Interaction of Nitromethane with Modified Paramagnetic Defects on a Thermochemically Activated Silica Surface

It was found that the interaction of the modified paramagnetic defects SiO(CH₂) _n H₂ (n = 0.1) with nitromethane on a thermochemically activated silica surface at 300 K results in the formation of the following nitroxyl radicals: SiO(CH₂) _n CH₂ON( )CH₃ and SiO(CH₂) _n CH₂N( )CH₃. It was suggested that these radicals are the products of two different reactions of the modified paramagnetic defects: the first results from a reaction with free nitromethane; the second, from a reaction with nitromethane bound as complexes with diamagnetic surface defects.     

Elimination of bremsstrahlung in activation analysis by the deflection of β-particles in a magnetic field

The structureless background at X-ray and low energy -ray region, resulting from bremsstrahlung due to the stopping of -radiations, causes serious problems in nuclear spectroscopy. In this study, in order to reduce the background and therefore to increase the sensitivity of the nuclear analytical technique and the number of elements observable, a methodology is developed to deflect the -particles by a magnetic field. The experimental setup consists of a permanent magnet /1 kG/, Ge/Li/ solid-state detector, and multichannel analyzer.     

Kinetic CH-acidity of benzenetricarbonylchromium and its derivatives

Kinetic acidities of aryl and benzyl CH-bonds for complexes of benzene and its methoxy and alkyl derivatives with tricarbonylchromium are determined in a solution of lithium tert-butoxide in N,N-dimethylacetamide. Complexation of alkyl-aromatic compounds to the Cr(CO)3 group increases the lability of the aryl CH-bond by 107–109 times and that of the benzyl bond by 5·10⁴–5·10⁵ times. The Cr(CO)₃ group in arene complexes neutralizes the effect of other substituents regardless of their nature and position in the molecule.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2458–2461, November, 1989.     

Benzindoles. 23. 2-formyl- and 3-formyl-4,5-benzindoles

It is shown that, in addition to the usually formed 3-formyl-4,5-benzindole, 2-formyl-4,5-benzindole can be obtained via the Vilsmeier reaction. The IR, PMR, and UV spectra of the 2- and 3-formyl isomers are compared, and their possible conformations are discussed.See [1] for Communication 22.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 343–345, March, 1984.     

Effect of zirconium,calcium, and barium on corrosion-electrochemical behavior of aluminum

The effect of zirconium, calcium, and barium on corrosion-electrochemical properties of aluminum was studied. A positive effect of alloying aluminum by these metals was revealed.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 11, 2004, pp. 1815–1818.Original Russian Text Copyright © 2004 by Ganiev, Barotov, Inoyatov.     

Photophysical properties of poly-2-phenyl-5-(p-vinyl)-phenyloxazole

2-Phenyl-5-(p-vinyl)phenyloxazole (POS) has been synthesized. Copolymers of POS with styrene and the homopolymer poly–POS have been prepared. The polymers have been characterized through measurements of fluorescence decay times (using synchrotron radiation for excitation) and examination of excimer formation in the homopolymer. Fluorescence decay times of 0.6(±0.4) nsec and 9 (±0.2) nsec have been recorded at 298°K in toluene solution for monomer and excimer, respectively. Poly-POS exhibits excimer formation characterized by an activation energy of 5.9(±0.5) kJ/mole and a binding energy of 17.0(±1.0) kJ/mole.     

Phosphorylthioacetamides in the synthesis of annulated quinoxalines

Diethoxyphosphorylthioacetamide in the reaction with 2,3-dichloroquinoxaline acted as a thionating reagent, giving diethoxyphosphorylacetonitrile and 2-chloro-3-[(3-chloro-2-quinoxalinyl)thio]quinoxaline. Reactions of phosphorylthioacetamides with N-methylquinoxalinium iodide in alcohol media in the presence of a base proceeded stereoselectively to afford cis-3-phosphoryl-1,3,3a,4,9,9a-hexahydro-2H-pyrrolo[2,3-b]quinoxaline-2-thiones. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1010–1013, May, 2007.     

Potentiometric Determination of Ascorbic Acid: Estimation of Its Contribution to the Total Antioxidant Capacity of Plant Materials

It was found that an iodine-modified platinum electrode gives a linear potentiometric response to 1.0 × 10^–5 to 1.0 × 10^–3 M ascorbic acid in model solutions. Ascorbic acid in some preparations was determined by potentiometry. The contribution of ascorbic acid to the total antioxidant capacity of aqueous extracts of hips, hop cones, and lemon juice was estimated.     

Delocalization model of regioselectivity and reactivity of free radicals in reactions of addition to olefins

On the basis of the concept of polarity (philicity) of free radicals as proposed by the authors, within the framework of methods of qualitative surfaces of potential energy (linear combinations of configurations of fragments) and stabilization energy, an effective model has been developed for the regioselectivity and reactivity of radicals in processes of addition. A critical examination is made of certain key aspects of the change in regiochemistry and reactivity with changes in the electronic structure of the free radical and substrate. The dominant trends in regioselectivity and reactivity in processes of free-radical addition to olefins are controlled by electronic effects and can be predicted by analyzing interactions of diabatic potential energy surfaces or orbital interactions for a system consisting of a free radical and an unsaturated substrate.Presented at 3rd All-Union Symposium Dynamics of Elementary Atomic-Molecular Processes (Chernogolovka, June 1985) and at the 9th All-Union Conference on Quantum Chemistry (Ivanovo, June 1985).Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 23, No. 2, pp. 135–148, March–April, 1987.The authors are grateful to M. V. Bazilevskii for his constructive discussion of the results obtained in this work.     

C-substituted diethyleneimides of acids of phosphorus

Conclusions We have obtained the hitherto undescribed 2,2-dimethyl- and 2-ethylethyleneimides of alkylphosphorous acids and, by addition of sulfur and selenium to these compounds, the corresponding ethyleneimldes of alkylthio-and selenophosphoric acids.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1143–1144, May, 1968.