Valery E. Tarabanko

Kinetics of levulinic acid formation from carbohydrates at moderate temperatures

The kinetic curves of levulinic acid accumulation in the process of saccharide dehydration at 80-98oC are compared. The structural features of the substrates and 5-hydroxymethylfurfural, which is the intermediate of the process, explain the observed difference in the rates of fructose and glucose conversion. Sulfuric acid can be effectively used under moderate conditions to synthesize levulinic acid with yields exceeding 35 mol % for glucose and 50% for sucrose at 98oC.

Processing Pine Wood into Vanillin and Glucose by Sequential Catalytic Oxidation and Enzymatic Hydrolysis

Extractive-free pine wood was processed into vanillin (up to 18 wt.% of the initial lignin) and cellulose (typically 84–93% of the initial amount in the wood) by one-step catalytic oxidation followed by enzymatic hydrolysis of the resulting cellulose into glucose (reducing sugar yield up to 70% based on the post-oxidation cellulose). Correlation between the cellulose conversion in hydrolysis and the lignin content in the post-oxidation lignocellulosic material was established, which follows the general trend for the products of various delignification methods. The obtained results demonstrate the practical possibility of efficient two-step processing of wood into vanillin and glucose.

Antiknock properties of furfural derivatives

Preparative amounts of furfuryl alcohol ethers and furfural acetals were prepared from renewable vegetable raw materials. The blending reseach octane numbers of mixing of furan derivatives in straight-run gasoline were estimated: butyl furfuryl ether, 97.8 ± 7; propyl furfuryl ether, 112 ± 6; furfural diethyl acetal, 105 ± 6, furfural ethylene glycol acetal, 108 ± 7; furfurylamine, 194 ± 4. These results demonstrate prospects for using furan derivatives as available biofuels.

Catalytic Oxidation of Lignins into the Aromatic Aldehydes: General Process Trends and Development Prospects

This review discusses principal patterns that govern the processes of lignins’ catalytic oxidation into vanillin (3-methoxy-4-hydroxybenzaldehyde) and syringaldehyde (3,5-dimethoxy-4-hydroxybenzaldehyde). It examines the influence of lignin and oxidant nature, temperature, mass transfer, and of other factors on the yield of the aldehydes and the process selectivity. The review reveals that properly organized processes of catalytic oxidation of various lignins are only insignificantly (10–15%) inferior to oxidation by nitrobenzene in terms of yield and selectivity in vanillin and syringaldehyde. Very high consumption of oxygen (and consequentially, of alkali) in the process—over 10 mol per mol of obtained vanillin—is highlighted as an unresolved and unexplored problem: scientific literature reveals almost no studies devoted to the possibilities of decreasing the consumption of oxygen and alkali. Different hypotheses about the mechanism of lignin oxidation into the aromatic aldehydes are discussed, and the mechanism comprising the steps of single-electron oxidation of phenolate anions, and ending with retroaldol reaction of a substituted coniferyl aldehyde was pointed out as the most convincing one. The possibility and development prospects of single-stage oxidative processing of wood into the aromatic aldehydes and cellulose are analyzed.

Thermodynamics of α-angelicalactone polymerization

Abstract Thermodynamics of sodium butoxide-catalyzed polymerization of α-angelicalactone (a five-member unsaturated lactone) is studied by calorimetric methods. A polymer with Mw = 2,500 g/mol and the ratio of C–O to C–C inter-monomeric bonds 87–13% is obtained; this polymerization is characterized by the values of = −33.41 kJ/mol, = −42.69 J/(mol∙K) and = −20.68 kJ/mol. This and similar polymers and copolymers are biodegradable and can be produced from commercially available green bio-platform feedstock: renewable carbohydrates and levulinic acid.

Synthesis of a Polyconjugated Polymer by Aldol Condensation of 2,5-Diformylfuran and Acetone

Pioneer synthesis of the product of aldol polycondensation between 2,5-diformylfuran and acetone is presented. The synthesis was accomplished by a direct reaction of diformylfuran and acetone in dimethyl sulfoxide with addition of aqueous sodium hydroxide as a catalyst. The fact of the aldol condensation occurrence and formation of the polyconjugated oligomers in this system is confirmed by 1H nuclear magnetic resonance and molecular absorption spectroscopy. Cannizzaro reaction plays a significant side process role in the studied system, leading to the loss of diformylfuran’s aldehyde groups and their inability to participate in polymer chain growth. A solid polymeric product of brown color was isolated with the yield of 28 % based on the initial diformylfuran. The solid product is insoluble (judging by the lack of coloration in liquid) in various tested solvents: water, 1,4-dioxane, dimethyl sulfoxide, acetone, chloroform, or 1,2-dichloroethane with trifluoroacetic acid mixed in different proportions. The presence of polyconjugated chains in the solid product is confirmed by electron spin resonance spectroscopy.

Synthesis of Copolymers of Furandicarboxylic Acid, Ethylene Glycol, and Poly(Angelica Lactone)

This work demonstrates the possibility of creating biodegradable derivatives of poly(ethylene furandicarboxylate) by modification with poly(angelica lactone) chains. Block copolymers with the content of angelica lactone 33-50 mol. % (based on monomeric links) were obtained. Polymer yields were 60-70 %, and weight average molecular weights attained 36-45 kDa. The results of the polymers biodegradation are presented.

Interaction of Titanium (IV) Chloride Vapor with Cotton Cellulose and Catalytic Properties of the Titanium Dioxide Obtained

The slow (8-10 days) interaction of TiCl4 vapors and dry cotton cellulose has been studied. The process is compared to the liquid phase one. In both cases titanium oxychlorides are mainely formed on the surface of the cellulose fibers at room temperature. Heating of such fibers in air at 500 oC produces long anatase titania deformed hollow fibers consisted of fine films of 100-200 nm thickness. The BET surface of the fibers is of 25.6 m2/g including micropores surface of 5.3 m2/g, and a pore volume of diameter less then 451 nm is of 0.078 cm3/g. The efficient photocatalytic oxidation of methylene blue over synthesized titania fibers is demonstrated.

Synthesis and Anti-Knock Properties of Furfural Derivatives

Research octane numbers (RON) of the furfural diethyl acetal and furfurylamine solutions in straight-run gasoline were measured, and the liner dependences between the solution octane numbers and concentrations of furfural derivatives were found. Blending research octane numbers (BRON) for furfural diethyl acetal (106.0±3.8) and furfurylamine (193.5±7.7) are calculated. A novel method of syntheses of furfural diethylacetal by the direct interaction of the alcohol and the aldehyde is developed. To shift the reaction equilibrium a water vapour from gas phase over the reaction mass is removed by calcium oxide. Oxidative stability of the furfurylamine solutions in straight-run gasoline (test for induction period) was estimated. It corresponds to the GOST 2084-77 conditions at the furfurylamine concentrations less than 5 wt. % and exceeds value of 1000 min.