Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

     

Influence of viscosity of medium on processes of oxygen quenching of excited states of mesoporphyrin

The oxygen quenching rate constants for singlet and triplet excited states of the dimethyl ester of mesoporphyrin IX increase with decreasing viscosity of the medium and reach a maximum at a viscosity of approximately 0.4 mPa·sec, after which the rate constants begin to decrease. The drop in rate constant with increasing fluidity of the medium may be related to a nonequilibrium character of the elementary act in the interaction of the reactants in the solvent cage. In viscous media such as isopropyl alcohol, isobutyl alcohol, and isoamyl alcohol, the reaction radius is greater than the sum of the radii of the reacting particles. The long-range character of these processes is due to the relatively weak dependence of the quenching probability on distance.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 2, pp. 161–167, March–April, 1989.     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

Neutral diterpenoids of oleoresins of five species of conifers of Transcarpathia

The compositions of the neutral diterpenoids of the oleoresins of five species of conifers growing in the Transcarpathia have been studied. It has been found that the oleoresins ofAbies alba M.,Larix decidua M., andPicea excelsa L. contain more than 50% of neutral diterpenoids. The group and qualitative compositions of the oxygen-containing diterpenoids have been determined. In the oleoresins ofAbies alba,Picea excelsa, andPicea abies tertiary alcohols — cis-abienol and isocembrol — predominate, while inLarix decidua the main component is the hydroxy ester larixyl acetate. Primary alcohols related to the resin acids have been found in all the oleoresins investigated. Features of the distribution of diterpenoids according to the species of conifers have been revealed. The results obtained are necessary for the chemotaxonomy of conifers of the family Pinceae.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Khimiya Prirodynkh Soedinenii, No. 6, pp. 812–816, November–December, 1988.     

Direction of epoxidation of esters of polyunsaturated acids

Conclusions The direction of the epoxidation of a number of polyunsaturated acids was studied and it was shown that the epoxidation proceeds at the double bonds furthest away from the carbethoxyl group.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 943–947, April, 1977.     

Summary of development of the theory of stability of colloids and thin films

In this review, the research of the author in the field of colloidal systems is summarized. The factors influencing colloidal stability are systematized and analyzed. Examples are presented to illustrate the practical utilization of the theory of stability of colloids and thin films.This review was prepared on the basis of the works of the author, which were awarded the State Premium for 1991 in the field of science and technology, chemistry section.Institute of Physical Chemistry, Russian Academy of Sciences, 117915 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1708–1717, August, 1992.     

Numerical analysis of the stereoselectivity of photoreduction of cyclohexanones and of its variations. Confirmation of the involvement of a pyramidal radical

A general method of numerical analysis of the experimental data was applied to the study of the stereoselectivity of photoreduction of cyclohexanones. The two assumptions, which were previously, put forward to account for the stereoselectivity variations, namely:

(1) the involvement of a more or less solvated planar radical, (2) the involvement of two diastereoisomeric pyramidal radicals which carry the stereochemical information could thus be separated with a high degree of reliability; the second assumption only is to be retained. The ratio of the spontaneous inversion rates of the two pyramidal radicals could be calculated and compared with the experimental value which was obtained independently from the selective deuteriation of the diastereoisomeric cyclohexanols.     

Milestones of the development of kinetics of electrode reactions

The birth and the development of the kinetics of electrode processes?Cmostly focusing on the case of the hindered charge transfer step and the early period?Care reviewed. It is shown how this important branch of electrochemistry was established and how and why the ideas of chemical kinetics have been introduced in electrochemistry. The history of electrode kinetics represents a good example for the progress of science in general, since it can be followed how the experimental observations conduce to the development of theory and how the theory influences further research. It is also demonstrated that the acceptance of new ideas is a thorny path. An attempt is made to acknowledge the merit of the scientists whose experimental or theoretical contributions brought paradigmatic changes in the thinking about the nature of electrode processes. In this context, the appropriate naming of equations is also discussed by using the example of the Erdey-Grúz?CVolmer vs. Butler?CVolmer equation. A discussion concerning the present trends is also included, which perhaps may predict the near future. A longer prognosis is avoided since the history of science teaches us that the real breakthroughs could not be predicted.     

Microstructural investigations of surfaces of destruction of carbon plastic

Results of endurance tests of microplastic on the basis of carbon fiber and epoxy binding, as well as data of microstructural analysis of the surfaces of destruction, are presented. Based on the obtained results, an attempt was made to classify the main types of damage. The dependence of the mechanism of the destruction process on the deformation properties of bindings was found.     

Determination of degree of crystallinity of drawn polymers by means of density measurements

The well known procedure of determining the degree of crystallinity by means of measuring the density presupposes the knowledge of both the densities ρ_c and ρ_a of the crystalline and of the noncrystalline regions. By combination of small-angle and wide-angle x-ray scattering and of density measurements it can be shown that this method is not justified in the case of drawn polyethylene if the values of ρ_c and ρ_a known from isotropic material are used. Both ρ_c and ρ_a depend considerably on annealing and drawing conditions. In addition the effective density ρ_c^* of the more densely packed phase in a two-phase structure is much lower than the value ρ_c calculated from the positions of the x-ray reflections due to a large number of lattice defects. This conclusion is based on the results of three independent sets of experiments: determination of the mean-square fluctuation of density 〈η²〉 by means of x-ray small-angle scattering; x-ray wide-angle measurements of the positions of the crystal reflections and of the halo arising from the noncrystalline regions; and comparison of densities and long periods of samples treated at various annealing temperatures.     

Synthesis of phenolic components of Grains of Paradise

Two vanilloids, (5E)-8-(4-hydroxy-3-methoxyphenyl)oct-5-en-4-one (1) and 4-[3-hydroxydecyl]-2-methoxyphenol (2), isolated from the dried seeds of Grains of Paradise (Aframomum melegueta), were synthesized; the latter compound was made as the S-enantiomer and the material derived from the seeds was found to be a 1:1.7 mixture of the R and S isomers. The synthetic route used should allow the preparation of analogs having extended alkyl chains and consequently different lipophilicity, and 3, a homolog of 2, was also prepared.     

Optimization of the conditions of acid hydrolysis of tetraethoxysilane and identification of primary products of sol-gel synthesis

The effect of the reactant ratio in the Si(OEt)₄-H₂O-EtOH-HCl system on the hydrolytic polycondensation of tetraethoxysilane and gelation rate was examined. A mass-spectrometric study showed that the primary products of the sol-gel process are linear and cyclic oligosiloxanes containing hydroxy and ethoxy groups at the silicon atoms.     

Neutral diterpenoids of oleoresins of five species of conifers of Transcarpathia

The compositions of the neutral diterpenoids of the oleoresins of five species of conifers growing in the Transcarpathia have been studied. It has been found that the oleoresins ofAbies alba M.,Larix decidua M., andPicea excelsa L. contain more than 50% of neutral diterpenoids. The group and qualitative compositions of the oxygen-containing diterpenoids have been determined. In the oleoresins ofAbies alba,Picea excelsa, andPicea abies tertiary alcohols — cis-abienol and isocembrol — predominate, while inLarix decidua the main component is the hydroxy ester larixyl acetate. Primary alcohols related to the resin acids have been found in all the oleoresins investigated. Features of the distribution of diterpenoids according to the species of conifers have been revealed. The results obtained are necessary for the chemotaxonomy of conifers of the family Pinceae.     

Study of methods of preparation of 1,4-diglycidyltetrazolone. New synthesis of triglycidylisocyanurate

1,4-Digtycidyltetrazolone was synthesized for the first time by the reaction of tetrazolone and epichlorohydrin with subsequent treatment of the products of addition with a base. The basic directions of the reaction of carbamoyl azide with epichlorohydrin, which yields triglycidylisocyanurate and diglycidylcarbamoyl dude, were investigated. The features of the synthesis and properties of the substances obtained were described.     

Phospholipids of the seeds of experimental varieties of kenaf

Phospholipids of the seeds of kenaf of the variety Opytnyi-1931 are similar with respect to their set of components and the qualitative composition of the fatty acids of homogeneous classes to the phospholipids of the variety Opytnyi-1972, but differ with respect to the amounts of individual acids. The fatty-acid composition of the lysophosphatidylcholines and lysophosphatidylinositols of experimental varieties of kenaf seeds have been studied for the first time.Institute of the Chemistry of Plant Substances of the Academy of Sciences of the Uzbekh SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 158–160, March–April, 1986.     

Investigation of thermal decomposition of anthranilates of alkali metals

The thermal properties of the anthranilates of the alkali metals Li, Na, K, Rb and Cs were studied. Thermal, chemical and X-ray analyses and infrared spectroscopy were used to determine the reactions of decomposition of these compounds. The thermal properties of the anthranilates of the alkali metals were compared with those of other metals.This work was done within Project 01.17: New Methods in Analytical Chemistry and Their Application in the National Economy.     

Effect of composition of coordination sphere on value of constant of additional hyperfine structure of EPR spectra

Conclusions Replacing the oxygen atoms by sulfur atoms in the coordination sphere of nitrogen-containing copper complexes leads to a substantial increase in the constant of the additional hyperfine structure from the nitrogen atoms, and consequently also to an increase in the degree of covalency of the Cu-N bonds.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 704–706, March, 1974.The authors thank V. I. Nefedov for taking the x-ray electronic spectra of compounds (I) and (II).     

Effect of the Method of Modification of Zeolite X on Selectivity of Catalytic Methylation of Toluene

Theoretical and Experimental Chemistry - The effect of the method of modification of catalysts based on zeolite X by cesium and magnesium cations (ion exchange and impregnation) on the selectivity...     

Catalytic electroreduction of oxygen on products of pyrolysis of heterobimetallic complexes of zinc

Electrocatalysts for reduction of oxygen were synthesized from AG-3 activated carbon promoted with pyrolized heterobimetallic complexes [CoLCl₂] [ZnDMFACl₃] and [ML][ZnCl₄] (M = Cu²⁺, Ni²⁺; L = 4,6,6-trimethyl-1,9-diamino-3,7-diaza-nona-3-ene). The optimal conditions of synthesis of the catalysts, which affect the efficiency of oxygen electroreduction, were found and the activity series of the catalyst in relation to the nature of the second metal was determined.     

pH电位法研究络合物稳定常数——一种新的数据处理方法的尝试

在水溶液的络合平衡研究中,pH电位法得到广泛应用,但有一定局限性。G·Shwarzenbach提出的pH-pM同时测定法原则上可以处理多级酸式络合常数,但实验受到仪器的限制。借助徐光宪^[4]的络合物吸附平衡理论可以将Y₀(Frouaeus函数)与n_L(生成函数)相联系,从而可能将上述两种方法沟通起来^[2]。但文献[2]所介绍的方法只适于求各级正常络合物常数。