Breakage of λ-DNA by inorganic tin and organotin compounds as environmental pollutants

In proportion to the environmental pollution problems caused by organotin compounds, the genotoxicities of tin compounds in the environments have become of interest so as to estimate their safety in recent years. In this work, isolated λ-DNA (double-strand DNA) was incubated with inorganic tin(II) and tin(IV) and five organotin compounds [n-butyltin trichloride, di(n-butyltin) dichloride, methyltin trichloride, dimethyltin dichloride and trimethyltin chloride] in reaction systems both with and without hydrogen peroxide (H₂O₂) content. The tin compounds tested in this study did not induce DNA breakage in the absence of hydrogen peroxide. Divalent inorganic tin (SnCl₂) and tetravalent inorganic tin (SnCl₄) caused DNA breakage in the presence of hydrogen peroxide (10 mM), and the DNA damage activity of inorganic tin was much more potent in divalent inorganic tin (SnCl₂) than in tetravalent inorganic tin (SnCl₄). Divalent inorganic tin (SnCl₂) induced DNA breakage in a concentration-dependent fashion at concentrations greater than 0.1 mM of SnCl₂ in the presence of hydrogen peroxide (10 mM). DNA breakage was not caused by n-butyltin compounds and methyltin compounds either in the presence or in the absence of hydrogen peroxide.     

Ti－Si沸石的催化氧化性能Ⅱ．环己醇的氧化及环己酮的肟化

Ｔｉ－Ｓｉ沸石的催化氧化性能Ⅱ．环己醇的氧化及环己酮的肟化夏清华，王公慰，应慕良，郑禄彬（中国科学院大连化学物理研究所，大连１１６０１２）关键词Ｔｉ－Ｓｉ沸石催化剂，Ｈ_２Ｏ_２氧化剂，环己醇氧化，环己酮肟化．１．前言环己酮肟是生产ε－己内酰胺的关键中...     

Asymmetric Baeyer—Villiger oxidation: control of stereoelectronic demand

The recent development of asymmetric Baeyer—Villiger oxidation of prochiral and racemic ketones is briefly summarized, focusing on the regio- and stereocontrol of the oxidation attained by regulating the stereoelectronic demand in the step of rearrangement of the Criegee intermediate.Based on the report presented at the International Conference Modern Trends in Organoelement and Polymer Chemistry dedicated to the 50th anniversary of the A. N. Nesmeyanov Institute of Organoelement Compounds of the Russian Academy of Sciences (Moscow, May 30–June 4, 2004).Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1784–1794, September, 2004.     

FT IR ATR Study of Molecular Interactions in the Urea/Dimethyl Sulfoxide and Urea/Diethyl Sulfoxide Binary Systems

FT IR ATR spectra of urea/dimethyl sulfoxide and urea/diethyl sulfoxide mixtures in the S=O and N—H stretching vibration regions at different molar ratios have been measured. On the basis of the band deconvolution data, various types of intermolecular associated forms, including dimers and hydrogen-bonded urea–sulfoxide complexes, have been revealed. The latter has been confirmed also by ab initio calculations.     

A spectroscopic study on the 12-heteropolyacids of molybdenum and tungsten (H3PMo12−nWnO40) combined with cetylpyridinium bromide in the epoxidation of cyclopentene

The epoxidation of cyclopentene with hydrogen peroxide catalyzed by 12-heteropolyacids of molybdenum and tungsten (H₃PMo_12−nW_nO₄₀, n = 1–11), 12-tungstophosphoric acid and 12-molybdophosphoric acid combined with cetylpyridinium bromide as a phase transfer reagent was carried out in acetonitrile. Among 13 heteropolyacids investigated, catalyst of H₃PMo₆W₆O₄₀ showed the highest activity, giving a conversion of 60% and a selectivity of 95% in the epoxidation of cyclopentene. The fresh catalysts and the catalysts under reaction condition were characterized by UV–vis, FT-IR and ³¹P NMR spectroscopy, which has revealed that all of the molybdotungstophosphoric acids were degraded in the presence of hydrogen peroxide to form a considerable amount of phosphorus-containing species. The active species resulted from H₃PMo₆W₆O₄₀ are new kinds of phosphorus-containing species, which is different from {PO₄[WO(O₂)₂]₄}³⁻.     

Thermal and structure analysis of FeSO4·H2O-BaO2 mixtures

Investigations on the thermal decomposition of FeSO₄·H₂O-BaO₂ mixtures were carried out under isothermal conditions by using simultaneously solid electrolyte cell (EMF-method). Evoked interactions producing oxygen in the temperature range 553-673 K were established by means of a solid electrolyte oxygen analyzer. Based on Mössbauer spectroscopy data and X-ray analysis it was proved that these reactions were associated with the release of oxygen from barium peroxide, oxidation of ferrosulphate-monohydrate to FeOHSO₄, and formation of barium ferrites such as BaFe₂O₄ and BaFe₁₂O₁₉.     

Chemihiminescence by the interaction of XeO3 and the products of photolysis of uranyl solutions in sulfuric acid

Using the chemiluminescence oxidation of U(IV) and H₂O₂ with xenon trioxide as a model, it has been found that during the photolysis of solutions of UO₂SO₄ in sulfuric acid in the absence of any organic compounds, the accumulation of U(SO₄)₂ and H₂O₂ takes place as a result of the reaction of the primary products of the photoreduction of uranyl ion,i.e., UO₂ ⁺ and the OH radical.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 751–754, April, 1994.The work was financially supported by the Russian Foundation for Basic Research, Project 93-03-12291.     

Alkane oxygenation with H2O2 catalysed by FeCl3 and 2,2′-bipyridine

The H₂O₂-FeCl₃-bipy system in acetonitrile efficiently oxidises alkanes predominantly to alkyl hydroperoxides. Turnover numbers attain 400 after 1 h at 60 °C. It has been assumed that bipy facilitates proton abstraction from a H₂O₂ molecule coordinated to the iron ion (these reactions are stages in the catalytic cycle generating hydroxyl radicals from the hydrogen peroxide). Hydroxyl radicals then attack alkane molecules finally yielding the alkyl hydroperoxide.     

Water as an Efficient Solvent for Oxygenation Transformations with 34% Hydrogen Peroxide Catalyzed by some Heteropolyoxometalates

Summary. A highly efficient, selective, fast, and cheap protocol is developed for oxidation of aromatic amines and alcohols utilizing 34% hydrogen peroxide in water catalyzed by some W- and Mo-based heteropolyoxometalates. Findings showed that dodecatungstophosphoric acid, H₃PW₁₂O₄₀, was the most efficient catalyst in the examined oxidation reactions. This methodology may prove to be a valuable alternative for eco-friendly green oxidation. Inherent simplicity, easy work up, and using regenerable catalysts were other key aspects of this oxidation protocol.     

Nucleophilic reactivity of the peroxide anion in aqueous-alcoholic solutions in the presence of detergents

The reactivity of hydroxide and peroxide anions with 4-nitrophenyl N,N-dimethylcarbamate in aqueous-alcoholic detergent media and in “oil in water” microemulsions has been studied. Aqueous-alcoholic solutions of cationic (CTAB) and neutral (Triton X-100) surface active substances have promise for decomposition of substrates by a nucleophilic mechanism. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 43, No. 6, pp. 358–363, November–December, 2007.