997"


Journal ArticleDOI
TL;DR: In this paper, the main types of self-propagating high-temperature synthesis (SHS) technology and their application for the preparation of new compounds, materials, and items along with technical and economical effectiveness are considered.
Abstract: The review is devoted to the problem of self-propagating high-temperature synthesis (SHS). The fundamentals of SHS are briefly considered, the most promising results of the experimental diagnostics and modeling of SHS processes are presented, new nonlinear phenomena and the data of thermodynamic calculations, as well as kinetic and macrokinetic studies are discussed. The main types of the SHS technology and their application for the preparation of new compounds, materials, and items along with technical and economical effectiveness are considered. New directions and perspectives of SHS are discussed.

57 citations


Journal ArticleDOI
TL;DR: The results of NMR-spectroscopy studies of the structure, dynamic stereochemistry, and intermolecular interactions in solutions of organic derivatives of penta-and hexacoordinated silicon, germanium, and tin containing amidomethyl, lactamide, and related bidentate ligands are surveyed in this paper.
Abstract: The results of NMR-spectroscopy studies of the structure, dynamic stereochemistry, and intermolecular interactions in solutions of organic derivatives of penta-and hexacoordinated silicon, germanium, and tin containing amidomethyl, lactamomethyl, and related bidentate ligands are surveyed.

56 citations


Journal ArticleDOI
TL;DR: In this article, the data on the molecular design, spectral properties, photochemistry and complexation of photochromic crown ethers containing a C=C bond are described systematically and generalized.
Abstract: The data on the molecular design, spectral properties, photochemistry and complexation of photochromic crown ethers containing a C=C bond are described systematically and generalized. Prospects for the practical application of these compounds are considered.

42 citations


Journal ArticleDOI
TL;DR: In this article, the valence state and coordination of metals were studied and the methods for their synthesis were optimized, and the results showed that the strong antiferromagnetic exchange (μelf=1.41 and 0.34 μB at 290 and 80 K respectively) was detected in CuII itaconate.
Abstract: Acid and neutral CoII, CuII, NiII, ZnII, FeII, and FeIII maleates, fumarates, and itaconates were obtained and characterized. The methods for their synthesis were optimized, and the valence state and coordination of metals were studied. CoII and FeII hydrogen maleates, CoII maleate, and CoII fumarate were examined by X-ray diffraction analysis. The ligands based on unsaturated dicarboxylic acids can be mono-, bi-, and tetradentate, which results in the formation of acid salts, chain and three-dimensional coordination polymers, whose double bond is not involved in the coordination. The strong antiferromagnetic exchange (μelf=1.41 and 0.34 μB at 290 and 80 K, respectively) was detected in CuII itaconate. Based on the data of Mössbauer spectroscopy, the partial reduction of FeIII to FeII during the synthesis of FeIII maleate was shown to occur: δFe=0.43 and 1.27 mm s−1, ΔEQ=0.57 and 3.13 mm s−1 and Γ=0.37 and 0.28 mm s−1 atT=298 K for FeIII and FeII, respectively.

35 citations



Journal ArticleDOI
TL;DR: In this paper, the main product of the hydrogenation of fullerene C60 is C60H36, which is sufficiently stable and contains four isolated benzenoid rings located at tetrahedral positions on the surface of the molecule.
Abstract: Fullerene hydrides were prepared by hydrogenation of fullerences C60 and C70 using proton transfer from 9,10-dihydroanthracene to fullerene and were studied by mass spectrometry (electron impact, field desorption), IR, UV, and1H and13C NMR spectroscopy. The main product of the hydrogenation of C60 is C60H36, which is sufficiently stable. Hydrogenation of fullerene C70 gives a series of polyhydrides C70H n (n=36–46), and the main product is C70H36. The dehydrogenation of C60H36 by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone is not quantitative and results in the formation of fullerene derivatives along with C60. The comparison of the IR and1H and13C NMR spectral data for solid C60H36 with the theoretical calculations suggests that the fullerene hydride has aT-symmetric structure and contains four isolated benzenoid rings located at tetrahedral positions on the surface of the closed skeleton of the molecule.

27 citations


Journal ArticleDOI
TL;DR: In this article, it was shown that the low selectivity of the reaction is played by the attack of highly reactive radical particles on the C−H bond of the alkane molecule.
Abstract: n-Heptane is readily oxidized in acetonitrile under the action of H2O2 with a “vanadate anion-pyrazine-2-carboxylic acid” system as the catalyst in air to form isomeric heptyl hydroperoxides (detected by GLC) along with isomeric heptanols and heptanones. Heptyl hydroperoxides slowly decompose at low temperature yielding the corresponding alcohols and ketones (aldehyde). The values of the parameter of the relative normalized reactivity of the H atoms at the carbon atoms in positions 1, 2, 3 and 4 depend on the reaction time and concentrations of the reagents. The value of the parameter of selectivity C(1)∶C(2)∶C(3)∶ C(4) varies in the range from 1.0∶2.8∶2.9∶1.8 to 1.0∶5.6∶5.9∶5.3 The low selectivity of the reaction shows that the key role is played by the attack of highly reactive radical particles on the C−H bond of the alkane molecule.

26 citations


Journal ArticleDOI
TL;DR: In this paper, reaction of [Ph4B]Na and ArB(OH)2 with aryl halides are effectively catalyzed by heterogeneous palladium catalysts (PdCl2C, Pd(0)/C, and palladium black) to give cross-coupling products in high yields.
Abstract: Reactions of [Ph4B]Na and ArB(OH)2 with aryl halides are effectively catalyzed by heterogeneous palladium catalysts (PdCl2C, Pd(0)/C, and palladium black) to give cross-coupling products in high yields.

26 citations


Journal ArticleDOI
TL;DR: The reverse stereocontrol occurs for intramolecular cyclopropanation of allylic and homoallytic diazoacetates and diazosacetamides, and is explained by conformational control of carbonyl alignment (syn oranti to the metal) of the metal carbene intermediate.
Abstract: Diazo ketones with γ or δ double bonds undergo catalytic intramolecular cyclopropanation. These reactions occur with high enantiocontrol when catalyzed by copper semicorrins and bis-oxazolines, but low enantiocontrol characterizes reactions catalyzed by a broad selection of chiral dirhodium(ii) carboxamidates. The reverse stereocontrol occurs for intramolecular cyclopropanation of allylic and homoallytic diazoacetates and diazoacetamides. This divergence is explained by conformational control of carbonyl alignment (syn oranti to the metal) of the metal carbene intermediate.

24 citations


Journal ArticleDOI
TL;DR: In this paper, the complexation of styryl dyes containing the N-phenylaza-15-crown-5 fragment (trans-2a,b) with Ca2+ ions in MeCN was studied.
Abstract: Complexation of styryl dyes containing theN-phenylaza-15-crown-5 fragment (trans-2a,b) with Ca2+ ions in MeCN was studied. Unlike cationic dyetrans-2a, betainetrans-2b forms both complexes of 1∶1 stoichiometry and aggregates consisting of four dye molecules and one Ca2+ ion. Cation-induced aggregation was observed also for the analog of dyetrans-2b, which contains a dimethylamino group instead of an azacrown ether fragment (trans-3). Apparently, the interaction between a metal cation and sulfo groups of moleculestrans-2b ortrans-3 makes the main contribution to the stability of aggregates. The dependence of the stability of aggregates on the nature of the metal cation was studied.

22 citations



Journal ArticleDOI
TL;DR: In this paper, natural (+)-iridomyrmecin and its unnatural enantiomer (−)-IRMecin were synthesized by intramolecular [3+2] dipolar cycloaddition of silyl nitronates that had been generated from the nitro derivatives of (+)- and (−)-citronellenes, respectively.
Abstract: Natural (+)-iridomyrmecin and its unnatural enantiomer (−)-iridomyrmecin were synthesized by intramolecular [3+2] dipolar cycloaddition of silyl nitronates that had been generated from the nitro derivatives of (+)- and (−)-citronellenes, respectively.

Journal ArticleDOI
TL;DR: In this article, an efficient three-step synthesis of [2.2]paracyclophane-pseudo-ortho-dicarboxylic acid by dibromination was developed.
Abstract: An efficient three-step synthesis of [2.2]paracyclophane-pseudo-ortho-dicarboxylic acid by dibromination of [2.2]paracyclophane, thermal isomerization of the resultingpseudopara-dibromide topseudo-ortho-isomer, followed by lithiation/carboxylation was developed. The possibility of preparation of two other novelpseudo-ortho-disubstituted carbonyl derivatives, 4-carboxy-12-(1-oxopenthyl)-[2.2]paracyclophane and di(4-carboxy[2.2]paracyclophanyl-12)ketone, was demonstrated when an excess of lithiation reagent (4 or 10 eq.) was used in the final step.

Journal ArticleDOI
TL;DR: In this paper, the IR spectra of α-azidopolynitroalkanes with NaN3 were studied. And the reaction of 1,1,1-trinitroethane with 1,2,3-triazole, together with 1-azido-1, 1-dinitro-ethane was shown to yield 1, 2,3,3 triazole.
Abstract: Methods for the preparation of α-azidopolynitroalkanes by reactions of polynitroalkanes or α-(difluoroamino)polynitroalkanes with NaN3 were developed. In the case of tetranitromethane, one or two nitro groups can be substituted, depending on the reaction conditions. The reaction of 1,1,1-trinitroethane with NaN3 affords nitro-1,2,3-triazole, together with 1-azido-1,1-dinitroethane. The IR spectra of α-azidopolynitroalkanes were studied.

Journal ArticleDOI
TL;DR: Asymmetric synthesis of β-N-substituted (S)-α,β-diamino acids was accomplished by Michael addition of amines to the NiII complex of the Schiff base derived from (S]-2-[N-(N′-benzylprolyl)amino]benzophenone (BPB) and dehydroalamine as mentioned in this paper.
Abstract: Asymmetric synthesis of β-N-substituted (S)-α,β-diamino acids was accomplished by Michael addition of amines to the NiII complex of the Schiff base derived from (S)-2-[N-(N′-benzylprolyl)amino]benzophenone (BPB) and dehydroalamine. Diastereoselectivity of the reaction is kinetically and thermodynamically controlled. The chiral auxiliary reagent, BPB, can be recovered and reused.

Journal ArticleDOI
TL;DR: In this paper, the degree of association of alanine, serine, arginine, and alanylalanine derivatives of fullerene increases both in acidic and in alkaline media compared to the initial aqueous solution.
Abstract: The dependences of the degree of association of water-soluble amino acid and peptide derivatives of fullerene[60] on pH and the ionic strength of a solution were studied by the diffusion method. The degree of association of alanine, serine, arginine, and alanylalanine derivatives of fullerene increases both in acidic and in alkaline media compared to the initial aqueous solution. Using arginine and alanylalanine derivatives of fullerene as an example, it was demonstrated that the degree of association also increases as the ionic strength of a solution increases.

Journal ArticleDOI
TL;DR: In this article, the dependence of the yield of di(methyl-NON-azoxy)formal on the reaction conditions and the nature of the cation was studied.
Abstract: A series of di(NON-azoxy)formals and some relatedN-alkyl-N′-alkoxydiazeneN-oxides were prepared by the reaction ofN-nitrosohydroxylamine salts with dihaloalkanes. The dependence of the yield of di(methyl-NON-azoxy)formal on the reaction conditions and the nature of the cation was studied. The structure of di(methyl-NON-azoxy)formal and di(phenyl-NON-azoxy) formal as well as of the coppertert-butylnitrosohydroxylaminate was established by X-ray diffraction analysis.

Journal ArticleDOI
TL;DR: In this paper, the optical absorption spectra of spherical particles of silver with a radius (r) of 10 to 80 nm in water were performed. And the results were in good agreement with the optical characteristics of colloidal solutions of silver obtained upon radiochemical reduction of Ag+ ions in aqueous solution.
Abstract: Calculations of the optical absorption spectra of spherical particles of silver with a radius (r) of 10 to 80 nm in water were performed. The single intense absorption band for small particles (r=10 nm) with a maximum at about 395 nm is gradually broadened and shifted to the long-wave region with an increase in the particle size (to 435 nm atr=40 nm). In the case of large particles, the band splits into several components absorbing light in the visible spectral region. The results are in good agreement with the optical characteristics of colloidal solutions of silver obtained upon radiochemical reduction of Ag+ ions in aqueous solution.

Journal ArticleDOI
TL;DR: In this article, the molecular structure of 2,2′-dimethyl-5,5′-di-tert-butylbiphenyl-3,4,3′,4′-diquinone was established by X-ray structural analysis and was characterized by orthogonal (the torsion angle is 82.9°) mutual arrangement ofo-benzoquinone fragments.
Abstract: New di-o-quinones of the biphenyl series, namely, 2,2′-dialkyl-5,5′-di-tert-butylbiphenyl-3,4,3′,4′-diquinones, were synthesized. Their structures were established by IR and NMR spectroscopy. The molecular structure of 2,2′-dimethyl-5,5′-di-tert-butylbiphenyl-3,4,3′,4′-diquinone was established by X-ray structural analysis. The structure is characterized by orthogonal (the torsion angle is 82.9°) mutual arrangement ofo-benzoquinone fragments. ESR studies demonstrated that chemical reduction of diquinone proceeds in four oneelectron stages to form paramagnetic mono- and trianions as intermediates. Quinopyrocatechols, which are intermediates in the synthesis of di-o-quinones, were isolated and characterized.

Journal ArticleDOI
TL;DR: In this article, the crystal structure of air-stable fullerides was determined and a comparative crystal-chemical analysis of the fullerides under study demonstrated that they are isostructural, described by the general formula (Ph4X)2C60Hal (X=P or As, and Hal=Cl, Br, or I), and crystallize in the triclinic system.
Abstract: New air-stable fullerides, (Ph4P)2C60Hal (Hal=Br or I) and (Ph4As)2C60Cl, were synthesized, and their crystal structure were determined. A comparative crystal-chemical analysis of the fullerides under study demonstrated that they are isostructural, described by the general formula (Ph4X)2C60Hal (X=P or As, and Hal=Cl, Br, or I), and crystallize in the triclinic system. The C60− and Hal− anions occupy special centrosymmetric positions. The (Ph4P)+ and (Ph4As)+ cations occupy general positions. The principal parameters of the molecular structures are reported.

Journal ArticleDOI
TL;DR: In this article, the conformational flexibility and effects of substituents in 2-oxo and 2-thioxo-1,2,3,4-tetrahydropyrimidines were studied by the semi-empirical quantum-chemical AM1 method.
Abstract: The conformational flexibility and effects of the substituents in 2-oxo- and 2-thioxo-1,2,3,4-tetrahydropyrimidines were studied by the semiempirical quantum-chemical AM1 method. The substituents at the double bond have no appreciable effect on the conformational characteristics of the heterocycle. The introduction of substituents to the saturated carbon atom results in the conversion of the tetrahydrocycle to a half-chair conformation and in a substantial decrease in the ring flexibility. The results of calculations are confirmed by the X-ray study of both compounds.

Journal ArticleDOI
TL;DR: In this paper, a new homochiral dimericortho-palladated complex bearing a bulky tert-butyl substituent at the carbon stereocenter was synthesized from optically active N,N-dimethyl-α-tertbutylbenzylamine.
Abstract: A new homochiral dimericortho-palladated complex bearing a bulkytert-butyl substituent at the carbon stereocenter was synthesized from optically activeN,N-dimethyl-α-tert-butylbenzylamine. Regioselective activation of only the aromatic C−H bond was shown to occur during the cyclometallation process proceeding under very mild conditions due to steric effects. Spectral characteristics of mononuclear derivatives of the new dimeric complex indicate that the five-membered palladacycle exists predominantly in one of two possible chiral conformations with the axial position of thetert-butyl substituent.

Journal ArticleDOI
TL;DR: In this article, the authors considered the simplest quantum-chemical models of hydrogen spillover over a graphite-like surface as a proton or radical and used the condensed planar C24H12 molecule as a model surface.
Abstract: The simplest quantum-chemical models of hydrogen spillover over a graphite-like surface as a proton or radical have been considered. The condensed planar C24H12 molecule was used as a model surface. Theab initio calculations of the interaction of hydrogen with the model surface were carried out by the restricted Hartree-Fock (HF) method in the STO-3G and 6-31 G* basis sets. The radical hydrogen can not bind to such a surface, whereas the proton binds to it with an energy release of 186 kcal mol−1. The activation energy of the transfer of the proton between two neighboring carbon atoms (10 kcal mol−1) has been determined. The simplest model of the hydrogen migration as a proton over the model surface can be used for describing the spillover of hydrogen over the graphite surface.

Journal ArticleDOI
TL;DR: The basicity of 1-alkyl-2-trifluoromethylaziridines is two orders of magnitude lower than that of non-fluorinated analogs as discussed by the authors.
Abstract: The basicity of 1-alkyl-2-trifluoromethylaziridines is-two orders of magnitude lower than that of non-fluorinated analogs. Aziridines are stable to H2S and AcOH, but react with AcSH, HCl, HBr, H2SO4, TsOH, and picric acid to give products of ring-opening.

Journal ArticleDOI
TL;DR: In this paper, the conformational flexibility of six-membered 1,4-and 1,2-dihydrocycles has been studied and the effect of the conformability of the rings on physicochemical characteristics of compounds is considered.
Abstract: The conformational flexibility of six-membered 1,4- and 1,2-dihydrocycles caused by a flattened shape of the minimum on the potential energy surface is discussed. The effect of the conformational flexibility of the rings on the physicochemical characteristics of compounds is considered.

Journal ArticleDOI
TL;DR: In this article, the authors surveyed data on the partial synthesis of enantiomerically pure sesquiterpenoids of the drimane group, including valuable biologically active natural compounds, from accessible labdane diterpenoid.
Abstract: Data on the partial synthesis of enantiomerically pure sesquiterpenoids of the drimane group, including valuable biologically active natural compounds, from accessible labdane diterpenoids are surveyed.

Journal ArticleDOI
TL;DR: Asymmetric trimethylsilylcyanation of a number of aromatic and aliphatic aldehydes catalyzed by chiral TiIV complexes preparedin situ from Ti(OPri)4 and (1S)-[N,N′-bis(2′-hydroxy-3′-tert-butylbenzylidene)]-1,2-diaminoalkanes gives products with (S)-absolute configurations as mentioned in this paper.
Abstract: Asymmetric trimethylsilylcyanation of a number of aromatic and aliphatic aldehydes catalyzed by chiral TiIV complexes preparedin situ from Ti(OPri)4 and (1S)-[N,N′-bis(2′-hydroxy-3′-tert-butylbenzylidene)]-1,2-diaminoalkanes gives products with (S)-absolute configurations.

Journal ArticleDOI
TL;DR: In this article, the rate of the thermal decomposition of dinitramide was established by the rates of decomposition for different forms of ditramide as the acidity of the medium increases: first, N(NO2)− anions, then HN( NO2)2 molecules, and finally, protonated H2N(NO 2)2+ cations.
Abstract: Kinetic regularities of thermal decomposition of dinitramide in aqueous and sulfuric acid solutions were studied in a wide temperature range. The rate of the thermal decomposition of dinitramide was established to be determined by the rates of decomposition of different forms of dinitramide as the acidity of the medium increases: first, N(NO2)− anions, then HN(NO2)2 molecules, and finally, protonated H2N(NO2)2+ cations. The temperature dependences of the rate constants of the decomposition of N(NO2)− (kan) and HN(NO2)2 (k′ac) and the equilibrium constant of dissociation of HN(NO2)2 (Ka) were determined:kan=1.7·1017 exp(−20.5·103/T), s−1,k′ac=7.9·1016 exp(−16.1·103/T), s−1, andKa=1.4·10 exp(−2.6·103/T). The temperature dependences of the decomposition rate constant of H2N(NO2)2+ (kd) and the equilibrium constant of the dissociation of H2N(NO2)2+ (Kd) were estimated:kd=1012 exp(−7.9·103/T), s−1 andKd=1.1 exp(6.4·103/T). The kinetic and thermodynamic constants obtained make it possible to calculate the decomposition rate of dinitramide solutions in a wide range of temperatures and acidities of the medium.

Journal ArticleDOI
TL;DR: In this paper, the authors observed that the decomposition of dinitramide metal salts in the solid phase is 10 −103 times faster than that in the melt, and its rate has a sharp peak in the region of eutectics melting with the product (metal nitrate), which is instantly inhibited by water vapor.
Abstract: Unusual regularities are observed for decomposition of dinitramide metal salts in the solid phase: the solid-phase reaction is 10–103 times faster than that in the melt, its rate has a sharp peak in the region of eutectics melting with the decomposition product (metal nitrate), and it is instantly inhibited by water vapor. In the inhibited regime, the rate in the solid phase is lower than that in the liquid phase. No indications of this anomalous behavior are observed for the decomposition of the dinitramide guanidinium salt.

Journal ArticleDOI
TL;DR: In this article, the stability constants of extraligand metallocenyl groups (ferrocenyl, ruthenocenyt, and cymantrenyl) with imidazole have been determined.
Abstract: Recently we have obtained the first representatives of a novel class of porphyrins containing metallocenyl groups (ferrocenyl, ruthenocenyt, and cymantrenyl) in mesopositions. 1-3 A direct bond of the macroheterocycle skeleton to the metallocenyl fragments with their specific geometry and reactivity opens up new possibilities tor obtaining porphyrins and their metal!ocomplexes with useful practical properties. The constants of equilibrium of the formation of the extraligand complexes are important characteristics of porphyrin metallocomplexes, determining their behavior in various processes. In this work, complexes of the Zn 1I ion with tetracymantrenylporphyrin (I) , qtetraferrocenylporphyrin (2), and tetraruthenocenylporphyrin (3) are first described, and the stability constants (Kst) of extraligand metallocomplcxes i a -3a with imidazole (lm) have been determined. Complexes la--3a were obtained by interaction of porphytins 1--3 with zinc acetate or zinc chloride in DMF in 85-90% yield and characterized by tH NMR, electronic and mass spectra (FAB). UV spectra (CHCI3) , Lmax/nm: la -464, 559. 595, and 643; 2a -436, 618. and 673: 3a -438, 599, and 647. JH NMR (200 MHz, CDCI3), 8: la -9.67 (s, 8 H. [I-H): 5.79 (m. 8 H, Cp): 530 (m, 8 H, Cp); 2a -9.84 (s, 8 H, 13-H): 5 37 (m, 8 H, Cp): 4.30 (m, 8 H, Cp): 4.07 (s, 20 H, Co); 3a -9.79 (s. 8 H. ~-H): 5.71 (m, 8 H, Cp): 5.05 (m, 8 H, Cp): 4.40 (s. 20 H, Cp). MS (FAB), re~z:., la -1181 [M+HI+; 2a -1108 [M-l; 3a -1292 [M*]. Samples l a 3 a used for determination of K a were additionally purified by column chromatography on A120 3 (Brockmann II activity, benzene), reprecipitated from saturated solutions in benzene or chloroform with cooled hexane, and dried in vacuo. The /(st values for the extraligand complexes of compounds l a -3a with Im and that for zinc tetraphenylporphyrinate (4) (taken as the standard) were obtained by the method of spectrometric titration in benzene at two wavelengths and at 25 ~ on a Specord UV-VIS instrument. The formation of extracomplexes (EC) is accompanied by a bathochromic shift of all absorption bands of the porphyrin chromophore and by a change in their relative intensities. As the metatlocomplex (MC) : l m ratio changes in the range from 1 : 0.1 to 1 : 500, several isobestic points are observed in the spectra of the mixtures. They are indicative of the formation of monoligand EC in the solution and existence of an equilibrium of the type: