Specific features of the combustion of hydrogen-oxygen mixtures near the lower concentration flammability limit

The combustion of hydrogen-air mixtures near the lower composition flammability limit in cylindrical reactors of various diameters is studied. The speed of flame propagation in the horizontal direction is lower than that in the upward direction. Chromatographic analysis showed that, during the combustion of these mixtures, hydrogen is consumed only partially. That the flame propagates despite a low adiabatic temperature can be explained by the formation of the well-known cellular structure.     

Study of the extraction of strontium(II) and lead(II) by crown and dithiacrown ethers

A study was carried out on the extraction of strontium(II) and lead(II) picrates by chloroform solutions of crown and dithiacrown ethers. The benzene ring substituents in benzodithia-18-crown-6 only slightly affect the extraction of strontium and lead cations and their separation. The introduction of an adamantyl group onto the benzene ring markedly increases the extraction of lead and the separation selectivity of these cations. The use of dithia derivatives of benzo-18-crown-6 is less efficient for the extraction of both strontium and lead, though the selectivity of their separation is almost the same as in the extraction with benzo-18-crown-6.M. V. Lomonosov Moscow State University, 119899 Moscow. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1125–1129, August, 1997.     

Synthesis of Oxathiacrown Compounds by the Reactions of Sulfur Dichloride with Unsaturated Compounds and Their Extraction Characteristics. (Review)

Published data of the last 10-15 years on the use of the reactions of sulfur dichloride with various unsaturated compounds for the synthesis of oxathia- and thiacrown compounds and study of their extraction characteristics toward various transition and heavy metals are reviewed. Some previously unpublished results and associated experimental data are also included.     

First heteroleptic Mo<Subscript>3</Subscript>S<Subscript>7</Subscript> clusters containing non-innocent phenanthroline ligands

Reaction of the thiobromide [Mo₃S₇Br₆]²⁻ cluster anion with 5,6-dimethyl-1,10-phenanthroline (Me₂Phen) in solution leads to the substitution of two bromide ligands and the subsequent formation of a new mixed-ligand neutral complex [Mo₃S₇Br₄(Me₂Phen)] (I). Reaction of [Mo₃S₇Br₆]²⁻ with 5,6-dimethyl-1,10-phenanthroline in CH₂Cl₂ followed by treatment of I with Na(Dtc) · 3H₂O (Dtc = diethyldithiocarbamate) results in the new mixed-ligand cluster complex [Mo₃S₇(Dtc)₂(Me₂Phen)]²⁺ (IIa). Slow evaporation of the CHCl₃ solution of the complex in the presence of PF₆⁻ gives crystals of {[Mo₃S₇(Dtc)₂(Me₂Phen)]Br}PF₆ · 3CHCl₃ (II) characterized by X-ray structural analysis. Close contacts S...S result in the formation of cationic dimers {[Mo₃S₇(Dtc)₂(Me₂Phen)]₂}⁴⁺ which form infinite chains through additional S_ax...Br contacts. All compounds were characterized by IR, elemental analysis and ESI-MS. Synthesized complexes represent the first examples of heteroleptic Mo₃S₇ clusters containing phenanthroline ligands.     

Synthesis of 3-Aryl[1,2,4]triazolo[3,4-<Emphasis Type="Italic">b</Emphasis>][1,3]benzothiazole-6,7-dicarbonitriles from 5-Aryl-4H-triazole-2-thiols and 5-Bromo-5-nitrophthalonitrile

New 3-aryl-substituted [1,2,4]triazolo][3,4-b][1,3]benzothiazole-6,7-dicarbonitriles have been synthesized by successive interaction of 5-aryl-4H-triazole-2-thiols with 4-bromo-5-nitrophthalonitrile in the presence of K₂CO₃ initially at the bromine atoms and then at the nitro group.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, 270–272, February, 2005.     

Geminate Pairs and Their Role in Radiation-Induced Conductivity of Poly(methyl methacrylate)

Non-steady-state radiation-induced conductivity of poly(methyl methacrylate) was studied at room and elevated temperatures. It was shown that the conductivity is due to electric polarization of geminate pairs. The evolution of geminate pairs was rationalized in terms of the Rose–Fowler–Weisberg generalized model. The conclusions by the model were compared with the results of previous studies on the kinetics of formation and decay of geminate pairs upon pulse radiolysis or flash photolysis of doped poly(methyl methacrylate).     

Synthesis of chalcones from 3-formyl-substituted pyrrolo[3,4-<Emphasis Type="Italic">f</Emphasis>]indole-5,7-diones

General methods to access new 3-formyl-substituted 1-methoxypyrrolo[3,4-f]indole-5,7-diones were developed. The synthesized 3-formylindoles react with heterocyclic aceto-phenones under acid-catalyzed conditions to give different chalcones.