Electrochemical synthesis of niobium compounds in anodic dissolution of ferroniobium in methanol

Anodic dissolution of ferroniobium in anhydrous methanol in the presence of sodium methylate was studied. The possibility of recovering pure hexamethoxyniobate from the electrolyzate and its conversion into niobium methylate with an iron content not exceeding 0.01% was analyzed.     

Electrochemically induced processes in the formation of phosphorus acid derivatives. 2. The role of polymerization processes in the electrosynthesis of the esters of phosphorus acids from white phosphorus

The mechanism of the electrosynthesis of phosphate esters from white phosphorus was investigated. It was shown that the reaction takes place by two paths, i.e., monomeric (with the participation of dissolved phosphorus) and polymeric (with the participation of phosphorus on the surface of an emulsion drop). It was established that in an alcohol solution of tetraethylammonium iodide the main part of the final product is formed through an intermediate polymeric compound. It was noticed that by studying the dynamics of the accumulation of the dissolved product during electrolysis it is possible to trace the mechanism of reaction of the phosphorus at the individual stages of the process.A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan' Scientific Center, Russian Academy of Sciences, 420028 Kazan'. V. I. Ul'yanov-Lenin Kazan' State University, 420028 Kazan'. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1328–1333, June, 1992.     

Synthesis and spectroscopic study of hexadecaalkyl-substituted rare-earth diphthalocyanines

New hexadecaalkyl-substituted diphthalocyanine complexes of lanthanides ^RPc₂Ln (R = Et, or Bu; Ln = Lu, Dy, or Eu) were synthesized by three methods: in solution in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene, in a melt of a mixture of the reagents, and under microwave irradiation. The first of the above-mentioned procedures has an advantage for the preparation of Dy and Eu diphthalocyanines, whereas the melt synthesis is a method of choice for the preparation of Lu complexes. The reaction time decreases in going from the first to the third method. The structures of the complexes were confirmed by mass spectrometry, NMR spectroscopy, and electronic absorption spectroscopy.     

Synthesis and transformations of metallacycles. 23. Cp2TiCl2-Catalyzed cyclometallation of fullerene C60 with EtAlCl2

1-Ethyl-2,3-fullerenoaluminacyclopropanes (EtAl)_n(²-C₆₀) were synthesized by the reaction of fullerene C₆₀ with an excess of EtAlCl₂ in the presence of Mg and using Cp₂TiCl₂ as the catalyst in a THF--toluene solution at 20 °C. Deuterolysis of fullerenoaluminacyclopropanes afforded a mixture of deuteriofullerenes C₆₀D_m, where m = 6--12.     

Addition of diazocyclopropane generatedin situ to vinyl bromide and chemical transformations of the resulting 5-bromospiro(1-pyrazoline-3,1′-cyclopropane)

The reaction of diazocyclopropane generatedin situ with vinyl bromide occurs as regioselective 1,3-dipolar cycloaddition to give 5-bromospiro(1-pyrazoline-3,1′-cyclopropane) in ∼60% yield. Reactions of the latter with nucleophilic reagents, which can occur both with retention and opening of the cyclopropane ring, were studied. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 688–690, April 1998.     

Decomposition of N-cyclopropyl-N-nitrosourea in the presence of reducing agents as a new way of generating the cyclopropyl radical

A new way of generating cyclopropyl radicals in the base-catalyzed decomposition of N-cyclopropyl-N-nitrosourea in the presence of organic reducing agents (1-phenylpyrazolidin-3-one and 4-methoxyphenol) was developed. The cyclopropyl radical generated under these conditions can not only abstract a proton from the substrate to give cyclopropane but also form C-C or C-Br bonds in reactions with aromatic substrates or polybromomethanes. Dedicated to Academician O. M. Nefedov on the occasion of his 75th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1934–1938, November, 2006.     

Addition of diazocyclopropane generatedin situ to acrylic acid derivatives and transformations of resulting functionally substituted spiro(pyrazolinecyclopropanes)

The reaction of diazocyclopropane generatedin situ with acrylonitrile or methyl acrylate to give 1∶1, 1∶2, and 2∶1 cycloadducts was carried out. The products resulting from 1,3-dipolar cycloaddition and subsequent isomeriation,viz., 3-cyano- and 3-methoxycarbonylspiro(2-pyrazoline-5,1′-cyclopropanes), isolated in the first step in ∼70% yield, react in an alkaline solution with the above acrylates or diazocyclopropane as C(3)-nucleophiles to give the corresponding 3-(2′-cyanoethyl)-, 3-(2′-methoxycarbonylethyl)-, or 3-(cyclopropylazo)-1-pyrazolines. The thermal deazotization of these pyrazolines to spiropentane derivatives was investigated. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 532–539, March, 1997.     

Acylation of fluorine-containing spiro[cyclopropane-1-pyrazolines] and dehydrohalogenation of the resulting adducts

Acylation of 6-(1-fluorovinyl)-6-methyl- and 6-(2,2,3,3-tetrafluorocyclobutyl)-4,5-diazaspiro[2.4]hept-4-enes with acetyl chloride proceeds as electrophilic addition to the N(5) atom and is accompanied by opening of the cyclopropane ring to give 1-acetyl-3-(2-chloroethyl)-5-(1-fluorovinyl)-5-methyl- and 1-acetyl-3-(2-chloroethyl)-5-(2,2,3,3-tetrafluorocyclobutyl)-4,5-dihydropyrazoles, respectively. Under the same conditions, acylation of 6-(2,3,3-trifluorocyclobut-1-enyl)-4,5-diazaspiro[2.4]hept-4-ene is not regioselective. The (2-chloroethyl) pyrazolines obtained undergo dehydrochlorination into vinylpyrazolines in the presence of an excess of MeONa in MeOH. The reaction of 4-acetyl-6-(2,3,3-trifluorocyclobut-1-enyl)-4,5-diazaspiro[2.4]hept-5-ene with MeONa results in selective replacement of the F atom at the double bond by a methoxy group.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 419–422, February, 2005.     

Voltammetric studies of the Kolbe synthesis with perfluorocarboxylic acids prepared from hexafluoropropene oxide oligomers

Carboxylic acids prepared from hexafluoropropene oxide CF₃CF₂CF₂O[CF(CF₃)CF₂O]_nCF (CF₃)COOH [n = 0, 2,5-bis(trifluoromethyl)-3,6-dioxaperfluorononanoic acid; n = 1, 2,5,8- tris(trifluoromethyl)-3,6,9-trioxaperfluorododecanoic acid], according to voltammetric data, enter the Kolbe reaction both at the Pt anode and at anodes from carbon materials in H₂O-CH₃CN and CH₃OH-CH₃CN solutions. The critical potential appreciably depends both on the anode material and on the solvent composition. Favorable effect of pyridine additions in H₂O-CH₃CN solutions is due to replacement of water molecules from the electrical double layer. The sodium ions exert a negative effect on the Kolbe synthesis.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 11, 2004, pp. 1842–1846.Original Russian Text Copyright © 2004 by Chechina, Sokolov, Tomilov.This revised version was published online in April 2005 with a corrected cover date.