Showing papers in "Russian Chemical Bulletin in 1980"
TL;DR: The presence of moderately strong electron acceptor substituents (I, COOCH3) in the 4 position of the pyrazole ring does not exclude the possibility of oxidative iodination in its other positions.
Abstract: 1.
N-Methylpyrazoles, which have both electron-donor and electron-acceptor substituents in the 3 or (and) 5 positions, undergo oxidative iodination by I2-HIO3 mixture. Here the halogen atom can be inserted successively in the 4 position and then in either the free 5 or 3 position.
2.
N-Methylpyrazole-4-carboxylic acids and 4-aldehydes under the conditions of this reaction undergo substitutive iodination and form either the 4-iodo or polyiodo derivatives.
3.
The presence of moderately strong electron-acceptor substituents (I, COOCH3) in the 4 position of the pyrazole ring does not exclude the possibility of oxidative iodination in its other positions. Strong acceptor groups (NO2) in the 4 position prevent the reaction.
15 citations
TL;DR: In this paper, the authors studied the kinetics of autoxidation of the ethylenediamine tetraacetate complex of Fe2+ in neutral and acid media.
Abstract: 1.
By the standing-jet method the authors have studied the kinetics of autoxidation of the ethylenediamine tetraacetate complex of Fe2+ in neutral and acid media. From the kinetic results they infer the formation of an intermediate oxygen complex which interacts either with H+ or with a second Fe2+ ion.
2.
In the system Fe2+-EDTA-O2, in an acid medium O2 is reduced by a radical mechanism via intermediate formation of HO2; in a neutral medium, directly to H2O2.
3.
The authors obtain quantitative estimates of the rate constants of formation and further reactions of the oxygenated complex in the absence of ligands and substrates.
11 citations
TL;DR: The condensation of formylcyclopentadienyltri.carbonylrhenium with 2,4-dinitrophenylhydrazine, aniline, and the acetyl derivatives of cyclopentadiyltricarbonylmanganese, cyclopenta-denyiltric-branchs, and -ferroceneleads to the formation of the corresponding 2, 4-dinero-hydrazones, Schiff bases, and α,β-unsaturated ketones as discussed by the authors.
Abstract: 1.
Formylcyclopentadienyltricarbonylrhenium, cyanocyclopentadienyltricarbonylrhenium, and cyanocyclopentadienyltricarbonylmanganese were synthesized.
2.
Formylcyclopentadienyltricarbonylrhenium is reduced by LiAlH4, to hydroxymethylcyclopentadienyltricarbonylrhenium. The condensation of formylcyclopentadienyltri.carbonylrhenium with 2,4-dinitrophenylhydrazine, aniline, and the acetyl derivatives of cyclopentadienyltricarbonylmanganese, cyclopentadienyltricarbonylrhenium, and -ferroceneleads to the formation of the corresponding 2,4-dinitrophenylhydrazones, Schiff bases, and α,β-unsaturated ketones.
10 citations
TL;DR: In this article, a linear correlation between the values of pKa of o-aminomethylphenols and benzylamines in water, ethanol, nitromethane, or acetonitrile, linear correlations are obtained with slopes close to unity.
Abstract: 1.
The basicity of o-aminomethylphenols in nitromethane, acetonitrile, and ethanol is lower in comparison with benzylamines, which do not have any intramolecular hydrogen bonds.
2.
The influence of the intramolecular hydrogen bond on the basicity of the o-aminomethylphenols increases in the following series of solvents: ethanol
6 citations
TL;DR: In this paper, the rate constant of the chain-initiation reaction was determined in the process of branching-chain decomposition of NCl3 on various surfaces, and the stoichiometry of the branching stage was determined.
Abstract: 1.
By the method of ignition delay, the rate constant of the chain-initiation reaction is determined in the process of branching-chain decomposition of NCl3 on various surfaces. Chain initiation is a heterogeneous process.
2.
The rate constant of the reaction Cl + NCl3 — NCl2 + Cl2 is measured.
3.
The stoichiometry of the branching stage is determined. When an NCl2 radical reacts with an NCl3 molecule, three chlorine atoms are formed.
6 citations
TL;DR: In this article, the standard enthalpies of combustion of 14 furan derivatives (including 11 α-nitro-substituted derivatives) were determined by a semimicro calorimetric method for the first time.
Abstract: 1.
The standard enthalpies of combustion of 14 furan derivatives (including 11 α-nitro-substituted furan derivatives) were determined by a semimicro calorimetric method for the first time.
2.
The standard enthalpies of vaporization of nine furan derivatives were determined by the Knudsen effusion method.
3.
The standard enthalpies of formation of the investigated substances were determined in the condensed and gaseous states.
6 citations
TL;DR: The spectral properties of 3,6-di-tert-butyl-4,5-dimethoxy-2-hydroxyphenoxy compounds were investigated in this paper.
Abstract: 1.
When 3,6-di-tert-butyl-o-benzoquinone reacts with sodium alkoxide, it is converted to the anion radical 3,6-di-tert-butyl-4-alkoxy-o-benzosemiquinone and it is converted to its mono- and dimethoxy derivatives by methanol in the presence of manganese diacetate.
2.
In 4-alkoxy-substituted 3,6-di-tert-butyl-2-hydroxyphenoxy compounds, no hydrogen bonding is observed as a result of energetic nonequivalence of their tautomers.
3.
In EPR spectra of 3,6-di-tert-butyl-4,5-dimethoxy-2-hydroxyphenoxy compounds, spectral indications reveal only a rapid exchange (migration of a hydrogen atom between oxygen atoms), which seems to be the result of the small distance between the exchange lines.
5 citations
TL;DR: In this paper, a convenient method was proposed for obtaining ethylα-aminobenzylphenylphosphinate from hydrobenzamide and ethyl phenylphophosphinate, and the absolute configurations of the asymmetric C and P atoms were determined.
Abstract: 1.
A convenient method was proposed for obtaining ethylα-aminobenzylphenylphosphinate from hydrobenzamide and ethyl phenylphosphinate. It was found that this reaction is stereo-specific as regards the configuration of the C and P atoms.
2.
The first members ofα-aminophosphinic acids, and specificallyα-aminobenzylphenyl-phosphinic acid and its ethyl ester, were obtained in the optically active form, and the absolute configurations of the asymmetric C and P atoms were determined.
3.
The rate of hydrolyzing ethylα-aminobenzylphenylphosphinate by dry HBr was studied, 4. Sorbents of the polystyrene type, containing the groupings of R-α-aminobenzyl-phenylphosphinic acid and its ethyl ester, were obtained for the first time.
5 citations
TL;DR: In this article, a method for the preparation of chloromethylphosphine oxides by substitution of the acetoxy group in acetoxymethylphosphines by chlorine using gaseous HC1 at 180-200°C was developed.
Abstract: 1.
We have developed a method for the preparation of chloromethylphosphine oxides by substitution of the acetoxy group in acetoxymethylphosphine oxides by chlorine using gaseous HC1 at 180–200°C.
2.
We have prepared methylbis(chloromethyl)phosphine oxide by reaction of gaseous HC1 with tris(acetoxymethyl)phosphine or tetrakis(hydroxymethyl)phosphonium chloride. In the same way we synthesized dimethylchloromethylphosphine oxide from tris(hydroxymethyl)phosphine methylsulfate.
5 citations
TL;DR: The catalytic activity of PdCl2 in the synthesis of aromatic diisocyanates by carbonylation of dinitro compounds depends on the presence of an organic base (pyridine) and a transition-metal oxide in the reaction system, and on the temperature and pressure as discussed by the authors.
Abstract: 1.
The catalytic activity of PdCl2 in the synthesis of aromatic diisocyanates by carbonylation of dinitro compounds depends on the presence of an organic base (pyridine) and a transition-metal oxide in the reaction system, and on the temperature and pressure.
2.
The oxides V2O5 and MoO3 activate the PdCl2-pyridine catalyst, the oxides of Sc, Cr, Mn, and Ni reduce the yield of diisocyanates, and Co3O4, and CuO inhibit their formation.
3.
The yield of aromatic diisocyanates in the presence of Pd catalysts increases with increasing CO pressure and passes through a maximum at 190–200°C.
5 citations
TL;DR: The NH4+ ion is oxidized by equilibrial N2O5 or the products of its dissociation, NO2+ and NO3−, and the decomposition products of HNO3 as mentioned in this paper.
Abstract: 1.
Within a wide concentration range of HNO3 solutions and mixtures of sulfuric and nitric acids, the velocity of oxidation of NH4+ is proportional to the N2O5 concentration.
2.
The NH4+ ion is oxidized by equilibrial N2O5 or the products of its dissociation, NO2+ and NO3−, and the decomposition products of HNO3.
3.
There is a range of temperatures and NH4+ concentrations in which the oxidation velocity is higher than the velocity of decomposition of the corresponding acid.
TL;DR: In this article, the influence of medium, the concentration, and intensity of irradiation on the quantum yield of the photolysis of 2-amino-1,4-naphthoquinone derivatives has been investigated.
Abstract: 1.
The influence of the medium, the concentration, and intensity of irradiation on the quantum yield of the photolysis of 2-amino-1,4-naphthoquinone derivatives has been investigated. The process under consideration is a one-quantum and monomolecular process the reactive state of which is of thelaπ✶ type.
2.
A quantum calculation has been made of the spectra and electron-density derivatives and the products of their photolysis, and satisfactory agreement with the experimental spectra has been obtained. The lowest excited states of the compounds investigated are singlet and triplet states of thelaπ✶ type.
3.
The influence of the solvent on the position of the maximum of the long-wave band of thelaπ✶ type in the absorption spectra of the 2-amino-1,4-naphthoquinone derivatives have been investigated. The main influence on the spectrum is exerted by the dielectric prpoerties of the medium and by a O...H hydrogen bond.
4.
Satisfactory agreement has been shown of the experimental and theoretical values for the shifts of the luminescence spectra of the photolysis products.
TL;DR: A series of organosilicon peroxides R1O(SiMe2O)nSiMe 2OOR2 and (R3Me2SiO)mSiMe3−m-OOCMe3 were synthesized by reactions of the corresponding chlorosiloxane with tert-butyl or cumyl hydroperoxide in the presence of pyridine as mentioned in this paper.
Abstract: 1.
A series of organosilicon peroxides R1O(SiMe2O)nSiMe2OOR2 and (R3Me2SiO)mSiMe3−m-OOCMe3, where R1=Me3C, Me3Si, or Ph; R2=Me3C, Me2PhC; R3=Me, Ph; n=0, 1, 2; and m=1, 2, 3, were synthesized by reactions of the corresponding chlorosiloxane with tert-butyl or cumyl hydroperoxide in the presence of pyridine.
2.
Siloxane peroxides are effective initiators of the copolymerization of oligoorganovinylsiloxanes and methyl acrylate.
3.
The copolymer formed is more thermally stable than samples obtained in the presence of tert-butyl or dicumyl peroxide.
TL;DR: In this paper, the ionization constants of 3-hydroxypyridine, N-oxide, β-hydrocycled polycyclic carboxylic acids, and their esters were determined by NMR spectroscopy.
Abstract: 1.
The ionization constants of 3-hydroxypyridine, 3-hydroxypyridine N-oxide, β-hydroxypyridinecarboxylic acids, and their ethyl esters were determined by NMR spectroscopy.
2.
The effect of the OH, COOH, COOEt, and NO groups on the chemical shifts and ionization constants was examined.
TL;DR: In this paper, the rate constants of these reactions have been measured and attributed to the oxidation-reduction properties of the peroxide radicals of the amine, and the stoichiometric inhibition coefficients (f) for salts of transition metals, stable nitroxide radicals, aromatic amines, and other antioxidants are attributed.
Abstract: Conclusions1.In the liquid phase N-methylpiperidine is oxidized by O2 according to a radical chain mechanism, which includes a chain-propagating reaction and a quadratic chain-terminating step. The rate constants of these reactions have been measured. A ring methylene group is predominantly oxidized in the molecule of the amine.2.The inhibited oxidation of the amine proceeds with multiple termination of peroxide radicals on one antioxidant molecule. The large values of the stoichiometric inhibition coefficients (f) for salts of transition metals, stable nitroxide radicals, aromatic amines, and other antioxidants are attributed to the oxidation-reduction properties of the peroxide radicals of the amine. The inhibition rate constants and the values of f at 50°C have been measured.
TL;DR: The rate of 1,3-pentadiene hydrogenation is higher when hydrogen feed is by diffusion through the membrane catalyst than when the hydrogen is fed as part of a mixture with the hydrocarbon vapors.
Abstract: 1.
Isoprene and 1,3-pentadiene can be hydrogenated to olefins, without paraffin formation, on a palladium alloy containing 9.8% ruthenium.
2.
The rate of 1,3-pentadiene hydrogenation is higher when hydrogen feed is by diffusion through the membrane catalyst than when the hydrogen is fed as part of a mixture with the hydrocarbon vapors. With the partial pressures of hydrogen and 1,3-pentadiene each greater than unity, the principal hydrogenation product is cis-2-pentene, with mixture hydrogen feed, and 1-pentene, with hydrogen feed through the membrane catalyst.
3.
Although the rate of isoprene hydrogenation also increases as one passes from mixture to diffusion hydrogen feed, the effect is not as pronounced as in the 1,3-pentadiene hydrogenation.
TL;DR: In this paper, the IR and UV spectra of dipyridyl N-oxides have been obtained and the frequencies of the stretching and deformation vibrations of the C-C, C=N, C-H, and \(\mathop N\limits^ \oplus - \mathop O\limit^ \ominus \) groups have been determined and it has been shown that in these compounds two and three π-π* transition systems are observed.
Abstract: 1.
The IR and UV spectra of the dipyridyl N-oxides have been obtained. The frequencies of the stretching and deformation vibrations of the C-C, C=N, C-H, and\(\mathop N\limits^ \oplus - \mathop O\limits^ \ominus \) groups have been determined and it has been shown that in these compounds two and three π-π* transition systems are observed.
2.
The effect of the state of the nitrogen atom and\(\mathop N\limits^ \oplus - \mathop O\limits^ \ominus \) group in a series of isomeric compounds on the structural and electronic characteristics of the heteroaromatic N-oxides has been analyzed.
TL;DR: The methylated iodide of 1-oxyl-2,2,6, 6,6-tetramethyl-4-(β-dimethylaminoethyl)piperidine, which can be used to study the permeability of biological membranes, has been synthesized.
Abstract: 1.
A paramagnetic model of mescaline, viz., 1-oxyl-2,2,6,6-tetramethyl-4-(β-aminoethyl)piperidine,has been synthesized by two methods: with the use of a trifluoroacetyl protective group or reduction of 1-oxyl-2,2,6, 6-tetramethyl-4-carbamidomethylenepiperidine.
2.
The methylation of the amino group in this radical resulted in a decrease in toxicity and the loss of the psychotomimetic properties.
3.
The methylated iodide of 1-oxyl-2,2,6,6-tetramethyl-4-(β-dimethylaminoethyl)piperidine, which can be used to study the permeability of biological membranes, has been synthesized.
TL;DR: In this paper, the kinetics of the accumulation of photooxidation products of cyclohexane have been studied, and a radical mechanism for their formation has been proposed, and the effective rate constant for the recombination of peroxide radicals and their extinction coefficient have been measured.
Abstract: 1.
The kinetics of the accumulation of the photooxidation products of cyclohexane have studied, and a radical mechanism for their formation has been proposed. The effective rate constant for the recombination of peroxide radicals and their extinction coefficient have been measured.
2.
The contribution of the disproportionation of peroxycyclohexyl radicals to the overall process of the destruction of the peroxide radicals amounts to ∿30%. It has been postulated that one of the main paths for the formation of peroxide radicals other than peroxycyclohexyl radicals is the isomerization of the cyclohexoxy radical with cleavage of the C-C bond.
TL;DR: In this article, the decomposition of tert-butyl peroxide in acetonitrile catalyzed by strong Lewis and Bronsted acids is discussed and the dependence of the rates of total decomposition and of homolysis on the concentrations of SbCl5 and tertbutyl hydroperoxide and the activation energies of these processes have been determined.
Abstract: 1.
Di-tert-butyl peroxide, isobutylene, acetone, and methanol are formed in the SbCl5-catalyzed decomposition of tert-butyl hydroperoxide in acetonitrile solution.
2.
The decomposition takes place both heterolytically and homolytically. The contribution from homolysis is 1–5% of the total decomposition. The dependence of the rates of total decomposition and of homolysis on the concentrations of SbCl5 and tert-butyl hydroperoxide and the activation energies of these processes have been determined.
3.
The mechanism of the decomposition of tert-butyl peroxide in acetonitrile catalyzed by strong Lewis and Bronsted acids is discussed.
TL;DR: In this paper, a method was developed for the synthesis of 2,4,6,8-tetraazabicyclo[3.3.0]-3-octanone-7thiones by reacting the 4,5-dihydroxy- and 4, 5-dimethoxy-2-imidazolidinethiones with substituted ureas.
Abstract: A convenient method was developed for the synthesis of 2,4,6,8-tetraazabicyclo[3.3.0]-3-octanone-7-thiones by reacting the 4,5-dihydroxy- and 4,5-dimethoxy-2-imidazolidinethiones with substituted ureas.
TL;DR: In this paper, the authors measured the energy barriers to conversion of the colorless form of five indolinospiropyrans with different 8′-substituents.
Abstract: 1.
We have measured the energy barriers to conversion of the colorless form of five indolinospiropyrans with different 8′-substituents.
2.
We have measured the dependence of the angle between the oscillators of the electronic transitions of the colored form of the spiropyrans on the donor-acceptor properties of these substituents.
3.
The introduction of substituents into the pyran fragment of the spiropyran molecule controls the pathway for the color reaction and the equilibrium among the stereoisomers of the colored form.
TL;DR: In this paper, the rhodium carbonyl hydride complex RhH(CO) (PPh3)3 is an active catalyst for the synthesis of phenyl isocyanate, the o-, m-, and p-tolyl isocynates, and mesityl isomethane from the corresponding aromatic nitro compounds by carbonylation with CO.
Abstract: 1.
The rhodium carbonyl hydride complex RhH(CO) (PPh3)3 is an active catalyst for the synthesis of phenyl isocyanate, the o-, m-, and p-tolyl isocyanates, and mesityl isocyanate from the corresponding aromatic nitro compounds by carbonylation with CO. The optimum reaction conditions were determined (pressure, temperature, time, substrate/catalyst ratio).
2.
The use of MoCl5 as a cocatalyst increases the conversion of the nitro compound, the yield of the isocyanate, and the selectivity of the process.
3.
Methyl substituents in the o-position activate the nitro group when nitro compounds are carbonylated with CO.
TL;DR: By the action of trialkylboranes on N-alkylbenzamidines, N2-dialkylboryl-N1-ALKYBENZAMIDINE (III) have been synthesized as mentioned in this paper.
Abstract: 1.
By the action of trialkylboranes on N-alkylbenzamidines, N2-dialkylboryl-N1-alkylbenzamidines (III) have been synthesized.
2.
The compounds (III) tend to dimerize, this tendency being more pronounced for the compounds with less highly branched alkyl radicals on the B and N atoms.
3.
By the addition of (III) at a C=N bond of dicyclohexylcarbodiimide, heterocyclic compounds of the chelate type, dialkylboryl[N-(N,N′-dicyclohexylamidino)-N′-alkylbenzamidinates], have been obtained.
TL;DR: According to their vibrational spectra, antimony trialkoxides of formula Sb(OR)3 with R=CH3, C2H5, n-C3H7, and i-C4H9 are associated.
Abstract: 1.
According to their vibrational spectra, antimony trialkoxides of formula Sb(OR)3 with R=CH3, C2H5, n-C3H7, and i-C4H9 are associated; no signs of association are observed for the compounds with R=i-C3H7 and t-C4H9.
2.
The molecules of antimony tri-t-butoxide in the liquid state at 20°C exist in the form of rotational isomers having C1 (Cs) and C3 (C3v) symmetry, with the C1 (Cs) conformer predominating. Upon freezing, the C3 (C3v) conformer remains in the crystal.
TL;DR: The electrophilic alkylation of some fluorinated ethylenes by 1,1,1-trifluoroethane was performed in this paper, which was the first electrophilicity of a fluorinated polyethylene.
Abstract: The electrophilic alkylation of some fluorinated ethylenes by 1,1,1-trifluoroethane was accomplished by us.
TL;DR: In this paper, new chelate compounds of boron were synthesized by adding 2-pyridylaminodiorganylboranes and 2pyrimidinylaminodorodorodorogenylborane to dicyclohexylcarbodiimide.
Abstract: New chelate compounds of boron, in which the chelating agents are, respectively, N.N′-dicyclohexyl-N′'-(2-pyridyl)guanidine and N,N′-dicyclohexyl-N′'-(2-pyrimidinyl)guanidine, have been synthesized by adding 2-pyridylaminodiorganylboranes and 2-pyrimidinylaminodiorganylboranes to dicyclohexylcarbodiimide.
TL;DR: In contrast to alkenylaromatic compounds, 2-alkenylfurans react with ethyl diazoacetate under conditions of catalytic, thermal, and photolytic decomposition of the latter with the addition of the carbethoxycarbene fragment both at the exocyclic double bond and also at the furanyl ring, which in the latter case leads to the formation of esters of triply unsaturated ketoacids with yields up to 58 as mentioned in this paper.
Abstract: 1.
In contrast to alkenylaromatic compounds, 2-alkenylfurans react with ethyl diazoacetate under conditions of catalytic, thermal, and photolytic decomposition of the latter with the addition of the carbethoxycarbene fragment both at the exocyclic double bond and also at the furanyl ring, which in the latter case leads to the formation of esters of triply unsaturated ketoacids with yields up to 58%.
2.
The reaction direction and the yields of the final products depend on the degree and the character of substitution of the vinyl group and position 5 of the furan ring and not on the method of decomposition of ethyl diazoacetate.
3.
Satisfactory correlation between the logarithm of the relative rate constant of the reaction of addition at the vinyl group of 5-substituted 2-vinylfurans and the Hammettσ constants is observed upon the thermocatalytic decomposition of EDA. The value of ρ indicates the great sensitivity of the reaction as regards electron effects of the substituents in comparison with styrenes.
TL;DR: The conformational equilibrium, chair (e)-twist, which is anancomerically shifted toward the chair form for R=C(CH3)3, is characteristic for 2-benz[e]-1,3-dioxepanes, where R=H, CH3, C2H5, n-C3H7, and i-C 3H7 as discussed by the authors.
Abstract: 1.
The conformational equilibrium, chair (e)-twist, which is anancomerically shifted toward the chair form for R=C(CH3)3, is characteristic for 2-benz[e]-1,3-dioxepanes, where R=H, CH3, C2H5, n-C3H7, and i-C3H7.
2.
A correlation between the μ2 of the 2-alkyl-1,3-dioxanes and the induction constants σI was found.
TL;DR: In this article, the photolysis of dihydroquinolines leads to cleavage of the N-H bond and to the formation of RN radicals, which are capable of dimerization, and not to cleaving of the C-N bond and formation of the o-quinone aldine structure.
Abstract: 1.
In solvents with a low electron affinity (hydrocarbons, alcohols) the photolysis of dihydroquinolines leads to cleavage of the N-H bond and to the formation of RN. radicals, which are capable of dimerization, and not to cleavage of the C-N bond and the formation of the o-quinone aldine structure.
2.
The low recombination rate of the RN. radicals is one of the reasons for the greater effectiveness of ethoxyquin as antioxidant.