Stereochemistry of seven-membered heterocycles 5. The conformation of 1.3-dioxacyclohept-5-enes

1. According, to the results of dipole moment and IR and Raman spectroscopy methods, the butenediol acetal's (I)-(IX) are characterized by a conformational equilibrium of the chair and twist forms determined by the influence of various factors. 2. In the determination of the conformational equilibrium of the 2-alkyl-substituted acetals the influence of the "alkyl" dipole must be taken into account. © 1981 Plenum Publishing Corporation

Hydrogen bonds formed by methyl groups of acetonitrile: Infrared and calorimetric study

Solutions of acetonitrile (I) in tetrachloromethane and deuteratred solvents (S) (benzene, acctonitrile, acetone and dimethylsulphoxide) have been studied by IR absorption spectra. The observed solvent effect on the IR spectrum of I was explained in terms of the existence of complexes with hydrogen bonding of the type NCCH3...solvent (S). The strength of the hydrogen bonding was characterized by enthalpies of specific interactions of I with solvents ΔHI/S int(sp). The values ΔHI/S int(sp) were determined both by IR spectroscopy and calorimetry and were found to be within the range 0.3-1.5 kcal mol-1. © 1993

Corrosion Testing of Prospective Chrome Refractory Materials in Borosilicate Glass Melts

Received: 22 November 2023. Accepted: 19 March 2024. Published online: 27 March 2024.Justification is provided of significant practical relevance of the issue of corrosion and erosion resistance of refractory materials in furnaces with direct electric heating that are used for vitrification of high-level waste. Main promising materials are listed, and an algorithm is given for assessing their resistance to attack of borosilicate glass melts under operating conditions of electric furnaces. Corrosion testing of chrome refractory materials of joint Chinese and Belgian origin has been carried out under static and dynamic conditions in a low-melting borosilicate glass melt and in a borosilicate glass melt containing simulated liquid high-level waste (HLW). A search has been conducted among chrome refractory materials of Chinese and Belgian origin for ones demonstrating the highest glass melt attack resistance with regard to the conditions of HLW solidification. The results of these tests will be considered in the design of removable and small-scale melters when selecting the material for melter lining

Stereochemistry of seven-membered heterocycles. 3. Conformation of 5,6-dichloro-1,3-dioxacyclopent-5-enes and the planar-fragment effect

1. It is shown by dipole-moment measurements and IR and PMR spectroscopy that 2-R-5,6-dichloro-1, 3-dioxacyclohept-5-enes (R=C6H5, p-ClC6H4, p-NO2C6H4 and the corresponding cyclohexanone ketal exist in the flexible form; the 2-t-butyl analog exists in a chair-e-twist equilibrium depending on the polarity of the medium. 2. It is shown that a conformational planar-fragment effect occurs as a result of shielding of the C-Cl and C-H bonds in the chair form. © 1981 Plenum Publishing Corporation

Investigation of Borosilicate Glasses with Simulated HLW Components and Determination of Their Chemical Durability

Received: 25.11.2020. Revised: 02.03.2021. Accepted: 03.03.2021. Available online: 04.03.2021.This article belongs to the PCEE-2020 Special Issue.The paper discusses the current status of the HLW vitrification technology applied at the radiochemical plant of the Mayak PA. Conceptual and technical solutions proposed to develop the technology of vitrification of various types of liquid HLW at the Mayak PA are presented. Compositions of borosilicate glasses with HLW components are described, temperatures of their melting and easy pouring are determined. Chemical durability parameters obtained for the borosilicate glasses are provided

Thermoviscosimetric characteristics of borosilicate glasses with regard to the promising area of low-melting compositions currently being developed for the removable small-scale melter designed by Mayak Production Association

Relevance. The need to obtain experimental data on dependence of thermoviscosimetric properties of the examined borosilicate glasses on temperature, in order to solve the problem of developing a low-melting composition of borosilicate glass for a small-scale melter designed by Mayak Production Association. Aim. To get the most complete characterization of the glasses under study using thermoviscometric measurements. Methods. Mathematical modelling, simplex-lattice design. Results and conclusions. One of the most effective methods of experiment planning, which allows, with a relatively small number of experiments, obtaining a mathematical model reflecting the dependence of the studied property of the mixture on the content of components in it, is the simplex experiment planning method. To simplify the solution of such a task, a group or groups of components are usually distinguished, in which the ratio of the mass fraction of the components does not change. In this article, three groups of components are taken – simulators of high-level radioactive waste, sodium and boron oxides, and glass frit. The authors have identified the most promising area, where the mass fraction of glass frit is from 67.5 to 75%, the mass fraction of sodium and boron is from 25 to 32.5% and the mass fraction of high-level waste components is from 0 to 20%. The paper presents the results of thermoviscometric measurements of 15 melts of low-melting borosilicate glasses of different compositions at temperatures ranging from 700 to 1,200°C. Using simplex-based mathematical models of experiment planning, domains of dependence of thermoviscosimetric characteristics of glass melts on their compositions were created. The authors identified the compositions of glass melts that are found within the viscosity limits determined as allowable for glass melt discharge during operation of the removable small-scale melter of Mayak Production Association design

Low-temperature conductivity of quasi-one-dimensional conductors: Luttinger liquid stabilized by impurities

A new non-Fermi-liquid state of quasi-one-dimensional conductors is suggested in which electronic system exists in a form of collection of bounded Luttinger liquids stabilized by impurities. This state is shown to be stable towards interchain electron hopping at low temperatures. Electronic spectrum of the system contains zero modes and collective excitations of the bounded Luttinger liquids in the segments between impurities. Zero modes give rise to randomly distributed localized electronic levels, and long-range interaction generates the Coulomb gap in the density of states at the Fermi energy. Mechanism of conductivity at low temperatures is phonon-assisted hopping via zero-mode states. At higher voltages the excitations of Luttinger liquid are involved in electron transport, and conductivity obeys power-law dependence on voltage. The results provide a qualitative explanation for recent experimental data for NbSe3 and TaS3 crystals.Comment: 12 pages, 1 figur

Stereochemistry of seven-membered heterocycles 5. The conformation of 1.3-dioxacyclohept-5-enes

1. According, to the results of dipole moment and IR and Raman spectroscopy methods, the butenediol acetal's (I)-(IX) are characterized by a conformational equilibrium of the chair and twist forms determined by the influence of various factors. 2. In the determination of the conformational equilibrium of the 2-alkyl-substituted acetals the influence of the "alkyl" dipole must be taken into account. © 1981 Plenum Publishing Corporation

Stereochemistry of seven-membered heterocycles 5. The conformation of 1.3-dioxacyclohept-5-enes

1. According, to the results of dipole moment and IR and Raman spectroscopy methods, the butenediol acetal's (I)-(IX) are characterized by a conformational equilibrium of the chair and twist forms determined by the influence of various factors. 2. In the determination of the conformational equilibrium of the 2-alkyl-substituted acetals the influence of the "alkyl" dipole must be taken into account. © 1981 Plenum Publishing Corporation

Stereochemistry of seven-membered heterocycles 5. The conformation of 1.3-dioxacyclohept-5-enes

1. According, to the results of dipole moment and IR and Raman spectroscopy methods, the butenediol acetal's (I)-(IX) are characterized by a conformational equilibrium of the chair and twist forms determined by the influence of various factors. 2. In the determination of the conformational equilibrium of the 2-alkyl-substituted acetals the influence of the "alkyl" dipole must be taken into account. © 1981 Plenum Publishing Corporation