Investigation of the lability of the conformations of some alkaloids of the quinolizidine series

Summary The IR and NMR spectra of lupinine, epilupinine, and a series of other alkaloids of the quinolizidine series have been studied.It has been shown that the inhibition of the inversion processes in the molecules of the alkaloids in the solid phase is revealed in a change in the nature of the absorption in the 500–1200 cm^2–1 region.V. I. Lenin Tashkent State University. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 49–54, January, 1971.     

Investigation of the products of the ozonolysis of larixol

On the ozonization of larixol in methanol followed by treatment with ammonium chloride, the main reaction products were 15,16,20-trisnorlabd-6-ene-8,13-dione and 6-hydroxy-8,13;8,14-diepoxy-15,20-bisnorlabd-14-one. When ozonization was performed in methanol in the presence of dimethyl sulfide or in methylene chloride in the presence of pyridine, 6,14-dihydroxy-8,13;8,14-diepoxy-15,20-bisnorlabdane and 6-hydroxy-14,50,20-trisnorlabd-8,13-dione predominated in the reaction products.Institute of Chemistry of the MSSR Academy of Sciences, Kishinev, and Institute of Organic Chemistry of the Bashkir Branch of the USSR Academy of Sciences, Ufa. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 577–584, September–October, 1986.     

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.     

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.     

Investigation of the products of the ozonolysis of larixol

On the ozonization of larixol in methanol followed by treatment with ammonium chloride, the main reaction products were 15,16,20-trisnorlabd-6-ene-8,13-dione and 6-hydroxy-8,13;8,14-diepoxy-15,20-bisnorlabd-14-one. When ozonization was performed in methanol in the presence of dimethyl sulfide or in methylene chloride in the presence of pyridine, 6,14-dihydroxy-8,13;8,14-diepoxy-15,20-bisnorlabdane and 6-hydroxy-14,50,20-trisnorlabd-8,13-dione predominated in the reaction products.     

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.     

Structure of the products of the photoreaction of osthole

The results are given of a study of the photoreaction of osthole in chloroform and acetophenone. It has been shown that when it is irradiated in the latter solvent the cyclization characteristic for coumarins takes place at the double bonds both in the 3,4- position of the coumarin ring and in the side chain, leading to the formation of cyclobutane structures.Leningrad Sanitary-Hygienic Medical Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 165–168, March–April, 1980.     

青海湖区河谷灌丛主要植物微量元素含量特征

采集青海湖地区沙柳河河谷灌丛14种主要植物，采用AAS分析了其中7种微量元素含量。结果表明，元素Cu、Mn、Co含量有较大的植物种问差异，7种微量元素中Se含量最小，Fe含量最大。元素Mn和Fe、Co、Ni之间都具有极显著的正相关性，即相互之间具有协同性作用。     

Effect of the addition of alkanols of different topology to dipalmitoyl-phosphatidylcholine vesicles in the presence of gramicidin

In the present work, we analyze the effect of incorporation of the nonanol family (e.g., 1-Nonanol (1-N), 5-Nonanol (5-N), and 2,6-Dimethyl-4-Heptanol (2,6-DH)) into DPPC LUVs in the presence of different gramicidin concentrations. The principal aim of this work is to study the effect of alkanols solubilization on the physicochemical properties of lipid bilayers in the presence of peptide trans-membrane channels, that is, the effects of nonanol family in the interface of lipid-peptide region, considering that the study provides the analysis of a ternary system by direct excitation as well as by Fluorescence Resonance Energy Transfer. Fluorescence measurements were carried out at 20°C after direct excitation of the extrinsic probe or by Fluorescence Resonance Energy Transfer (FRET) from the tryptophan group of gramicidin. Alkanol incorporation decreases with increasing gramicidin content and branching of the additives. 1-N generates most important changes in the inner part of the bilayer, where it produces an increase in bulk acyl chain mobility. Similarly, 1-N significantly modifies the properties of the hydrophilic-hydrophobic interface region sensed by Laurdan, increasing the polarity of the probe microenvironment and/or increasing the relaxation time of interfacial water molecules. On the other hand, 1-N produces a decrease in PDA fluorescence lifetime, a result that can be explained by a significant amount of water entrance to the inner part of the bilayer. The same behavior was observed when pseudo-first-order quenching rate constants by oxygen were measured. 1-N produces an increase in mobility/solubility of the oxygen in the lipid membrane, an effect that is more noticeable in the deep region of the bilayer sensed by PDA, in the absence and in the presence of 2mol% of Gr. 1-N incorporation produces a greater reduction in GP value than 5-N and 2,6-DH when Laurdan was excited by FRET. These results show that 1-N has the greatest effect in the lipidic domains near the gramicidin channel. On the other hand, excimer-monomer ratios of PDA obtained by FRET show that 1-N reduces the lateral mobility of acyl chains near the lipid-gramicidin interface when gramicidin concentration in the lipid bilayer increases. This effect is more noticeable than that obtained by direct irradiation of the probe in the presence of 5-N and 2,6-DH. On the other hand, the addition of the three alkanols in the presence of Gr produces a noticeable increase in the water permeability, particularly for 1-N. In this context, we propose a scheme that represents the effect of 1-nonanol on the water outflow in DPPC LUVs in the absence and in the presence of Gr.     

Application of neutron activation analysis to the study of the variations of the concentration of trace elements in various organs of rat as a function of age

In order to know the normal distribution of trace elements is rats, in terms of age, we have determined the elemental composition of different organs and body tissues by neutron activation analysis following an animal experiment during which the rats raised outside of any kind of pollution, were fed with a defined diet. The values observed for Co, Zn, Mn, Se, Fe, Cs, Rb, Hg, Cd in heart, body muscles, liver, kidney and testis are represented in table and figures. Except for renal accumulation of Hg and Cd, the more interesting fact revealed in this work, in the accumulation of Fe in body muscles and testis.     

Influence of polarity of medium on formation of intermediates in photolysis of alkylaminobenzophenones in solutions

Flash photolysis has been used in a study of the absorption spectra and decay kinetics of the intermediates in photolysis of 4,4′-bis-dimethylaminobenzophenone, 4,4′-bis-diethylaminobenzophenone, and 4-dimethylamino-benzophenone in various types of solvents. It has been established that flash photolysis of solutions of alkylaminobenzophenones in polar solvents produces not only alkylamine or ketyl radicals, but also an intermediate that absorbs in the 470 nm region, the decay curves of which are described by first-order kinetic equations. In the presence of tertiary amines, the yield of this product is lower. The addition of sodium perchlorate to the solution increases the lifetime of this intermediate species. L. V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of the Ukraine, 31 Nauka Prospect, 252039 Kiev, Ukraine. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 33, No. 1, pp. 27–31, January–February, 1997.     

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).     

13C NMR spectroscopy of the ring-chain tautomerism of the product of reduction of dubinidinone

The existence of ring-chain tautomerism between a cyclic semiketal form and an open-chain -ketol form of the product of the reduction of dubinidinone has been shown unambiguously by¹³C NMR spectroscopy, and this has been confirmed by the results of PMR spectroscopy. It has been shown that in the solution in deuteropyridine and deuterodimethyl sulfoxide the tautomeric equilibrium is shifted in the direction of the formation of the cyclic semiketal, while in trifluoroacetic acid it is shifted in the direction of the open-chain -ketol. Analysis of the IR spectrum has shown that the product of the reduction of dubinidinone exists predominantly in the cyclic semiketal form in the crystalline state.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 100–104, January–February, 1988.     

Study of the properties of pentasil-containing catalysts in reactions of transformation of hydrocarbons 5. Kinetics and mechanism of aromatization of propane and propylene on Ga and H forms of pentasils

The kinetics of transformations of propane and propylene on Ga-modified pentasils and the H-form of zeolite were investigated in a wide range of conversions (20–95%). The selectivity of formation of aromatic hydrocarbons (ArH) on Ga-pentasils is significantly higher than on HTsVM. Quantitative data which demonstrate acceleration of aromatization of propane and propylene in modification of H-TsVM zeolite with gallium were obtained. An especially large increase in the reaction rate is observed in the case of the starting olefin: the rate constants on Ga/HTsVM and HTsVM are respectively equal to 9.21 and 1.44 sec^–1. The significant effect of H₂ on the selectivity of action of the Zn/HTsVM system in aromatization of propane was demonstrated. The effect of H₂ was virtually not manifested on Ga/HTsVM in the conditions studied. The data obtained in the study permitted introducing important corrections in the scheme of the mechanism of aromatization of lower alkanes examined in the literature.For communications 3 and 4, see [1, 10].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1250–1257, June, 1990.     

Evaluation of the uncertainty of environmental measurements of radioactivity

Results obtained by measurement of radioactivity have traditionally been associated with an expression of their uncertainty, based on the so-called counting statistics. This is calculated together with the actual result on the assumption that the number of counts observed has a Poisson distribution with equal mean and variance. Most of the nuclear scientific community has, therefore, assumed that it already complied with the latest ISO 17025 requirements. Counting statistics, however, express only the variability observed among repeated measurements of the same sample under the same counting conditions, which is equivalent to the term repeatability used in quantitative analysis. Many other sources of uncertainty need to be taken into account before a statement of the uncertainty of the actual result can be made. As the first link in the traceability chain calibration is always an important uncertainty component in any kind of measurement. For radioactivity measurements in particular we find that counting geometry assumes the greatest importance, because it is often not possible to measure a standard and a control sample under exactly the same conditions. In the case of large samples we have additional uncertainty components associated with sample heterogeneity and its influence on self-absorption and counting efficiency. In this paper we prepared an uncertainty budget for existing data for ¹³⁷Cs in Danish soil, which is shown to account adequately for all sources of uncertainty. This revised version was published online in July 2006 with corrections to the Cover Date.     

Quantum-chemical study of tautomers of reduced forms of anthraquinone

The quantum-chemical method B3LYP/6-311G(d,p) was used to calculate structural parameters of four conformers of 9,10-dihydroxyanthracene, two conformers of 9-hydroxyanthrone, and the corresponding anions, dianion, and radical anion. The energy of 9,10-dihydroxyanthracene in a gas phase is higher and in aqueous solution lower than the energy of 9-hydroxyanthrone. The dianion can exist exclusively in a polarizable medium.     

Investigation of the influence of pressure on the combustion of Alpagut lignite

This research presents the combustion behavior of lignite under different reaction pressures. Lignite from Alpagut, Çorum of Turkey was combusted in its run off mine (ROM) condition under three different pressure levels of 172, 345, 517 kPa (25, 50, 75 psi). Experiments were done in a fully controlled temperature regime in an isolated combustion tube that operated in coordination with a continuous gas analyzer. Combustion behavior of lignite under different pressures was characterized by effluent gas analysis method. The changes in the amounts of consumed oxygen, evolved carbon oxides as well as variations in the temperature were assessed. The combustion efficiency and effectiveness of lignite was evaluated in terms of thermal features, from the viewpoint of reaction kinetics and by the computation of instantaneous fuel consumption at critical points. It was seen that combustion of lignite tended to turn from a steady profile to a considerably rapid one with increase in pressure, proving to be highly sensitive to the applied pressure level. Also, different levels of pressure resulted in distinctive combustion behavior not only from the view of thermal characteristics, but also in terms of reaction kinetics.     

Effective Methods of Preparation of Some Classes of Phosphororganic Compounds

Abstract

The convenient methods of preparation of secondary and tertiary phosphines, phosphinoxides and phosphonates on the basis of corresponding P-H acids and alkyl-, allyl-, alle-nyl-, ethynylarylhalides, 1,3-diens, acetylenic and vinyl-acetylenic hydrocarbons as alkylating agents have been elaborated. The reactions were proceeded in organic solvents in the presence of potassium carbonate under the conditions of interphase catalysis in liquid-liquid, liquid-solid systems, as well as in superbasic medium (schemes 1, 2)     

Calorimetric determination of the enthalpy of specific interaction of chloroform with a number of proton-acceptor compounds

Calorimetry was used to measure the enthalpies of solution of chloroform in various proton-acceptor solvents and, vice versa, proton-acceptors in chloroform. Based on a previously proposed equation, the enthalpies of specific interaction were calculated and compared with the published data on the enthalpy of hydrogen bonding of chloroform with various proton-acceptor solvents. The composition of the H-bonded complexes mainly formed during the dissolution of proton-acceptor solutes in chloroform was established. It was demonstrated that the dissolution of ethers in chloroform is predominantly accompanied by the formation of 1: 1 complexes, while the dissolution of acetone, dimethylformamide, and dimethyl sulfoxide in chloroform gives rise to more complex associates.