Photochemical synthesis of heteroatom-containing polycyclic aromatic compounds

Anthra[2,1-b]furan, anthra[2,1-b]benzo[d]furan, anthra[2,1-b]thiophene, anthra[1,2-b]thiophene, anthra[2,1-b]benzo[d]thiophene, anthra[2,1-b]pyrrole and naphtho[2,3-c]carbazole derivatives were synthesized in fairly good yields by a one-pot photocycloaddition reaction of 2,3-disubstituted 1,4-naphthoquinone with 1,1-diarylethylene. This is the first reported synthesis of these aromatic compounds.     

Photochemical reactions of organomercury compounds in organic solvents

The quantum yields of photolysis of organomercury compounds in different organic solvents have been measured. It was shown that the quantum yields of photolysis of nitro derivatives of mercury compounds and the symmetric (methylnaphtyl)mercury compound are equal to unity. The photolysis of halo derivatives of benzylmercury proceeds with lower quantum yields as compared with photolysis of analogous dibenzylmercury derivatives. The quantum yields of photolysis of organomercury compounds are almost independent of the solvent.     

Photochemical oxidation of 1,2,2,6,6-pentamethyl-4-piperidol by ketones

Chemistry of Heterocyclic Compounds -     

Photochemical oxidation of 4h-seleno(thio)pyrans

Oxidation of solutions of 4H-thiopyrans and 4H-selenopyrans to the corresponding heteroaromatic cation bromide occurs on irradiation with ultraviolet light in the presence of CBr₄. Reaction takes place by a free radical chain mechanism. The presence of CHBr₃ and C₂Br₆ in the reaction mixture was detected chromatographically.N. G. Chennyshevskii Saratov State University, Saratov 410026, Russia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 749–751, June, 1999.     

Photochemical and radical initiator-induced reaction of allylic indium compounds

Intramolecular cyclization of allylic radicals generated from allylindium compounds both by photolysis or by the reaction of radical initiators was examined. The photolysis of allylic indium compounds, prepared from 8-bromo- or 8-iodooct-1,6-dienes and powdered indium metal, led to the formation of the 5-exo-trig products. Benzoyl peroxide as a radical initiator was also effective for the cyclization. In contrast, the radical initiators with oxidizing nature, such as tert-butyl hypochlorite, induced iodocyclization producing iodomethylcyclopentane via an oxidation of the iodide on the indium atom.     

Photochemical addition of trialkylsilanethiols and trialkylgermanethiols to acetylenic compounds

Conclusions The addition reaction of trialkylsilane- and trialkylgermanethiols leads to the formation of the corresponding trialkylsilyl and trialkylgermyl (-organyl) vinyl sulfides in high yield.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1413–1415, June, 1976.     

The oxidation of organic compounds

In a study of the behavior of tris(hydroxymethyl)-4-picoline (I) under the conditions of vapor-phase oxidation on a vanadium-tin oxide catalyst, it was found that with the addition of 150–250 mole of water and 125–200 mole of O₂ per mole of I and a contact time of 0.35–0.45 sec, the main reaction product was isonicotinic acid (II), the yield of which amounted to 60–65% of theoretical, calculated on the I passed.For part XLVIII, see [1].     

Aerobic oxidation of organic compounds catalyzed by vanadium compounds

Aerobic oxidation of α-hydroxy ketones catalyzed by dichloroethoxyoxovanadium in ethanol causes a carbon–carbon bond cleavage that produces diesters or diketones. This reaction is highly chemoselective, and disecondary glycols do not react at all. However, ditertiary glycols effectively react with dichloroethoxyoxovanadium or trichlorooxovanadium to provide the corresponding ketones. Aerobic oxidation of α-hydroxy ketones catalyzed by dichloroethoxyoxovanadium or trichlorooxovanadium in aprotic solvents almost quantitatively affords the corresponding α-diketones. The reaction of tertiary cyclopropanol compounds with vanadyl acetylacetonate under an oxygen atmosphere causes fragmentation of the cyclopropane moiety to produce β-hydroxy ketones and β-diketones. For the 6-substituted bicyclo[4.1.0]heptanol derivatives, the endoperoxides are also obtained together with β-hydroxy ketones. Conversely, 2-ethoxycarbonylcyclopropyl silyl ethers produce γ-oxocarboxylate derivatives given the same reaction conditions. Monothioacetals are easily deprotected into carbonyls using a catalytic amount of trichlorooxovanadium in 2,2,2-trifluoroethanol under an oxygen atmosphere. Thiols are converted into the corresponding disulfides by the aerobic oxidation catalyzed by trichlorooxovanadium in the presence of molecular sieves 3A. Polymer-supported vanadium compounds are synthesized by the reaction of vanadium oxytrichloride with polymers bearing hydroxyl moieties. The catalyst prepared from TentaGel S OH was highly active and reusable for the aerobic oxidations.     

Photochemical vulcanization of siloxane rubber with compounds containing silicon-silicon bond

Certain deformation-strength properties of vinyl-containing siloxane rubber cured with oligomeric and polymeric compounds containing silicon-silicon bonds and with dicumyl peroxide were studied.     

Photochemical synthesis of a water oxidation catalyst based on cobalt nanostructures

New cobalt-based nanocomposites have been prepared by photoreduction of Co(2+) salts to generate cobalt nanoparticles deposited on carbon-based materials such as nanocyrstalline diamond and carbon felt. Spontaneous air oxidation converts the metal to Co(2)O(3) which has been tested as a water oxidation catalyst. This work demonstrates that the cobalt oxide nanostructures can be deposited on various carbon surfaces and can catalyze the four-electron oxidation of water to oxygen under anodic bias.     

Electrochemical oxidation of aliphatic polynitro compounds

Conclusions Trinitromethyl radicals formed in the electrooxidation of the trinitromethane anion are capable of stripping a hydrogen atom from the methyl group of toluene, as well as recombining with the benzyl and methyl radicals, forming the corresponding trinitro derivatives.For Communication 1, see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1717–1721, August, 1972.     

Enzyme catalysed oxidation of ferrocene compounds

A facile transformation of ferrocene and a series of substituted ferrocenes to the corresponding ferricinium ions has been effected by hydrogen peroxide in the presence of the native or immobilized enzyme horseradish peroxidase.     

Photochemical oxidation of hydrocarbons by a vanadium(V) peroxo complex

The oxidation of alkanes and benzene by VO(O₂)L·2H₂O (L=2-picolinate) in acetonitrile is accelerated upon irradiation with visible and, especially, UV light. Cyclohexyl hydroperoxide, cyclohexanol, and cyclohexanone in approximately 2:1:1 ratio are formed from cyclohexane both in the dark and photochemical reactions. Benzene is oxidized to phenol.Istituto di Teoria e Struttura Elettronica dei Composti di Coordinazione, CNR, Area della Ricerca di Roma, via Salaria km 29.5, C. P. 10, 00016 Monterotondo Stazione, Rome, Italy. N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 117977 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1918–1921, August, 1992.