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A synthetic method for betulin 3-O-propionate 28-O-acylates via the reaction of betulin 3-O-propionate with melts of benzoic, phthalic, cinnamic, and succinic acids at 185–195°C for 5–6 min was proposed. [ABSTRACT FROM AUTHOR]

Many natural polysaccharides have biological activity, which allows them to be used for obtaining medicines. Development of new methods for the isolation of polysaccharides from plant materials, as well as investigation of their properties and structure constitute a topical task. In this study, polysaccharide galactoglucomannan (GGM) was isolated from pine wood for the first time by the peroxide delignification in the acetic acid-water medium in the presence of (NH4)6Mo7O24 catalyst. The GGM yield was 10.1 wt % of the wood sample and 58.1 wt % of the hemicelluloses content in the wood. Using 13C NMR method it was found that the degree of GGM acetylation was 0.23 with substitution at C2 and C3 atoms of the pyranose ring. According to the X-ray phase analysis data, GGM has an amorphous supramolecular structure. Polysaccharide glucoxylan (GX) was isolated by alkaline extraction from the cellulosic product of the peroxide delignification in a yield of 4.3 wt % of the wood sample and of 24.5 wt % of the hemicelluloses content in the wood. Glucoxylan does not contain acetyl groups (IR and NMR spectroscopy data); it has a crystalline supramolecular structure and is poorly soluble in water. The composition and structure of the isolated polysaccharides were studied by chemical analysis methods, as well as by IR spectroscopy, 1H, 13C, 2D HSQC NMR spectroscopy, gas chromatography, and X-ray phase analysis. [ABSTRACT FROM AUTHOR]

Synthetic methods for betulin 3-acetate-28-benzoate, betulin 3-acetate-28-p-bromobenzoate, betulin 3-acetate-28-cinnamate, betulin 3-acetate-28-succinate, and betulin 3-caetate-28-phthalate based on the reaction of betulin 3-acetate with fused benzoic, p-bromobenzoic, cinnamic, succinic, and phthalic acids at 185–195°C for 5–6 min are proposed for the first time. [ABSTRACT FROM AUTHOR]

For the first time, it is proposed to combine the environmentally friendly heterogeneous catalytic processes of wood hemicelluloses hydrolysis and peroxide delignification of «hemicellulose-free» wood for the biorefinery of birch wood into microcrystalline, microfibrillated, and nanocrystalline celluloses, xylose, and sorbents. The use of the solid acid catalyst ZrO2/SO42− for the hydrolysis of birch-wood hemicelluloses at a temperature of 150 °C makes it possible to obtain xylose with a yield of 72.5% from the weight of hemicelluloses. The optimal conditions for peroxide delignification of «hemicellulose-free» birch wood in a «formic acid–water» medium over TiO2 catalyst, which ensure a high yield of microcrystalline cellulose (41.2% from weight of wood), were established. By sulfuric acid hydrolysis and ultrasonic treatment of microcrystalline cellulose, samples of microfibrillated and nanocrystalline celluloses were produced. Adsorbents with high sorption activity were obtained from organosolv lignin formed as a side product of peroxide delignification of birch lignocellulose. The birch biorefinery products were characterized by Fourier transform infrared spectroscopy, X-ray diffractometry, scanning electron microscopy, gel permeation chromatography, 31P nuclear magnetic resonance, dynamic light scattering, as well as chemical and elemental analysis. [ABSTRACT FROM AUTHOR]

The main components of the birch wood were fractionated into a microcrystalline cellulose, xylose and enterosorbents by an integration of heterogeneous catalytic processes of an acidic hydrolysis and a peroxide delignification of the wood biomass for the first time. The wood hemicelluloses were hydrolyzed to xylose at a temperature of 150°C in the presence of the Amberlyst® 15 solid acidic catalyst. Then, the lignocellulosic product of the wood hydrolysis was subjected to the peroxide delignification in the formic acid–water medium in the presence of the solid TiO2 catalyst with a formation of the microcrystalline cellulose (MCC) and the organic-soluble lignin. Yields of MCC and the organic-soluble lignin proved to be 64.5 and 11.5 wt % of a mass of the prehydrolyzed wood, respectively, under the determined optimal conditions (100°C, 7.2 wt % of Н2О2, 37.8 wt % of НСООН, LWR 15, and a duration of 4 h). The enterosorbents were prepared by a treatment of the organic-soluble lignin with 0.4% NaHCO3 or hot water. The sorption capacity of these enterosorbents was 97.7 and 236.7 mg/g according to methylene blue and gelatin, respectively. These values were significantly higher than those of the Polifepan commercial enterosorbent (44 and 115 mg/g, respectively). The products of the catalytic fractionation of the birch wood were characterized by physicochemical (FTIR, XRD, SEM, and GC) and chemical methods. [ABSTRACT FROM AUTHOR]

Experiments and calculations are used to determine the optimum parameters of the peroxide delignification of larch wood in the presence of MnSO4 catalyst that provides high yields of cellulose (44.3 wt %) with low residual lignin contents at a temperature of 100°C, an H2O2 content of 6 wt %, a CH3COOH content of 25 wt %, a LWR of 15, and a duration of 3 h The cellulose obtained under optimum conditions has a chemical composition of cellulose, 92.7 wt %; lignin, 0.6 wt %; and hemicellulose, 5.7 wt %. IRS and X-ray diffraction are used to determine that cellulose obtained from larch wood has a structure similar to that of industrial microcrystalline cellulose. The proposed catalytic approach allows cellulose to be obtained from larch wood with a minimal lignin content under mild conditions in one step and with a high yield, a degree of crystallinity of 0.8, and a crystallite size of 3.0 nm. [ABSTRACT FROM AUTHOR]

A kinetic study and optimization of pine wood peroxide fractionation in the medium acetic acid–water over TiO2 catalyst were accomplished for the first time. Kinetic regularities and the product composition of green processes of catalytic peroxide fractionation of softwood (pine, abies, larch) and hardwood (aspen, birch) over 1 wt% TiO2 catalyst in the acetic acid–water medium were compared at the temperature range 70–100 °C. For all type of wood, the processes of peroxide delignification are described by the first order equations and their activation energies are varied at the range 76–94 kJ/mol. According to FTIR, XRD, SEM, NMR data, the cellulosic products of peroxide delignification have a structure similar to microcrystalline cellulose regardless of the nature of wood. Soluble products are presented by organic acid and monosaccharides. The scheme of green biorefinery of pine wood based on extractive-catalytic fractionation of wood biomass on microcrystalline cellulose, hemicelluloses, aromatic and aliphatic acids, monosaccharides, turpentine and rosin was developed. Green and non-toxic reagents and solid catalyst are used in the developed scheme of biorefinery. [ABSTRACT FROM AUTHOR]

Abstract: The conventional way of producing microcrystalline cellulose (MCC) from wood raw materials is multistage; it is based on integrating the environmentally hazardous processes of pulping and bleaching of cellulose and the acid hydrolysis of the amorphous phase of cellulose. This work describes an improved single-stage catalytic method for the production of MCC from softwood and hardwood that is based on the peroxide delignification of wood in an acetic acid-water medium under mild conditions (100°C, atmospheric pressure) in the presence of an environmentally safe TiO2 solid catalyst. The processes of MCC production via the peroxide catalytic delignification of various wood species are optimized experimentally and mathematically. The following optimum modes for the production of MCC with a yield of 36.3-42.0 wt % of absolutely dry wood, a residual lignin content of ≤1.0 wt %, and a hemicellulose content of ≤ 6.0 wt % are determined: For aspen: 5 wt % H2O2, 25 wt % CH3COOH, and a liquid/wood ratio of 10. For birch: 5 wt % H2O2, 25 wt % CH3COOH, and a liquid/wood ratio of 15. For silver fir: 6 wt % H2O2, 30 wt % CH3COOH, and a liquid/wood ratio of 15. For larch: 6 wt % H2O2, 30 wt % CH3COOH, and a liquid/wood ratio of 15. [ABSTRACT FROM AUTHOR]

The first green biorefinery of larch wood based on the fractionation of biomass into dihydroquercetin (DHQ), arabinogalactan (AG), microcrystalline cellulose (MCC) and soluble lignin (SL) is reported. The new green method of one-step isolation of DHQ and AG from larch wood by ethanol-water solution was developed. The first results of kinetic studies and optimization of the process of extracted larch wood peroxide fractionation into MCC and SL in acetic acid-water medium in the presence of green TiO2 catalyst are described. The products obtained from larch wood were characterized by FTIR, NMR, XRD, AFM and chemical methods. The scheme of larch wood biorefinery is suggested which integrates the developed processes of woody biomass fractionation into DHQ, AG, MCC and SL. All developed methods use non-toxic and less-toxic reagents, such as water, ethanol, hydrogen peroxide and acetic acid. [ABSTRACT FROM AUTHOR]

It is established that the main regularities of the peroxide delignification of aspen wood in the temperature range of 70–100°С in the presence of dissolved (H2SO4) and solid (TiO2) catalysts are similar. With an increase of the temperature, the concentration of hydrogen peroxide and acetic acid, and the hydromodule (HM) values, as well as the duration of the process and the content of cellulose in the cellulose products, increase, while the content of the residual lignin decreases. Simultaneously, the total yield of cellulose products decreases independently of the nature of the catalyst. Delignification processes are satisfactory described by the first-order equation. A sufficiently high activation energy (88 kJ/mol in the presence of H2SO4 and 75 kJ/mol in the presence of TiO2) indicates the absence of significant external diffusion constraints in the selected conditions. The optimal conditions of obtaining cellulose products with a low content of residual lignin from aspen wood are found by the calculation methods. It is shown by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM) that the structure of cellulose products obtained corresponds to the structure of industrial microcrystalline cellulose. In the optimal conditions, a high-quality cellulose product can be obtained in mild conditions (the temperature is 100°С, atmospheric pressure) by using a safer and technological TiO2 catalyst instead of a sulfuric acid catalyst. [ABSTRACT FROM AUTHOR]

The process of aspen-wood delignification in the medium “hydrogen peroxide–acetic acid–water–sulfuric acid catalysts” at mild conditions (temperature 70–100 °C, atmospheric pressure) is described by the first order equation. Rate constants vary from 0.25 × 10 −4 (70 °C) to 2.5 × 10 −4 s −1 (100 °C). The activation energy of aspen-wood delignification is near 91 kJ mol −1. The rather high value of activation energy points to the insignificant role of diffusion limitations at used conditions of aspen-wood delignification. The optimal process conditions for obtaining of the pure cellulose (residual lignin content less 1 wt%) with a yield near 45 wt% were selected. Obtained cellulose has the structure similar to the commercial microcrystalline cellulose. [ABSTRACT FROM AUTHOR]