New Azo Derivatives of Ethanol Lignin: Synthesis, Structure, and Photosensitive Properties

Water-soluble azo derivatives of lignin were synthesized by the azo coupling reaction using organosolv ethanol lignin and diazonium salts based on sulfanilic acid and p-nitroaniline. The structure of azo derivatives of lignin were studied by nuclear magnetic resonance, Fourier-transform infrared spectroscopy, and gel permeation chromatography. It was found that the azobenzene bonds formed in the azo coupling reaction of macromolecules impart the photosensitive properties to the synthesized polymers via cis–trans photoisomerization of the diazobenzene group. It was shown experimentally that the synthesized polymers exhibited good solubility both in the aqueous media in a wide (2–12) pH range and in DMSO and THF organic solvents, which opens up new prospects for their application

Modification of Arabinogalactan Isolated from Larix sibirica Ledeb. into Sulfated Derivatives with the Controlled Molecular Weights

The process of sulfation of arabinogalactan—a natural polysaccharide from Larix sibirica Ledeb.—with sulfamic acid in 1,4-dioxane using different activators has been studied for the first time. The dynamics of the molecular weight of sulfated arabinogalactan upon variation in the temperature and time of sulfation of arabinogalactan with sulfamic acid in 1,4-dioxane has been investigated. It has been found that, as the sulfation time increases from 10 to 90 min, the molecular weights of the reaction products grow due to the introduction of sulfate groups without significant destruction of the initial polymer and sulfation products. Sulfation at 95 °C for 20 min yields the products with a higher molecular weight than in the case of sulfation at 85 °C, which is related to an increase in the sulfation rate; however, during the further process occurring under these conditions, sulfation is accompanied by the destruction and the molecular weight of the sulfated polymer decreases. The numerical optimization of arabinogalactan sulfation process has been performed. It has been shown that the optimal parameters for obtaining a product with a high sulfur content are a sulfamic acid amount of 20 mmol per 1 g of arabinogalactan, a process temperature of 85 °C, and a process time of 2.5 h

Influence Different Methods of Mechanical Activation on Yield Extractive Substances from Pine Bark

Исследовано влияние активации коры сосны взрывным автогидролизом и механической обработкой в барабанной мельнице на выход и свойства смолистых и пектиновых веществ и β-ситостерин. Изучены физико-химические свойства коры сосны после ее активации различными способами. Показано, что активация коры сосны взрывным автогидролизом приводит к наибольшему увеличению выхода экстрактивных веществ. Определены условия, обеспечивающие наибольший выход целевых продуктов из активированной коры сосны: для смолистых веществ и β-ситостерина – применение 0.5 н раствора щелочи; для пектиновых веществ – использование соляной кислотыThe effect pine bark activation by explosive autohydrolysis and mechanical treatment in a ball mill on the yield and properties of resinous and pectin substances and β-sitosterol was studied. Pine bark physicochemical properties after its activation by a batch of methods were studied. It was shown that the activation of pine bark by explosive autohydrolysis result in the highest increase in the yield of extractive substances. The conditions providing the highest yield of target products from the activated pine bark were determined: for resinous substances and β-sitosterol – the use of 0.5 n alkali solution; for pectin substances – the use of hydrochloric aci

Comprehensive Study of the Ammonium Sulfamate–Urea Binary System

The physicochemical properties of binary systems are of great importance for the application of the latter. We report on the investigation of an ammonium sulfamate–urea binary system with different component ratios using a combination of experimental (FTIR, XRD, TGA/DSC, and melting point) and theoretical (DFT, QTAIM, ELF, RDG, ADMP, etc.) techniques. It is shown that, at a temperature of 100 °C, the system under study remains thermally and chemically stable for up to 30 min. It was established using X-ray diffraction analysis that the heating time barely affects the X-ray characteristics of the system. Data on the aggregate states in specified temperature ranges were obtained with thermal analysis and determination of the melting point. The structures of the ammonium sulfamate–urea system with different component ratios were optimized within the density functional theory. The atom-centered density matrix propagation calculation of the ammonium sulfamate–urea system with different component ratios was performed at temperatures of 100, 300, and 500 K. Regardless of the component ratio, a regular increase in the potential energy variation (curve amplitude) with an increase in temperature from 100 to 500 K was found

Molecular Characteristics and Antioxidant Activity of Spruce (<i>Picea abies</i>) Hemicelluloses Isolated by Catalytic Oxidative Delignification

Spruce (Piceaabies) wood hemicelluloses have been obtained by the noncatalytic and catalytic oxidative delignification in the acetic acid-water-hydrogen peroxide medium in a processing time of 3–4 h and temperatures of 90–100 °C. In the catalytic process, the H2SO4, MnSO4, TiO2, and (NH4)6Mo7O24 catalysts have been used. A polysaccharide yield of up to 11.7 wt% has been found. The hemicellulose composition and structure have been studied by a complex of physicochemical methods, including gas and gel permeation chromatography, Fourier-transform infrared spectroscopy, and thermogravimetric analysis. The galactose:mannose:glucose:arabinose:xylose monomeric units in a ratio of 5:3:2:1:1 have been identified in the hemicelluloses by gas chromatography. Using gel permeation chromatography, the weight average molar mass Mw of hemicelluloses has been found to attain 47,654 g/mol in noncatalytic delignification and up to 42,793 g/mol in catalytic delignification. Based on the same technique, a method for determining the α and k parameters of the Mark–Kuhn–Houwink equation for hemicelluloses has been developed; it has been established that these parameters change between 0.33–1.01 and 1.57–472.17, respectively, depending on the catalyst concentration and process temperature and time. Moreover, the FTIR spectra of the hemicellulose samples contain all the bands characteristic of heteropolysaccharides, specifically, 1069 cm−1 (C–O–C and C–O–H), 1738 cm−1 (ester C=O), 1375 cm−1 (–C–CH3), 1243 cm−1 (–C–O–), etc. It has been determined by the thermogravimetric analysis that the hemicelluloses isolated from spruce wood are resistant to heating to temperatures of up to ~100 °C and, upon further heating, start destructing at an increasing rate. The antioxidant activity of the hemicelluloses has been examined using the compounds simulating the 2,2-diphenyl-2-picrylhydrazyl free radicals

Composition and Structure of Aspen (P&oacute;pulus tr&eacute;mula) Hemicelluloses Obtained by Oxidative Delignification

In this study, hemicelluloses of aspen wood (P&oacute;pulus tr&eacute;mula) were obtained by oxidative delignification in an acetic acid-water-hydrogen peroxide medium at temperatures of 70&ndash;100 &deg;C and a process time of 1&ndash;4 h. The maximum polysaccharide yield of up to 9.68 wt% was reported. The composition and structure of the hemicelluloses were studied using a complex of physicochemical methods: gas and gel permeation chromatography, Fourier-transform infrared spectroscopy, 2D nuclear magnetic resonance spectroscopy, and thermogravimetric analysis. The xylose, mannose, galactose, and glucose monomer units were identified in the hemicelluloses by gas chromatography. The weight average molecular weight Mw of the products determined by gel permeation chromatography was found to range within 8932&ndash;33,142 g/mol. The reported Fourier-transform spectra of the hemicelluloses contain all the bands characteristic of heteropolysaccharides; a weak lignin absorption signal in the spectra at 1500&ndash;1510 cm&minus;1 is attributed to a minor content of phenolic fragments in the structure of the obtained hemicelluloses. The use of thermogravimetric analysis established that the hemicelluloses isolated from aspen wood are resistant against heating to temperatures of up to 90&ndash;100 &deg;C and, upon further heating up to 400 &deg;C, start destructing at an increasing rate. The antioxidant activity of the hemicelluloses was examined using the compounds that mimic free radicals (1,1-diphenyl-2-picrylhydrazyl) and hydroxyl radicals (salicylic acid). It was found that the activity of all polysaccharides in neutralizing DPPH and hydroxyl radicals is lower than the absorption capacity of vitamin C at all the tested concentrations (0.5, 2, and 5 mg/mL) and attains 81.7 and 82.9%, respectively

Food Xanthan Polysaccharide Sulfation Process with Sulfamic Acid

Xanthan is an important polysaccharide with many beneficial properties. Sulfated xanthan derivatives have anticoagulant and antithrombotic activity. This work proposes a new method for the synthesis of xanthan sulfates using sulfamic acid. Various N-substituted ureas have been investigated as process activators. It was found that urea has the greatest activating ability. BBD of xanthan sulfation process with sulfamic acid in 1,4-dioxane has been carried out. It was shown that the optimal conditions for the sulfation of xanthan (13.1 wt% sulfur content) are: the amount of sulfating complex per 1 g of xanthan is 3.5 mmol, temperature 90 °C, duration 2.3 h. Sulfated xanthan with the maximum sulfur content was analyzed by physicochemical methods. Thus, in the FTIR spectrum of xanthan sulfate, in comparison with the initial xanthanum, absorption bands appear at 1247 cm−1, which corresponds to the vibrations of the sulfate group. It was shown by GPC chromatography that the starting xanthan gum has a bimodal molecular weight distribution of particles, including a high molecular weight fraction with Mw &gt; 1000 kDa and an LMW fraction with Mw &lt; 600 kDa. It was found that the Mw of sulfated xanthan gum has a lower value (~612 kDa) in comparison with the original xanthan gum, and a narrower molecular weight distribution and is characterized by lower PD values. It was shown by thermal analysis that the main decomposition of xanthan sulfate, in contrast to the initial xanthan, occurs in two stages. The DTG curve has two pronounced peaks, with maxima at 226 and 286 °C

Экспериментальная и математическая оптимизация процесса выделения β-ситостерина из механически активированной коры сосны

The optimization of the process of β-sitosterol extraction from the original and activated with two different methods (drum mill, explosive autohydrolysis) pine bark was carried out. The effect of the duration of the extraction process and the concentration of NaOH in the saponification solution on the yield of β-sitosterol was explored. The concentration of NaOH in the saponification solution appeared to have the highest effect on the β-sitosterol yields from activated pine bark. Mechanical activation of pine bark significantly increased the yield of β-sitosterol and reduced the duration of the isolation process. The highest yield of β-sitosterol was achieved with the use of pine bark activated by explosive autohydrolysis. According to the proposed mathematical model, the maximum predicted value of the β-sitosterol yield from this sample is 0.078 (wt%). This could be achieved using the process duration 10.3 hours and a 0.5 N solution of NaOH. This yield is close to the content of β-sitosterol in the original pine barkВ работе проведена оптимизация процесса выделения β-ситостерина из исходной и предварительно активированной двумя способами (барабанная мельница, взрывной автогидролиз) коры сосны. Установлено влияние продолжительности процесса и концентрации NaOH в омыляющем растворе на выход β-ситостерина. Показано, что при использовании предварительно активированной коры сосны наибольшее влияние на процесс выделения β-ситостерина оказывает концентрация NaOH в омыляющем растворе. Механическая активация коры сосны позволяет существенно увеличить выход β-ситостерина и уменьшить продолжительность процесса его выделения. Наибольший выход β-ситостерина достигается при использовании коры сосны, предварительно активированной взрывным автогидролизом. Согласно полученной математической модели максимальное значение выхода β-ситостерина из этого образца коры составляет 0,078 мас.%, что достигается при продолжительности процесса 10,3 ч и использовании 0,5 н NaOH. Этот выход близок к содержанию β-ситостерина в исходной коре сосн