Efficient Tosylation of Dihydroxybenzenes in a Two-Phase Water–Dichloromethane System

Theoretical and Experimental Chemistry - The effect of the structure of the catalyst and the type of base on the reaction rate and product yield of the tosylation of dihydroxybenzenes in a...     

Structure and hydration of polycytidylic acid from the data of infrared spectroscopy, EHF dielectrometry and computer modeling

The aim of this paper is to summarize the original results concerned with the elucidation of the role of water environment in the formation of different structures of polyribocytidylic acid (poly(rC)), depending on the pH, temperature and ion content. To solve this problem, we studied the hydration of poly(rC)-K⁺ in films differing in water content, by methods of infrared spectroscopy and piezogravimetry, and in solution, using the dielectric measurements at a wavelength of 7.6 mm (extremely high frequencies — EHF). The experimental results were confirmed by a Monte Carlo simulation of the interaction between water molecules and single-strand and double-strand poly(rC) fragments in clusters of 800 water molecules. A model of hydration of double-strand complex of poly(rC)⁺-poly(rC) has been proposed based on our results and the known X-ray parameters of the complex. The obtained results and proposed structure of poly(rC)⁺-poly(rC) suggest that, the stabilization of this complex occurs due to intra- and inter-chain water bridges, together with the hydrogen bonds between neutral and protonated cytosines in pairs.     

Influence of the silver ions on the physicochemical properties of methyl methacrylate-methacrylic acid copolymer films

The effect of silver ions on the physicochemical properties of methyl methacrylate-methacrylic acid copolymer films, namely, film-forming properties and resistance to fluorine-containing plasma, acid etchers, and temperature, was studied by lithography, derivatography, atomic-force microscopy, and optical spectroscopy. The activation energies were calculated for thermal transformations in the copolymer with and without silver ion additions, when heated in air to 300°C.     

Statistical properties of cooperative emission of an ensemble of nonisochronous electrons–oscillators

Effect of shot noise and energy spread of particles on the statistical properties of cooperative emission of an ensemble of nonisochronous electrons–oscillators is analyzed. The dependences of the rootmean-square deviation of the peak radiation power and the autophasing time on the number of particles are determined in the absence of the energy spread. Even a minor energy spread of 4% leads to a decrease in the maximum possible power of cooperative emission.     

Synthesis of C-phosphorylated benzenesulfonyl-containing acetamidines

Reactions of sodium derivatives of C-phosphorylated acetamidines with benzenesulfonyl chloride were studied. The reactions proceed selectively to form benzenesulfonyl-containing acetamidine derivatives. A convenient method for the synthesis of a new type of C-phosphorylated acetamidines was developed utilizing CH-acid properties.     

Condensation of N-substituted alkyl(dibutoxyphosphoryl)acetimidates with tribromoacetaldehyde

N-Substituted alkyl(dibuthoxyphosphoryl)acetimidates enter into the reaction with tribromoacetaldehyde under mild conditions without catalyst to form products of addition to the carbonyl group, N-substituted ethyl-(4,4,4-tribromo-3-hydroxy-2-dibutoxyphosphoryl)butanimidates.