Low-temperature hydrodechlorination of 2,3-dichlorodibenzo-p-dioxin and chlorobenzene with hydrides catalyzed by transition metal compounds

Hydrodechlorination of chlorobcnzene by chemically bound hydrogen in the presence of transition metal compounds was studied. Alkali and alkaline earth metal hydrides (NaH, MgH₂, LiAlH₄, NaH(LiAlH₄)/12) were used as the sources of the chemically bound hydrogen. The effect of the natures of the hydride and of the transition metal on the activity was studied under comparable conditions. The Pd/C-NaH(LiAlH₄1/2 catalytic system was found to be the most active. This system made it possible to perform the quantitative dechlorination of 2,3-dichlorodibenzo-p-dioxin at 70 °C.Deceased.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1391–1394, June, 1996.     

Basicity and mechanism of transmission of electronic effects of substituents in the series of 2-amino-5-aryl-1,3,4-thiadiazoles

The basicity of 2-amino-5-aryl-1,3,4-thiadiazoles was studied. A correlation was obtained between the pK_BH+ values of the compounds and the constants of the substituents. It was shown that the electronic effects of the substituents in the phenyl ring are transmitted both on account of conjugation and by an induction mechanism.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 267–270, February, 1987.     

Flavonoids ofCaragana pygmaea

Chemistry of Natural Compounds -     

Peculiarities of interactions between the DNA molecule and different isomers and modifications of binuclear coordination compounds of platinum(II)

A comparison has been made of conformational changes in the DNA molecule during its interaction in solution with different binuclear coordination compounds of platinum [Pt(NH₃)₂Cl-R-Pt(NH₃)₂Cl]Cl₂ in cis and trans conformations, which contain cytosine, pyrazine, and carboxypyrazine as the common ligand (R). The influence of concentration of the components, and in particular, of ionic strength of the solution on the complexation process was studied. The influence of the nature of the common ligand, and of cis and trans conformations of coordination compounds on the character of their interaction with DNA was considered. A comparison was made between the structures of DNA complexes with mono-and binuclear compounds with the same set of ligands in the platinum coordination sphere.     

Estimates of the solutions of two-point boundary-value problems for systems of first-order integrodifferential equations and the method of lines

One proves theorems on the estimates of the solutions of the systems of first-order integrodifferential equations with the boundary conditions On the basis of these theorems, one suggests a method for estimating the norms of integrodifferential equations by the method of the lines for the solutions of the periodic boundary-value problems for second-order integrodifferential equations of parabolic type. On the basis of the established theorem, on the solvability and on the estimate of the solution of the nonlinear equation $$Tx + F\left( x \right) = 0$$ in a Banach space X, where T is a linear unbounded operator, one investigates the convergence of the method of lines for solving the periodic boundary-value problem for a second-order nonlinear integrodifferential equation of parabolic type.     

Synthesis of Substituted Methyl Pyridazine-4-carboxylates via Cycloaddition of Diazomethane to 2,3-Disubstituted 2-Cyclopropenecarboxylic Acids

A three-step procedure has been developed for the synthesis of 3,5-disubstituted methyl pyridazine-4-carboxylates from accessible 2,3-disubstituted 2-cyclopropenecarboxylates. In the first step, cyclopropene derivatives react with diazomethane to give adducts having 2,3-diazabicyclo[3.1.1]hex-2-ene structure. The regio- and stereoselectivity of the cycloaddition has been determined. The second step is isomerization of the bicyclic adducts into 1,4-dihydropyridazine derivatives by the action of sodium methoxide. Finally, oxidation with potassium permanganate yields the target pyridazine-4-carboxylates.     

Application of vibronic spectroscopy to conformational analysis. Investigations of molecules of carbonyl compounds

Application of vibronic spectroscopy to the conformational analysis of molecules in the ground and excited electronic states is reviewed. The basic concepts of the method as well as its methodological and technical aspects are discussed. The abilities of vibronic spectroscopy are exemplified by the results obtained for molecules of carbonyl compounds.The review is based on a report at the Vibrational Spectroscopy Conference dedicated to the 80th birthday of B. I. Stepanov (Minsk, Belarus', October 3–5, 1993).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 783–791, May, 1994.This work was performed with the partial financial support of the Russian.Universities State Program.