Synthesis of 1,2-bis(methoxyamino)cycloalkanes from alicyclic 1,2-bis(hydroxyamines)

Derivatives of 1,4-dihydroxypiperazine-2,3-dione were obtained by reaction of cis-1,2-bis(hydroxyamino)cycloalkanes with diethyl oxalate. Their alkylation with CH₂N₂ or Mel afforded 1,4-dimethoxypiperazine-2,3-diones. Hydrolysis of the latter gave 1,2-bis(methoxyamino)cycloalkanes.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 925–929, April, 1996.     

The Mitsunobu 1-O-esterification of 1-hydroxy-3-phenyl-1H-quinoxalin-2-one 4-oxide

1-Hydroxy-2-oxo-3-phenyl-1,2-dihydroquinoxaline 4-oxide under conditions of the Mitsunobu reaction reacts with alcohols giving the corresponding esters at the hydroxy group in position 1. Other representatives of hydroxamic acids such as 1,4-dihydroxyperhydroquinoxaline-2,3-dione and 1,4-dihydroxy-3,3,6,6-tetramethylpiperazine-2,5-dione undergo destruction under these conditions. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1240–1243, June, 2008.     

Thermal stability of carboxylate salts

A correlation between the temperatures of the maximum thermal decomposition rate of salts or of the maximum heat effects, and the standard heats of formation of the respective metal oxides has been established.

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On the problem of predicting the activity of oxide and carbonate catalysts in some reactions of petrochemical synthesis

The problem of predicting the activity of oxide and carbonate catalysts for some reactions of petrochemical synthesis (vapor phase conversion of carboxylic acids, catalytic oxidation of asphaltic tar to bitumen) according to the established dependence of thermal stability variations of intermediates on the formation enthalpy of metal oxides or standard ele.trode potentials is discussed.

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Langmuir-blodgett films on the basis of an amphiphilic nitronylnitroxyl radical

The 2-(4-hexadecylmethylamino)phenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxy-3-oxide radical, which contains a long alkyl chain and a strong donor substituent conjugated with a nitronyl nitroxide group (an acceptor), was synthesized. The behavior of monolayers formed by this radical on a water surface and the conditions of their transfer onto solid substrates by the Langmuir-Blodgett method were examined. UV-VIS and IR spectroscopies, atomic force microscopy, and small-angle X-ray scattering were used to study the optical and structural characteristics of films prepared from the pure radical and its mixtures with behenic acid. It was revealed that radical aggregates are formed both in solutions and Langmuir-Blodgett films.     

Solvent-controlled organization of self-assembled polymeric monolayers on gold: an easy approach for the construction of protein resistant surfaces

Protein resistant surfaces based on poly(ethylene glycol) (PEG) coatings are extensively applied in the fields of biosensors, tissue engineering, fundamental cell-surface interaction research, and drug delivery systems. The structural organization of the PEG film on the surface has a significant effect on the performance of the film to resist protein adsorption. In this paper, we report an approach using solvent to control the organization of the polymeric monolayer on gold. A water soluble copolymer with grafted PEG side chains and alkyl disulfide side chains was synthesized. A polymeric monolayer was fabricated on a gold surface from different solutions (water- and toluene-based) of the copolymer. The organization of the polymeric monolayers was characterized by means of ellipsometry, cyclic voltammetry, contact angle, X-ray photoelectron spectroscopy, and atomic force microscopy. It was proven that the structural organization of the polymeric monolayer on a gold surface could be controlled by the solvent. A polymeric monolayer with PEG enriched at the outer level is obtained when water is used as the solvent. Various types of proteins, including fibrinogen, albumin, and normal human serum, were used to test the protein resistance of the gold surfaces modified by the polymeric monolayers. The polymeric monolayer formed from a water solution of the copolymer showed excellent protein resistance. In addition, by using water as the solvent, patterning of the polymeric monolayer could easily be achieved through a combination of lift-off and self-assembly. We believe that the approach reported here provides an easy, fast, and efficient way to fabricate a robust protein resistant surface.     

Interfacial surface properties of thiol-protected gold nanoparticles: a molecular probe EPR approach

We present a molecular probe technique for accessing interfacial surface electrostatics of ligand-protected gold nanoparticles. A series of ligands with variable length of the hydrocarbon bridge between the anchoring sulfur and the reporting pH-sensitive nitroxide is described. The protonation state of this probe is directly observed by EPR spectroscopy. For tiopronin-protected Au nanoparticles, we observed an increase in pKa of up to ca. 1.1 pH units that was affected by the position of the reporter moiety with respect to the monolayer interface.     

Investigation of catalysts for thermal conversion of alkaline salts of benzenecarboxylic acids

Thermal decomposition of cadmium and zinc salts of benzenecarboxylic acids as catalysts for the thermolysis of alkaline salts of the same acids have been studied.

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Langmuir-blodgett films of hydroxamic acid of the quinoxalinone series

Amphiphilic hydroxamic acid 2-(4-decyloxyphenyl)-4-hydroxy-3-oxo-3,4-dihydroquinoxalin-1-oxide was synthesized. The conditions of the formation of hydroxamic acid and its lead, europium, cadmium, and copper salt monomolecular layers were studied. Multimolecular systems were prepared by the Langmuir-Blodgett method from various solvents, including chloroform, carbon tetrachloride, and toluene. The films were characterized by small angle X-ray scattering, UV and IR spectroscopy, ellipsometry, and atomic-force microscopy. The UV data and monolayer compression isotherms showed changes in the state of hydroxamic acid in various solvents in the presence of light and in the dark. The suggestion was made that changes in solutions were related to aggregation phenomenon. Original Russian Text ? T.A. Duda, L.L. Sveshnikova, V.K. Khlestkin, K.A. Dembo, L.G. Yanusova, 2009, published in Zhurnal Fizicheskoi Khimii, 2009, Vol. 83, No. 4, pp. 758–764.