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New unsaturated derivatives of the furan series, diallyl esters of furan-2,5-dicarboxylic acid and 5,5′-[oxybis(methylene)]di(2-furoic acid), which can be used as monomers and cross linking agents, were synthesized by the aerobic oxidation of 5-hydroxymethylfurfural and 5,5′-oxybis(5-methylene-2-furaldehyde) obtained by catalytic dehydration of fructose. Optimum conditions for the synthesis of the above-mentioned compounds and their copolymerization with butyl methacrylate were determined. Varying the amount of the cross-linking agent, the thermal stability, adhesion, strength and optical properties of copolymers can be controlled. New cross-linking agents obtained from renewable resources can be considered as an alternative to the important cross-linking agent, diallyl phthalate, produced from petroleum. [ABSTRACT FROM AUTHOR]

5-(Hydroxymethyl)furfural is readily oxidized to furan-2,5-dicarbaldehyde with sodium nitrite in phosphoric acid at room temperature (25°C). The best selectivity for furan-2,5-dicarbaldehyde is achieved using 2.5 equiv of sodium nitrite with respect to the substrate. In this case, nearly quantitative yield of furan- 2,5-dicarbaldehyde is attained in 1 h, the substrate conversion being complete. Due to high selectivity in combination with low cost and toxicity of phosphoric acid, the system NaNO2-H3PO4 is more convenient than NaNO2-CF3COOH for the preparative synthesis of furan-2,5-dicarbaldehyde. [ABSTRACT FROM AUTHOR]

Two improved methods for the synthesis of 5-hydroxymethylfurfural by acid-catalyzed dehydration of fructose have been developed. The first one is the synthesis in ionic liquids with continuous removal of water under reduced pressure, and the second is the synthesis in the two-phase system consisting of aqueous NaHSO and methyl isobutyl ketone under atmospheric pressure. Both methods ensure isolation of crystalline 5-hydroxymethylfurfural with high purity and multiple recycling of the catalytic system. The synthesis in ionic liquid is convenient on a laboratory scale. Despite relatively low yield, the two-phase synthesis is preferred for industrial scale-up due to simple isolation and purification procedures combined with efficient regeneration of extractant and the catalytic system. [ABSTRACT FROM AUTHOR]

Pyrolysis gases and condensates were analyzed for inorganic compounds and total sulfur in relation to the pyrolysis temperature, with the aim to improve a process for preparing granulated activated carbons from peat, polymer wastes, and sulfuric acid. [ABSTRACT FROM AUTHOR]

Dependences of the equilibrium adsorption capacity of FAS-Z, AG-3-O, and KAD-iodine activated carbons for iron at pH 1, 1.5, 2, and 3 in the presence of equimolar amounts of trivalent iron and disodium salt of acid in the starting aqueous solution were determined. [ABSTRACT FROM AUTHOR]

The composite materials based on a thermosetting binder mark SFP and thermally expanded graphite and containing 50–70% of the filler are prepared by the method of hot pressing. It is studied how the physicochemical and mechanical characteristics of the composite depend on the method of filler introduction. The materials prepared by mixing air-dry components are shown to exhibit the high conductivity (up to 195 S/cm) and strength (above 25 mPa), the low interface contact resistance (less than 10 mΩ cm2), and the corrosion current not exceeding 1 µA/cm2, which allows the high efficiency of energy conversion in SPFC to be reached. [ABSTRACT FROM AUTHOR]

For the purpose of evaluation of suitability of the Kalewa fossil coal deposit (Kalewa, Myanmar) for the production of granular active coals, the results of its petrographic analysis in the form of maceral composition and an arbitrary vitrinite reflection index are characterized, indicating the potential possibility of its use for solving this problem, based on the data of thermographic tests performed in a protective atmosphere, the rational limits of the thermal effect on this raw material during pyrolysis are estimated, the rational conditions of this process and the activation of its carbonized residue by water vapor are presented, the low efficiency of steam activation is shown, and the results are presented. The results of the chemical activation of the named fossil coal by alkaline agents in the form of NaOH and KOH, indicating the possibility of obtaining active coals with structural and adsorption properties acceptable for practical use, the conclusion is made that the processes need to be improved. [ABSTRACT FROM AUTHOR]

By-products formed in the conversion of vegetable biomass (multicomponent tar) were studied in comparison with the target products of the process (5-hydroxymethylfurfural, 2,5-diformylfuran) as inhibitors of corrosion of low-carbon steel in sulfuric acid at temperatures of 25-90°C. The gravimetric method was used to determine the inhibiting effect of additives. All these additives exhibit medium protective effects in an acid medium, with the degree of protection in 1 M sulfuric acid at room temperature exceeding 80%. The potentiody-namic polarization method was used to determine the influence exerted by the additives on partial reactions of the corrosion process. It was shown that the tar and 2,5-diformylfuran behave as additives of the cathodic type, and 5-hydroxymethylfurfural, as that of a mixed type. Temperature-kinetic calculations were used to determine the mechanism of action of the inhibitors. The corrosion process occurs in the presence of additives predominantly under the kinetic control. [ABSTRACT FROM AUTHOR]

The possibilities of fabrication and properties of new furan-containing polymers based on 5-hydroxymethylfurfural (5-HMF) and nitrogen-containing co-monomers (urea and melamine) have been studied. Two series of polymers, namely, 5-HMF-melamine and 5-HMF-urea at different ratios of the furan component: melamine (urea) were obtained. The effect of temperature in the range of 80–180 °C on the degree of cross-linking of polymers was studied. The thermostability of polymers was investigated by the TGA method. The polymers were tested for fire resistance according to GOST 28157-89 standard. It is demonstrated that obtained materials show increased heat and fire resistance in comparison to similar urea- and melamine-formaldehyde resins. It is recommended to use the developed polymers as non-combustible heat-insulating materials. [ABSTRACT FROM AUTHOR]

Effect of a number of modifying additives on the preparation and molding of raw mixtures in manufacture of coal-based granulated activated carbons of AG-90 brand is analyzed. [ABSTRACT FROM AUTHOR]

Quaternization of 2-hetarylimidazoles by the action of methyl iodide in anhydrous benzene was performed. The reaction involving 1-methyl-2-pyridyl-1 H-imidazoles was studied in detail. Relative rate of 2-hetarylimidazoles quaternization changes in parallel with their basicity. The alkylation of aza group was found to be very sensitive to steric factors. The methylation of 1-methyl-2-(3-pyridyl)-1 H- and 1-methyl-2-(4- pyridyl)-1 H-imidazoles was accompanied with the formation of isomeric quaternary imidazole and pyridine salts. [ABSTRACT FROM AUTHOR]