Showing papers in "Russian Chemical Bulletin in 1990"
TL;DR: In this article, a review of mechanochemistry and mechanical activation of solids is presented, and the most urgent problems which concern this field are discussed and discussed. But this review is limited to solids.
Abstract: The paper reviews investigations on mechanochemistry and mechanical activation of solids and discusses the most urgent problems which concern this field.
75 citations
TL;DR: In this paper, a thermodynamic study on urea and 12 of its alkyl derivatives by the methods of combustion calorimetry, vapor formation, and differential scanning was carried out, which permitted determination of the enthalpy of formation of the above substances under standard conditions and in the gas phase.
Abstract: A thermodynamic study was carried out on urea and 12 of its alkyl derivatives by the methods of combustion calorimetry, vapor formation, and differential scanning calorimetry. The numerical data obtained permitted determination of the enthalpy of formation of the above substances under standard conditions and in the gas phase. An additive scheme was proposed for calculating the thermodynamic properties of alkyl substituted urea.
39 citations
TL;DR: In this article, the structures of the N-acetonylazoles were established by 13C,15N, and 14N high-resolution NMR spectroscopy, and general methods have been worked out for the alkylation of nitroazoles with bromoacetone, bromocacetophenone, and diazoacetone in homogeneous media and by phase-transfer catalysis.
Abstract: General methods have been worked out for the alkylation of nitroazoles with bromoacetone, bromoacetophenone, and diazoacetone in homogeneous media and by phase-transfer catalysis. The structures of the N-acetonylazoles were established by13C,15N, and14N high-resolution NMR spectroscopy.
16 citations
TL;DR: In this article, a simple volumetric-gravimetric setup was elaborated and created for determining the equilibrium and kinetic parameters of adsorption in the 1-160 MPa pressure range and the 300-600 K temperature range.
Abstract: A simple precision volumetric-gravimetric setup was elaborated and created for determining the equilibrium and kinetic parameters of adsorption in the 1–160 MPa pressure range and the 300–600 K temperature range. The isotherms of adsorption of nitrogen on crystalline NaA zeolite in the indicated temperature and pressure range were measured. A method was proposed for determining the pore volume of zeolites based on conducting adsorption measurements at high pressures of the gas phase. The isosteric heats of adsorption of nitrogen on NaA zeolite at 305, 334, and 373 K were estimated.
15 citations
TL;DR: A preparative method was developed for the synthesis of 5-fluoro-substituted pyrazoles by the reaction of fluoroolefins with substituted hydrazines in the presence of triethylamine as discussed by the authors.
Abstract: A preparative method was developed for the synthesis of 5-fluoro-substituted pyrazoles by the reaction of fluoroolefins with substituted hydrazines in the presence of triethylamine. The fluorine atom at the C5 position of the pyrazoles obtained is readily substituted by O-, N-, and S-nucleophiles with the formation of 5-alkoxy-, amino-, mercapto-substituted fluoroalkylpyrazoles.
13 citations
TL;DR: In this paper, the authors obtained and characterized acrylamide complexes (AAm) of chlorides and nitrates of Cr(lll), Mn(ll), Fe, Co, Ni, and Zn(ll).
Abstract: We have obtained and characterized acrylamide complexes (AAm) of chlorides and nitrates of Cr(lll), Mn(ll), Fe(lll), Co(ll), Ni(ll), Cu(ll), and Zn(ll). We have shown that all the complexes of chlorides and also nitrates of Fe(lll) and Cu(ll) have the composition MXn'4AAm, while the complexes of Mn(ll), Co(li), Ni(ll), and Zn(ll) contain water of crystallization and are characterized by the composition MXn'4A~m-2H20. All the investigated complexes have an octahedral structure. In the example of the Co(ll) nitrate complex we have established that coordination of the acrylamide occurs at the oxygen atom of the carbonyl group; in this case, the double bond is not touched. However, in the crystal we observe nonequivalence of the double bonds of the acrylamide groups.
13 citations
TL;DR: In this paper, a method was developed for synthesizing 1,2,4-triazolyl-1, 3, 4-oxadiazolyl, 1, 2.4-thiadiazylacetic acid esters based on carbethoxyethylacetimidate chlorohydrate.
Abstract: Preparative methods were developed for synthesizing 1,2,4-triazolyl-1,3,4-oxadiazolyl-, 1,2,4-oxadiazolyl-, and 1,3,4-thiadiazolylacetic acid esters based on carbethoxyethylacetimidate chlorohydrate.
12 citations
TL;DR: In this paper, the charge density transfer from sulfur to boron consisted of about 0.3 e.g., using an intramolecular S → B coordination bond.
Abstract: 1-Butyl-1-dibutylboryl-2-diethylphosphino-2-phenylethene reacts with chloral and oxygen in a manner similar to 1-butyl-1-dibutylboryl-2-dipheylphosphino-2-phenylethene but, unlike the former, can also react with carbon disulfide to form a cyclic complex through an intramolecular S → B coordination bond; charge density transfer from sulfur to boron consisted of about 0.3 e.
12 citations
12 citations
TL;DR: In this article, a controlled condensation of propionaldehyde with Li- or Si-enolates, generated from sec-amyl propionate, readily afforded a mixture of diasteromeric 2-methyl-3-hydroxypentanoic acid 3-pentyl esters, which were easily separated by chromatography.
Abstract: Controlled condensation of propionaldehyde with Li- or Si-enolates, generated from sec-amyl propionate, readily afforded a mixture of diasteromeric 2-methyl-3-hydroxypentanoic acid 3-pentyl esters, which were easily separated by chromatography. The erythro-isomer is the racemic form of the major component (“sitophilate”) of the aggregational pheromone of the grain weevil, a harmful granary pest. Beilis-Hillman condensation of propionaldehyde with sec-amyl acrylate under high pressure and subsequent hydrocuprination or hydrozirconation of the intermediate adduct afforded the (±)-sitophilate in an overall yield of >35%.
10 citations
TL;DR: In this article, the IR spectra of amino alcohols in the gas phase were analyzed and it was shown that they are present mainly as monomers, with or without intramolecular H-bonds (IHB), the former predominating in the vicinal compounds.
Abstract: The IR spectra of aminoalcohols in the gas phase show that in practically all instances (with the exception of N-allylaminoethanol) they are present mainly as monomers, with or without intramolecular H-bonds (IHB), the former predominating in the vicinal compounds. In 1,4-aminoalcohols the concentrations of molecules with and without IHB are practically equalized. The strongest IHB occur in the seven-membered intramolecular rings which are formed in 4-aminobutan-1-o1, for which the greatest difference is observed between the frequencies of the free OH groups and those bound in IHB. Analysis of the effect of an increase in temperature on the intensities of the νOH bands of the free OH groups and of those bound in IHB shows that the partial rupture of the IHB occurs to a greater extent in the unsubstituted aminoalcohols of the vicinal series than in aminoalcohols with two alkyl substituents on the amino group. The IHB exhibit less tendency to break with rise in temperature in the vicinal aminoalcohols than in the 1,3- and 1,4-aminoalcohols.
TL;DR: In this article, a model has been proposed for the hydration of urea, based on the concept of inhomogeneity of the hydrate shell of the urea: stabilization of the structure of water under the influence of carbonyl oxygen and Hcis atoms (positive hydration) and a simultaneous breakdown of water in the region of two Htrans atoms that have approached to a distance of 2.14
Abstract: Measurements have been made of the absorption of EHF radiation (μ 5 cm−1) by aqueous solutions of urea at 20–70°C, over the entire interval of urea solubility. Excess absorption has been found in comparison with the additive magnitude, and this has been attributed to an increase in the fraction of water molecules in the solution with rotational degrees of freedom. A model has been proposed for the hydration of urea, based on the concept of inhomogeneity of the hydrate shell of urea: stabilization of the structure of water under the influence of carbonyl oxygen and Hcis atoms (positive hydration) and a simultaneous breakdown of the structure of water in the region of two Htrans atoms that have approached to a distance of 2.14 » (negative hydration).
TL;DR: The reaction of N-acetyl-2-(cyclohex-1-enyl)aniline with Br2 or N-bromsuccinimide at 20°C is accompanied by intramolecular cyclization to give brominated 3,1-benzoxazines or 4 -acetyl-(3bromo-5-methyl-1,2,3,3a,4,8b-hexahydrocyclopenta[b]indole) as mentioned in this paper.
Abstract: The reaction ofN-acetyl-2-(cyclohex-1-enyl)aniline with Br2 orN-bromsuccinimide at 20°C is accompanied by intramolecular cyclization to give brominated 3,1-benzoxazines or 4-acetyl-(3-bromo-5-methyl-1,2,3,3a,4,8b-hexahydrocyclopenta[b]indole.
TL;DR: In this paper, a kinetic model of the oxidation of hydrogen sulfide was proposed, which contains 201 elementary stages, 23 particles, and satisfactorily describes the experimental data in a wide range of temperatures and pressures.
Abstract: A kinetic model of oxidation of hydrogen sulfide is proposed. The model contains 201 elementary stages, 23 particles, and satisfactorily describes the experimental data in a wide range of temperatures and pressures.
TL;DR: In this paper, 1,3,3-trimethyl-3,4-dihydroisoquinolines, which exist in the imine form, undergo C- hydroxyalkylation upon reaction with hexafluoroacetone and esters of trifluoropyruvic acid at the C 1 CH3 group at 20°C.
Abstract: 1,3,3-Trimethyl-3,4-dihydroisoquinolines, which exist in the imine form, undergo C- hydroxyalkylation upon reaction with hexafluoroacetone and esters of trifluoropyruvic acid at the C1 CH3 group at 20°C. The products with the ketoesters are converted upon heating to γ-lactams. Derivatives of 1,3,3-trimethyl-3,4-dihydroisoquinoline substituted at C1 CH3 group and existing in the enamine form, react with esters of trifluoropyruvic acid at 20°C to give exclusively γ-lactams and do not give reaction products with hexafluoroacetone.
TL;DR: A series of 1,8-naphthalenedicarboximide derivatives containing substituents of different steric and electronic nature were studied by X-ray diffraction analysis as discussed by the authors.
Abstract: A series of 1,8-naphthalenedicarboximide derivatives containing substituents of different steric and electronic nature were studied by X-ray diffraction analysis.Ab initio quantumchemical calculations in the HF/3–21G approximation demonstrated the high conformational flexibility of the imide tetrahydro ring in the molecules of these compounds. The electronic nature of the substituents has no effect on the geometry and conformational flexibility of naphthalenedicarboximides due to weak conjugation between the imide and naphthalene fragments in the molecules. However, the steric effects of the bulky substituents noticeably affect the equilibrium geometry of the imide ring by increasing its conformational flexibility.
TL;DR: In this paper, a method was developed for the directed synthesis of macrocyclic phenylene sulfides with four-to-eight polycyclic fragments, by condensation of dihaloaromatic compounds of various types with sodium sulfide or dithiophenate.
Abstract: A method has been developed for the directed synthesis of macrocyclic phenylene sulfides with 4–8 phenylene sulfide fragments, by condensation of dihaloaromatic compounds of various types with sodium sulfide or dithiophenate. A combination of this method with high dilution techniques has afforded pure macrocycles in high yields, and the macrocycle with six phenylene sulfide fragments in yields as high as 73%.
TL;DR: Fluorohalocarbene, generated from CHCl2F using phase transfer catalysis, reacts with indene, cyclopentadiene, and their alkyl derivatives to form 2-fluoronaphthalenes or fluorobenzenes in 9-60% yield as mentioned in this paper.
Abstract: Fluorohalocarbene, generated from CHCl2F using phase transfer catalysis, reacts with indene, cyclopentadiene, and their alkyl derivatives to form 2-fluoronaphthalenes or fluorobenzenes in 9–60% yield. Reactions proceed through formation of unstable fluorochlorocyclopropanes, which rearrange selectively independently of their stereochemical configuration into the corresponding aromatic fluorides with elimination of HCl.
TL;DR: In this article, the properties of acid sites of ZrO2 and SO4/ZrO 2-based systems modified by metal ions were studied by DRIFT spectroscopy using acetonitrile-d3 as a probe molecule.
Abstract: The properties of acid sites of ZrO2 and SO4/ZrO2-based systems modified by metal ions were studied by DRIFT spectroscopy using acetonitrile-d3 as a probe molecule. In the case of ZrO2. CD3CN interacts with the Lewis acid sites (LAS) with moderate strength. Adsorption on the Bronsted acid sites (BAS) is very weak, which indicates the absence of strong BAS on the surface of ZrO2. Modification of the surface by SO4 groups results in the appearance of a new type of BAS that are capable of adsorbing CD3CN in the polycoordinated form,i.e., stronger complexes with the adsorbate. Addition of metal ions (Fe, Ga, Zn, or Co) leads to the formation of a new type of LAS connected with Fe3+, Ga3+, Zn2+, and Co2+ promoter ions.
TL;DR: Gangliosides were isolated from the starfish Evasterias echinosoma and their structures were elucidated by chemical and physicochemical methods.
Abstract: Gangliosides were isolated from the starfishEvasterias echinosoma and their structures were elucidated by chemical and physicochemical methods. Two major gangliosides were found to be disialogangliosides, whose carbohydrate chain is based on the trisaccharide β-N-acylgalactosaminyl-(l→3)-β-galactosyl-(l→4)-β-glucose (acyl is formyl or acetyl), both residue at of 8-O-methyl-N-acetylneuraminic acid being attached to theN-acylgalactosamine residue at positions 3 and 6. The minor components are disialogangliosides with linear carbohydrate chains in which the terminal sialic acid residue is attached to the penultimateN-acetylneuraminic acid residue at positions 4, 8, or 9. The lipid part of the gangliosides consists of sphingenine and unsubstituted fatty acids (mainly, palmitic and stearic acids).
TL;DR: A statistical thermodynamic treatment of adsorption on zeolites assuming quasiindependent sites has been applied to methane adsorbing on the zeolite NaX and the carbon adsorbent PAU-10 from polyvinylidenechloride in the pressure range 0.1-107 Pa and 120-410 K as discussed by the authors.
Abstract: A statistical thermodynamic treatment of adsorption on zeolites assuming quasiindependent sites has been applied to methane adsorption on the zeolite NaX and the carbon adsorbent PAU-10 from polyvinylidenechloride in the pressure range 0.1–107 Pa and 120–410 K. The relation between the isosteric adsorption heats and the magnitude of adsorption at different temperatures was calculated for both adsorption systems. A sharp decrease in these heats was observed at high adsorption values up to and in the supercritical temperature range.
TL;DR: In this paper, it was shown that it is possible to enlarge the four-membered ring in polyfluorobenzocyclobutenes to fivemembered in the presence of SbF5.
Abstract: Taking perfluoro-1,1-dialkylbenzocyclobutenes as examples, it has been shown to be possible to enlarge the four-membered ring in polyfluorobenzocyclobutenes to five-membered in the presence of SbF5, by cleavage of the four-membered ring followed by cyclization of the resulting polyfluorostyrene to the polyfluoroindane, which then undergoes further reactions. Perfluoro-1-methyl-1-ethylbenzocyclobutene isomerizes at 50°C in the presence of SbF5 to perfluoro-α,β-o -trimethylstyrene, which is reversibly converted at 130°C into perfluoro-1,2-dimethylindane. Perfluoro-l,l-diethylbenzocyclobutene isomerizes at 130°C in the presence of SbF5 to give perfluoro-α -ethyl-β,o -dimethylstyrene, which at 170°C gives perfluoro-2-methyl-3-ethylindene- and perfluoro-2-methyl-3-ethyl-4,5,6,7-tetrahydroindene. The last two compounds, together with perfluoro-o-dipropylbenzene, are obtained from per fluoro-1,2-diethylbenzocyclobutene-with SbF5 at 170°C. From perfluoro-1-methyl-2-ethylbenzocyclobutene with SbF5 at 95°C there is obtained perfluoro-1-ethylindane, while at 130°C, in addition to the latter compound, there are obtained perfluorinated 1,1-dimethylindane, 1,2-dimethylindane, α,β,o-trimethylstyrene, 2,3-dimethylindene, and 2,3-dimethyl-4,5,6,7-tetrahydroindene.
TL;DR: A mixture of 1(3),2-di-O-acyl-3(1)-O-β-gentiobiosyl glycerols was isolated from a sea isolate of Bacillus pumilus.
Abstract: A mixture of 1(3),2-di-O-acyl-3(1)-O-β-gentiobiosylglycerols was isolated from a sea isolate ofBacillus pumilus. The components of the mixture were structurally characterized by mass spectrometry and1H and13C NMR spectroscopy data for the native compounds and their derivatives. The predominant component contains two C15 acyl groups, while the second component contains C15 and C17 fatty acids. Six minor components differ in residues of fatty acids and/or their combinations.
TL;DR: A ganglioside was isolated from the starfish Linckia laevigata, and its structure was elucidated by chemical methods, mass spectrometry, and enzymatic hydrolysis with neuraminidase as mentioned in this paper.
Abstract: A ganglioside was isolated from the starfishLinckia laevigata, and its structure was elucidated by chemical methods, mass spectrometry, and enzymatic hydrolysis with neuraminidase. The ganglioside is a hematoside containing 8-O-methyl-N-glycolylneuraminic acid, 8-O-Me-Neu5Gc-α2→3-Gal-β1→4-Glc-β1→1-Cer. The lipid part of the ganglioside consists of unsubstituted fatty acids (the major component is palmitic acid) and C18∶1-iso-sphingenine.
TL;DR: Bis(cyclopentadienyl)(tetrahydrofurano)(p-tolyl)lutecium was found to be an efficient catalyst for the hydrosilylation of olefins and ketones as mentioned in this paper.
Abstract: Bis(cyclopentadienyl)(tetrahydrofurano)(p-tolyl)lutecium was found to be an efficient catalyst for the hydrosilylation of olefins and ketones.