Determination of standard isotherms of the sorption of some vapors with cellulose

Standard isotherms of the sorption of water, methanol, and benzene vapors on cellulose using a cellulose standard are determined. The standard, namely, mesoporous cellulose with specific surface of up to 350 m2/g, is obtained by the method of exchanging water in swollen cellulose with organic solvents. A comparison of the experimental sorption isotherm with the standard isotherm makes it possible to determine the specific surface of celluloses accessible a the given sorbate and, in combination with the Brunauer-Emmett-Teller adsorption equation, to characterize their surface properties. The identity of the sorption properties of the initial and dewatered (porous) celluloses relative to active vapors is shown, which evidences the assumed mechanism of swelling as the sorbent's division into morphological structures with the formation of new surface. A comparative analysis of the sorption properties of cellulose and silica, whose nature of active sorption centers is similar (weak acid hydroxyl groups), has been made. The affinity of the standard isotherms and close values of the cross-sectional area of different sorbates on both sorbents testify the similarity in their sorption behavior. Thus, the processes of sorption with rigid and swelling sorbents can be regarded in a unified context. Therefore, the adsorption models developed for rigid sorbents can be applied to cellulose sorbents to analyze their sorption properties.     

Hydrodynamic Conformation Properties of Poly(1-Trimethylsilylpropyne) Molecules Obtained on NbCl5 Catalyst

Hydrodynamic properties of 10 samples of poly(1-trimethylsilylpropyne) of various molecular weights, obtained with NbCl₅ catalyst and containing 60-70% cis C = C bonds, were studied by sedimentation, translation diffusion, and viscometry techniques. The equilibrium rigidity of the polymer molecules was estimated from the viscometric data using the formalism of the intrinsic viscosity theory as applied to the worm-like coil model with excluded-volume effects. For the polymer macromolecules, the Kuhn segment length, thermodynamic parameter , and hydrodynamic diameter of the chain d were estimated.     

Labdane and cembrane diterpenoids from the oleoresin of thePicea ajanensis

From the oleoresin of the Yeddo spruce (Picea ajanensis Fisch.) have been isolated cis-abienol, isocembrol, geranyllinalool, epimanool, and labd-13E-ene-8,15-diol. It has been established that the biosynthesis of isocembrol and epimanool in the Yeddo spruce is not accompanied by the formation of epimers of these compounds — 4-epiisocembrol and manool — and that cis-abienol is the main neutral oxygen-containing compound of the oleoresin investigated in terms of content.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 178–181, March–April, 1981.     

Synthesis of Functional Derivatives of Benzofuran-5,6-dicarboxylic Acids

Russian Journal of General Chemistry - Synthetic routes to novel substituted benzofuran-5,6-dicarboxylic acids and furo[2,3-f]isoindole-5,7-diones via acid hydrolysis of the corresponding...     

Synthesis of substituted pyrazolo[1,5-a]quinoxalines using the reductive cyclization

Russian Chemical Bulletin - New pyrazolo[1,5-a]quinoxalin-4-ones were obtained by reductive cyclization from the corresponding 1-(2-nitroaryl)pyrazole-5-carboxylates. Alternatively,...     

Formylation of indol-1-yl acetates

Preparation procedure was developed for 3-formylindole-5,6-dicarbonitriles underlain by the treatment of 1-acetoxyindole-5,6-dicarbonitriles with Vilsmeier-Haack reagent; a special feature of this reaction consisted in a replacement of the OAc group for hydrogen. A probable mechanism was assumed of the formation of 3-formylindole-5,6-dicarbonitriles.     

Synthesis of Substituted 2-Oxo-2,3-dihydro-1H-imidazo-[1,2-a]indole-6,7-dicarbonitriles

A three-step procedure has been developed for the synthesis of 2-oxo-2,3-dihydro-1H-imidazo-[1,2-a]indole-6,7-dicarbonitriles from substituted 2-amino-1-hydroxy-1H-indole-5,6-dicarbonitriles.

     

Мicro-Optical Structures Written by Photothermal Method in a Specially Modified Near-Surface Layer of Lithium Niobate Crystals

Russian Physics Journal -     

The Influence of Submicron Particles of Coal Concentrate on the Conditions of Aerosol Synthesis of Carbon Nanotubes

Russian Physics Journal -     

Chemical modification of poly(vinyltrimethylsilane) and poly(1-trimethylsilyl-1-propyne) using highly reactive metallating systems

Poly(vinyltrimethylsilane) and poly(1-trimethylsilyl-1-propyne) are metallated using normal and secondary butyllithium chelate complexes with tetramethylethylenediamine and superbases based on complexes of normal and secondary butyllithium with potassium tert-pentoxide as metallating agents. Optimal conditions ensuring metallation of poly(vinyltrimethylsilane) and poly(1-trimethylsilyl-1-propyne) with a high yield without degradation of macrochains are determined. Poly(vinyltrimethylsilane) and poly(1-trimethylsilyl-1-propyne) are functionalized via reactions of metallated polymers with CO₂, trimethylsilyl chlorosulfone, diethyl disulfide, and ethylene oxide. COOH, SO₃H, OH, and thioester groups are introduced into poly(vinyltrimethylsilane), and SO₃H and COOH groups are incorporated into poly(1-trimethylsilyl-1-propyne). Upon introduction of carboxyl groups into poly(vinyltrimethylsilane), its hydrophilicity and permselectivity with respect to H₂O/N₂, H₂O/H₂, and H₂O/CH₄ pairs increase. The introduction of SO₃H groups into poly(1-trimethylsilyl-1-propyne) and poly(vinyltrimethylsilane) leads to the appearance of proton conductivity of these polymers.