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.     

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.

     

Heats of formation and kinetics of decomposition of nitroalkanes

Heats of formation of solid, liquid, and gaseous nitroalkanes have been shown mostly to obey group additivity. Group values have been obtained for carbon atoms attached to one, two, and three nitro groups. The heat of formation of 1,1,1,3,5,5,5,-heptanitropentane, either solid or liquid, cannot be fitted to the scheme, even allowing for gauche effects. The differences between observed and estimated values for 1,1,1-fluorodinitroalkanes and 1,2-dinitroethane are larger than expected and should be further investigated. Activation energies have been calculated for decomposition by five-center elimination of HONO from mononitro- and dinitroalkanes using thermochemistry and estimated activation energies for the reverse reactions. The key data for these estimates were previously reported activation energies for the decomposition of nitroethane and 1,2-dinitropropane. The calculations also gave values for the heats of formation (in kcal/mole) of nitroethylene 12.4, and 1-nitropropylene 5.6, and 2-nitropropylene 1.6. Activation energies were calculated for the competing unimolecular reaction, C? N bond fission, from thermochemistry and previously reported activation energies for the decomposition of 1,1- and 2,2-dinitropropane. Comparison of Arrhenius parameters for the two competing processes, namely, HONO and C? N bond fission, shows that, for the geminate dinitroethanes and dinitropropanes, C? N bond fission is faster about 370°K and, for the mononitroalkanes and for all the mononitroalkanes and dinitroalkanes, C? N bond fission is faster above 770°K.     

非那雄胺合成工艺改进

非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。     

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.     

Calculation of enthalpies of hydrogenation of hydrocarbons

Sets of hydrogen molecule equivalents have been developed which permit the calculation of hydrogenation of different types of carbon-carbon bonds from ab initio total energies (3-21G and 6-31G* basis sets, and, to a more limited extent, for MP2/6-31G* data) of reactants and products. The calculated enthalpies of hydrogenation are in good agreement with experiment for unstrained molecules, with average errors on the order of 2 kcal/mol. The 6-31G* equivalents allow the enthalpies for strained molecules to be calculated accurately, but the 3-21G equivalents do not. The equivalents for both basis sets have been tested by calculating the enthalpies of hydrogenation of carbon-carbon bonds in nitrogen- and oxygen-containing organic molecules, free radicals, and classical carbocations. The results are in good agreement with experiment in most cases.     

栽培草莓品种果实香气特性研究

通过对4个不同栽培草莓(Fragaria ananassa Duch．)品种果实糖和氨基酸测定及香气的GC-MS分析,结果表明：不同品种间氨基酸和糖含量不同,氨基酸含量由高到低依次为丰香、瓦尔达、哈达和全明星;哈达、丰香、全明星和瓦尔达4个品种果实分别检测出39、46、37和44种香气成分,各占总峰面积98.52％、99.15％、98.77％和95.4l％,检测成分的多少与氨基酸总量显著正相关,相关系数为0.967;哈达有5种独有的成分,丰香有9种独有的成分,全明星有3种独有的成分,瓦尔达有2种独有的成分,4个品种共有的成分有19种。     

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.     

Adsorption of proteins of the surfaces of modified silicas

Sorbents based on porous and nonporous varieties of silica containing chemisorbed primary amines, alcohols, amino-alcohols, amide groups, and phenyl radicals with different types of substituents in the surface layer have been synthesized. It has been established that, depending on the nature of the modifying layer, electrostatic and hydrophobic interactions make the principal contribution to the adsorption of proteins. The supports obtained may be used for the immobilization and Chromatographic separation of biopolymers.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 23, No. 2, pp. 237–241, March–April, 1987.     

Composition of the phospholipids of seeds of Cercis siliquastrum

The phospholipids of the polar lipids of the seeds of the Judas tree and the fatty-acid composition of the N-acylphosphatidylethanolamines, the phosphatidylcholines, and the phosphatidylethanolamines, and also the molecular-species types of the fatty acids of the phosphatidylcholines and the phosphatidylethanolamines have been studied. It has been established that the seeds of the Judas tree contain ten phospholipids. The main fatty acids are palmitic and oleic.I. V. Kutateladze Institute of Pharmacochemistry, Georgian Academy of Sciences. Translated from Khimiya Prirodnykh Soedinenii, Nos. 3,4, pp. 320–323, May–August, 1992.     

Study of the degradation of polyurethanes. III. Mechanism of the photodegradation of polyurethane

The effect of triplet sensitizers, benzophenone and anthraquinone and metal acetylacetonates [Co(II, III), Cu, Sn, and Ni] on the photodegradation of polyurethane was examined. Ultravioletvisible (UV-V) absorption spectra, gel formation, and luminescence emission of the polymer before and after irradiation were measured. Changes in UV-V absorption of the polymer and the formation of an insoluble fraction in the polymer were accelerated in the presence of the triplet sensitizers, and (Co(II, III)), Cu, and Sn acetylacetonates. Unirradiated polyurethane was excited by irradiation at 290 and 346 nm, and emitted light at 310 and 420 nm. After 1/2 hr irradiation emission of luminescence was observed at 430 nm, excitation at 290 and 346 nm; after 2hr irradiation at 530 nm, excitation at 420 nm was observed. The results suggest that photodegradation of the polyurethane proceeds via excited triplet states forming excimer between the polymers at the initial stage and exciplexes between the polymer and degradation products or intermediates after a certain irradiation.     

Phospholipids of the seeds of two species of Erysimum

Summary The phospholipid complexes of the seeds ofErysimum diffusum andE. sylvestris have been investigated. It has been found that the amount of phospholipids in the seeds ofE. diffusum is lower than in those ofE. sylvestris, but their qualitative compositions are similar. The fatty-acid compositions of the triglycerides and of the total phospholipids of the two plants investigated have been studied. It has been established that the total phospholipids of the species ofErysimum under consideration and individual fractions of them differ by the degree of saturation and the qualitative and quantitative composition of the acids that they contain and, consequently, the phospholipids present in greatest amount differ in their molecular compositions.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 623–627, September–October, 1977.     

化学单元教学设计的探索

论述了单元教学是落实化学新课程三维目标的基本教学过程,同时对教学单元的含义、教学单元的选择与建构、化学单元教学设计及其意义进行了阐述。     

Mechanism of photodecomposition of spiropyrans

Spectrophotometric and ESR measurements have been made in a study of photodecomposition and thermodecomposition reactions of spiropyrans (SPs) of the indoline and oxaindan series of solutions and in the crystalline state, at various temperatures. From an analysis of the experimental data, involving certain concepts developed previously regarding the mechanisms of photochemical reactions of SPs, it has been concluded that the most probable reactions of photodecomposition and thermodecomposition of SPs are -rupture of a bond and the formation of a chemically active biradical, as well as irreversible reactions of SP ion radicals that arise as a consequence of phototransfer and dark transfer of electrons in associates of various species of the SP.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 5, pp. 539–545, September–October, 1989.     

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).     

Mononitration of derivatives of benzisatins

The mononitration of benz[e]-, benz[f]-, and benz[g]isatins and their tetrahydro derivatives was realized. It was established on the basis of an analysis of the ¹H NMR and mass spectra that substitution takes place at position 5 in the derivatives of the [g] series and at the position adjacent to the NH group in derivatives of the [f] series and in the case of 6,7,8,9-tetrahydrobenz [e]isatin. This reaction path corresponds to the maximum electron density in the HOMO, calculated by the CNDO method. In benz[e]isatin, contrary to the general relationship and to the quantum-chemical prediction, the nitro group initially enters the ring annellated with the indole ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 60–65, January, 1989.     

Structure of the products of the metabolism of deoxypeganine and of deoxyvasicinone

The structures of the main components of the total metabolites of the anticholinesterase drug deoxypeganine (DOP) and its analog deoxyvasicinone (DOV) in the rat organism have been studied. The structures of two metabolites of DOP and DOV — 11-hydroxydeoxyvasicinone and 2-(-ethoxycarbonyl)ethyl-4-quinazoline — have been determined by the PMR method. On the basis of their structures and the results of measurements of the elementary compositions of ions, the fragmentation of the compounds has been elucidated. A minor component of the total metabolites has been isolated by chromato-mass spectrometry and for it the structure of 6-methoxydide-hydrovasicinone is proposed. A scheme of the metabolism of DOP and DOV has been put forward.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 758–766, November–December, 1983.     

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.     

Mechanisms of pyrolysis of fluoropolymers

A systematic study of the mechanisms of the pyrolysis of fluoropolymers was made by means of pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) and direct Py-MS. For perfluoropolymers and chlorine-containing fluoropolymers the depolymerization reaction predominates during pyrolysis. However, the introduction of OCF₃ groups into perfluoropolymers in place of F atoms brings about significant changes in their mode of degradation. The OCF₃ groups activate the F atoms attached to the same carbon atoms and make them easier to transfer. Therefore, random chain cleavage accompanied by the F transfer becomes predominant in the course of the pyrolysis. When the F atoms of perfluoropolymers are partly replaced by H atoms, elimination of hydrogen fluoride and chain cleavage accompanied by H transfer would occur with great ease. For fluoropolymers containing H, Cl and OCF₃ as side groups, the depolymerization, the elimination of hydrogen chloride and hydrogen fluoride and the random chain cleavage accompanied by H and F transfer would occur simultaneously and compete with each other.