Condensed heterocycles with a thiazole ring. 1. Thiazolo[3,4-a]pyrimidine derivatives

It is shown that the reaction of 1,3-dicarbonyl compounds or their acetals with 2-methylthio-4-amino-5-phenylthiazolium benzenesulfonate gives 6-methylthiothiazolo[3,4-a]pyrimidinium salts, which react with the appropriate intermediates to give polymethine dyes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 634–638, May, 1982.     

N-Substituted trifluoroacetimidoyl halides: synthesis and properties

N-Substituted trifluoroacetimidoyl halides in ionic-type transformations readily undergo nucleophilic substitution and dehydrofluorination rather than 1,3-dehydrohalogenation to give nitrile ylides.     

Magnetocaloric effect and heat capacity of ferrimagnetic nanosystems: Magnetite-based magnetic liquids and suspensions

The magnetocaloric effect (MCE) and heat capacity of magnetite-based magnetic liquids and suspensions of magnetite in cyclohexane and water were studied calorimetrically at various temperatures and magnetic inductions. It was found that the magnetocaloric effect in the systems under study increases nonlinearly with the magnetic induction. In contrast to monocrystalline magnetite, the inverse temperature dependence was observed for the MCE in the nanosystems studied over the entire temperature range covered; i.e., the effect decreases with increasing temperature. It was found that the dependence of the specific heat on the magnetic induction passes through a maximum for all the systems at all temperatures tested; its height increases with the temperature. The extremal character of the dependence can be explained by the formation of chain structures of magnetite nanoparticles in the presence of a magnetic field.     

Mesoionic compounds with a bridged nitrogen atom.

The cyclization of (4-quinazolinylthio)phenylacetic and acetic acids gives extremely reactive thiazolo[3,2-c]quinazolinium 3-oxides, which, depending on the structure of the mesoionic ring, react with either electrophilic or nucleophilic reagents.See [1] for Communication 16.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 408–412, March, 1989.     

The contact angles of surfactant solution on the quartz surface

Summary The contact angles formed on the quartz surface by 0,1 N NaCl aqueous solution at different pH were measured. The effect of surfactants such as anion-active sodium dodecyl sulphate (NaDS) and cation-active cetyltrimethylammonium bromide (CTAB) was investigated. The results are interpreted in terms of the Frumkin-Derjaguin theory of wetting.With 4 figures and 1 table     

Mesoionic compounds with a bridged nitrogen atom. 13. Thiazolopyrimidoindoles

Derivatives of a new heterocyclic system, viz., thiazolo[3,43,2]pyrimido-[4,5-b]indole, are formed when 4-amino-2-methylthio-5-phenylthiazolium benzenesulfonate is heated with 3-formyloxindole in phosphorus oxychloride.See [1] for communication 12.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 502–504, April, 1985.     

Condensed heterocycles with a thiazole nucleus. 8. Thiazolo[4,3-a]pyrimido[5,4-e]pyrimidines

Condensation of 4-amino-2-methylthiothiazolium salts with 2,4,6-trichloro-5-formylpyrimidine or 3-R-2,4-dioxo-6-chloro-5-formyl-1,2,3,4-tetrahydropyrimidines yielded mesoionic derivatives of a new heterocyclic system — thiazolo[3,4-a]pyrimido[5,4-e]-pyrimidine — which can be used for the synthesis of polymethine dyes. The absorption maxima of these dyes are bathochromically shifted by 10–20 nm relative to the maxima of the thiazolopyrimidine analogs. The structure of the compounds synthesized was demonstrated by the PMR and IR spectra.For communication 7, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1126–1128, August, 1984.     

Application of minimization methods in calculating atoms with several open shells

Basing on minimization methods, earlier suggested algorithms for the solution of a many-electron problem in Hartree-Fock-Roothaan approximation for systems with close and open shells extend over Roothaan-Hartree-Fock atomic theory (Roothaan-Bagus method). In present work the expressions for energy derivatives with respect to elements of density matrices and nonlinear parameters of atomic orbitals — orbital exponents — have been obtained to solve Hartree-Fock (HF) equations in algebraic approximation. It is possible to create an algorithm of the first-order minimization or quasi-Newton method on their basis. Calculations of atoms and ions with several open shells were carried out by minimization methods. The energy values, close to the results of numerical solution of HF equations with high accuracy of virial relation, were gained using a sufficiently narrow basic set of Slater-type AO.     

Mesoionic compounds with a bridge nitrogen atom. 9. Imidazo[1,2-c]thiazoles

5-Methylthio-2-oxo-2,3-dihydro-1H-imidazo[1,2-c]thiazolium salts readily react with 3-ethylrhodanine, p-dimethylaminobenzaldehyde, and 3-ethyl-2-methylbenzothiazolium tosylate with the formation of polymethine dyes, including dyes with a mesoionic structure. Reaction with acetic anhydride has given acetyl-substituted imidazothiazolium 2-oxides.For communication 8, see [1].Translated from Khimiya (Geterotsiklicheskikh Soedinenii, No. 1, pp. 36–39, January, 1984.     

Differential-thermoanalytische Untersuchung von einigen Phosphororganischen Verbindungen

The thermal transitions of phosphines, phosphonium salts and esters of phosphorus acids, as well as some reactions of different phosphorus compounds, were studied by DTA.

1. DTA data have been considered for various types of reactions: 1. A→B; 2. A→B+C
2. DTA of reactive mixtures: 1. A+B→C; 2. A+B→C+D

Examples of the use of DTA were shown for studying the processes of isomerization, decomposition, and different regroup reactions of addition, combination, exchange and disintegration. The simple method of DTA allows one to find the optimum conditions of the reactions and to establish their reaction paths.