One-Pot Formation of Carbonates from the Reactions of Carbonyl Compounds with Samarium Diiodide and Methyl Chloroformate

Treatment of carbonyl compounds with SmI₂ and methyl chloroformate in the presence of molecular sieves provides the cyclic carbonates or biscarbonates of pinacols. This one-pot reaction proceeds rapidly even with aliphatic ketones. The stereochemistry obtained by this procedure is different from that of conventional pinacolic couplings.     

Structure and reactivity of benzothiazole-2-thione polysulfides

A quantum-chemical study was made of the possibility of the formation of polysulfides from benzothiazole-2-thione and their structure. The reactivity indices of the benzothiazole-2-thione molecule and of the small sulfur fragments were calculated. It was shown that as the fragments approach each other the formation of polysulfide structures with increased reactivity becomes possible.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 26, No. 1, pp. 73–78, January–February, 1990.     

Synthesis and properties of benzyl-substituted thiiranes

The reaction of phenyl- and p-tolylmagnesium bromides, as well as di, tri, and tetramethylbenzene, with epichlorohydrin was used to synthesize the corresponding chlorohydrins, which were then converted to various benzyl-substituted oxiranes and thiiranes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 598–602, May, 1988.     

Synthesis and analytical application of tribromocarboxyarsenazo as a new chromogenic reagent for zirconium

A new chromogenic reagent tribromocarboxyarsenazo has been synthesized and the chromogenic reaction of this reagent with zirconium studied. In the medium of 0.5 mol/1 HCl, a blue complex is formed by the reaction of zirconium with tribromocarboxyarsenazo. The maximum absorption of the complex is at 633 nm, and the apparent molar absorptivity is 4.8 x 10(4) 1/mol/cm. Beer's law is obeyed over the zirconium concentration range 0-18, mug/25 ml. The method has been applied to the determination of zirconium in aluminum, copper and magnesium alloys with satisfactory results.     

Dichloro bis(η5) molybdenum catalysed reduction of organic halides by sodium borohydride

Summary Dichloro bis(⁵) molybdenum catalyses the reduction of organic halides by sodium borohydride smoothly and selectively. The reactions with representative organic monohalides and polyhalides are investigated. The ease of reduction depends on the structure of the halide and the solvent used. alkoxycarbonyl and cyano groups are unattacked in the reaction. An oxidative addition-reductive elimination mechanism is tentatively suggested.     

Flow Sorption–Spectroscopic Analysis

Combinations of the dynamic sorption preconcentration of elements with spectroscopic determination techniques was considered. The use of sorption systems in flow spectroscopic techniques are discussed, and the evaluation of the efficiency of these systems in the preconcentration of elements is described. The application of flow sorption–spectroscopic techniques to the determination of elements in natural water, drinking water, soil, food stuffs, rocks, and ores is surveyed.     

Structure of convosine

From the roots of the plantConvolvulus subhirsutum Regel et Schmalh. have been isolated seven known alkaloids and one new one, for which, on the basis of spectral characteristics, a comparative study with known alkaloids of the tropane series, and synthesis, the structure of (+)-N-isopropyl-3-veratroyloxynortropane has been established.Institute of the Chemistry of Plant Substances of the Uzbek Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 618–620, September–October, 1986.     

Hoffmann's method applied to ethylene oxide,ethylenimine, cyclopropane,and cyclopeopyl ethers

The method is applied to six compounds each containing a three-membered ring. It is found that a cyclopropane ring interacts with ether oxygen attached to it to give some of the features of a -electron system. Inclusion of N or O in the three-membered ring lowers the top filled and bottom vacant levels, especially the latter.     

Pushing the detectability of voltammetry: how low can we go?

The coupling of adsorptive accumulation with catalytic reactions results in remarkably low (sub-picomolar) detection limits. This review assesses various strategies for attaining such dual-amplification effects, that lead to the most sensitive voltammetric technique, adsorptive-catalytic stripping voltammetry (AdCtSV).