scholarly journals MATHEMATICAL OPTIMIZATION OF THE PROCESS OF BIRCH WOOD XYLAN SULFATION BY SULFAMIC ACID IN N, N-DIMETHYLFORMAMIDE MEDIUM

2021 ◽  
pp. 87-94
Author(s):  
Aleksandr Sergeyevich Kazachenko ◽  
Vladimir Aleksandrovich Levdansky ◽  
Aleksandr Vladimirovich Levdansky ◽  
Boris Nikolayevich Kuznetsov
Keyword(s):  
Nmr Spectroscopy ◽  
Mathematical Optimization ◽  
Sulfamic Acid ◽  
13C Nmr Spectroscopy ◽  
Sulphur Content ◽  
Effect Of Temperature ◽  
High Yield ◽  
Birch Wood ◽  
Optimal Conditions ◽  
Birch Wood Xylan

The effect of temperature and duration of sulfation of birch wood xylan by sulfamic acid in N, N-dimethylformamide (DMF) medium in the presence of urea on the yield of sulfated xylan and on the sulphur content was studied. By mathematical optimization, the sulfation conditions have been established allowing to achieve a high yield of the obtained xylan sulfates with a high sulphur content. Under optimal sulfation conditions: temperature 100±3 °C, duration 1.5 hours, the yield of sulfated xylan reaches to 63% mas. and the content of sulfur – 17.6% mas. The presence of sulfate groups in sulfated xylan samples obtained under optimal conditions was confirmed by elemental analysis and FTIR and 13C NMR spectroscopy.

scholarly journals Sylfation of Birch Wood Xylan with Sulfamic Acid in 1,4-dioxane

2021 ◽  
Vol 14 (3) ◽  
pp. 325-336
Author(s):  
Vladimir A. Levdansky ◽  
◽  
Alexander A. Kondrasenko ◽  
Alexander V. Levdansky ◽  
Boris N. Kuznetsov
Keyword(s):  
Nmr Spectroscopy ◽  
Sulfur Content ◽  
Sulfamic Acid ◽  
Birch Wood ◽  
Birch Wood Xylan ◽  
First Time

Sulfation of birch wood xylan in 1,4-dioxane by sulfamic acid in the presence of urea at 90 and 100 °C was studied for the first time. The effect of the duration of xylan sulfation on the yield of xylan sulfates and the sulfur content in them was studied. It was found that the sulfur content in the obtained xylan sulfates increases from 12.5 to 17.5 wt% with an increase in the duration of sulfation from 2 to 4 hours. The structure of initial and sulfated xylan was studied by FTIR and NMR spectroscopy. The ease of purification of the obtained xylan sulfates from 1,4-dioxane in comparison with the purification of xylan sulfates obtained by sulfation in pyridine and N, N‑dimethylformamide is an advantage of the proposed method of xylan sulfation

Experimental and mathematical optimization of the peroxide delignification of larch in the presence of MnSO4 catalyst

2020 ◽  
Vol 20 (1) ◽  
pp. 67-75
Author(s):  
I. G. Sudakova ◽  
N. V. Garyntseva ◽  
A. I. Chudina ◽  
B. N. Kuznetsov
Keyword(s):  
Mathematical Optimization ◽  
Single Step ◽  
High Yield ◽  
Optimal Conditions ◽  
Optimal Parameters ◽  
Mathematical Methods ◽  
Catalytic Method ◽  
Mild Conditions ◽  
Xrd Studies ◽  
Peroxide Delignification

Experimental and mathematical methods were used to obtain the optimal parameters of peroxide delignification of larch in the presence of MnSO4 catalyst, which provide a high yield of cellulose (44.3 wt.%) with a low content of residual lignin: temperature 100 °C, content of H2O2 6 wt.%, CH3COOH 25 wt.%, hydromodulus 15, and duration 3 h. The cellulose produced under optimal conditions had the following chemical composition: cellulose 92.7 wt.%, lignin 0.6 wt.%, and hemicellulose 5.7 wt.%. IR spectroscopy and XRD studies revealed that the structure of cellulose produced from larch is similar to that of industrial microcrystalline cellulose. The proposed catalytic method allows obtaining larch-derived cellulose with a minimum content of lignin under mild conditions in a single step with a high yield, crystallinity 0.8 and crystallite size 3.0 nm.

scholarly journals Isolation and Study of Abies Bark Proanthocyanidins

2019 ◽  
pp. 604-613
Author(s):  
Vladimir A. Levdansky ◽  
Alexander A. Kondrasenko ◽  
Alexander V.; Levdansky ◽  
Maxim A. Lutoshkin
Keyword(s):  
Nmr Spectroscopy ◽  
Hydrochloric Acid ◽  
13C Nmr ◽  
Maximum Yield ◽  
13C Nmr Spectroscopy ◽  
Optimal Conditions ◽  
Ethanol Medium ◽  
First Time ◽  
Water Alcohol Solutions ◽  
Water Alcohol

The process of proanthocyanidins isolation from abies bark by water and water-alcohol solutions containing 5, 10, 15 and 20 % ethanol was studied for the first time. The optimal conditions providing the maximum yield of proanthocyanidins were determined experimentally. It was shown that the use of 15-20 % water-alcohol solutions allows to increase the yield of proanthocyanidins from 0.33 to 0.38 %. The composition of the obtained proanthocyanidins was studied by UV, IR, and 13C NMR spectroscopy. The obtained proanthocyanidins were transformed into colored anthocyanidins in ethanol medium in the presence of hydrochloric acid. The flavonoids cyanidin and delphinidin were isolated and identified. It was established that the obtained proanthocyanidins mainly consist of procyanidin and prodelphinidin. It was shown that proanthocyanidins obtained from abies bark, in contrast to the proanthocyanidins isolated from pine bark described in the literature, contain gallic acid residues, which is typical for proanthocyanidins isolated from various types of tea

scholarly journals Numerical Optimization of the Abies Ethanol Lignin Sulfation Process with Sulfamic Acid in 1,4-Dioxane Medium in the Presence of Urea

2020 ◽  
pp. 232-246 ◽  
Author(s):  
Aleksandr S. Kazachenko ◽  
Natalya Yu. Vasilyeva ◽  
Irina G. Sudakova ◽  
Vladimir A. Levdansky ◽  
Maxim A. Lutoshkin ◽  
...  
Keyword(s):  
Mathematical Models ◽  
Sulfur Content ◽  
Numerical Optimization ◽  
Sulfamic Acid ◽  
Water Soluble ◽  
Variance Analysis ◽  
High Yield ◽  
Optimal Conditions ◽  
Calculation Methods

The process of abies ethanol lignin sulfation with sulfamic acid in 1,4-dioxane medium in the presence of urea was optimized by calculation methods. The influence of such factors, as the ratio of lignin/sulfating complex (L/SC), temperature and time of the sulfation process on the sulfur content in the resulting sulfated ethanol lignin and its yield, has been established. The variance analysis of the obtained mathematical models testifies their good predictive properties. The optimal conditions of abies ethanol lignin sulfation process, which provide the formation of water-soluble sulfated lignin with a high yield (to 100 % wt.) and sulfur content (up to 7.9 % wt.), have been established. They are: temperature of 95-100 °C, the ratio L/SC 1:2,3-1:2:9 and the time of the process 119-137 minutes

Enzymatic and Chemical Synthesis and Characterization of Poly-6-O-(10-undecylenoyl) D-Glucose

2012 ◽  
Vol 550-553 ◽  
pp. 787-791
Author(s):  
Chao Wei ◽  
Yin Zhen Wang ◽  
Wei Yan ◽  
Ping Jia Yao ◽  
Yuan An Wei
Keyword(s):  
Nmr Spectroscopy ◽  
Molecular Sieves ◽  
Immobilized Lipase ◽  
13C Nmr Spectroscopy ◽  
Synthesis And Characterization ◽  
Undecylenic Acid ◽  
Optimal Conditions ◽  
Release Agent ◽  
O 10

Immobilized lipase Novozym-435 catalyzed regioselective synthesis of glucose and undecylenic acid(UA) to produce glucose mono-ester in Organic solvents was investigated. Reactionconditions were tested in order to produce the mono-ester more rapidly and in higher yield, the optimal conditions were obtained as: temperature at 50°C,mole ratio of glucose toUA of 1:2,concentration of molecular sieves and enzyme used as 0.56mg/mL and 10mg/mL respectively . After the reaction, product was purified, and characterized by MS and 13C NMR spectroscopy, and determined as 6-O-(10-undercylenoyl)-D-glucose, The product was used as the starting material, K2S2O8 as a chemical initiator, to polymerize and form the sugar-containing polymer, which could be used for medicine release agent and other application of biological materials.

Ten-Vertex Polyhedral Monocarbaborane Chemistry. The Novel High-Yield Formation of the Ten-Vertex closo Compound [6-(PMe2Ph)-closo-1-CB9H9] from the Thermolysis of [8,8-(PMe2Ph)2-nido-8,7-PtCB9H11]

1993 ◽  
Vol 58 (12) ◽  
pp. 2924-2935 ◽  
Author(s):  
Jane H. Jones ◽  
Bohumil Štíbr ◽  
John D. Kennedy ◽  
Mark Thornton-Pett
Keyword(s):  
Nmr Spectroscopy ◽  
Diffraction Analysis ◽  
High Yield ◽  
Monoclinic Space Group ◽  
The Novel ◽  
X Ray Diffraction ◽  
Metal Centre ◽  
X Ray ◽  
Yield Formation ◽  
Boiling Toluene

Thermolysis of [8,8-(PMe2Ph)2-nido-8,7-PtCB9H11] in boiling toluene solution results in an elimination of the platinum centre and cluster closure to give the ten-vertex closo species [6-(PMe2Ph)-closo-1-CB9H9] in 85% yield as a colourles air stable solid. The product is characterized by NMR spectroscopy and single-crystal X-ray diffraction analysis. Crystals (from hexane-dichloromethane) are monoclinic, space group P21/c, with a = 903.20(9), b = 1 481.86(11), c = 2 320.0(2) pm, β = 97.860(7)° and Z = 8, and the structure has been refined to R(Rw) = 0.045(0.051) for 3 281 observed reflections with Fo > 2.0σ(Fo). The clean high-yield elimination of a metal centre from a polyhedral metallaborane or metallaheteroborane species is very rare.

scholarly journals (2S,3R,6R)-2-[(R)-1-Hydroxyallyl]-4,4-dimethoxy-6-methyltetrahydro-2H-pyran-3-ol

Molbank ◽  
10.3390/m1140 ◽  
2020 ◽  
Vol 2020 (2) ◽  
pp. M1140
Author(s):  
Jack Bennett ◽  
Paul Murphy
Keyword(s):  
Mass Spectrometry ◽  
Nmr Spectroscopy ◽  
Ir Spectroscopy ◽  
13C Nmr ◽  
Conjugate Addition ◽  
13C Nmr Spectroscopy ◽  
One Pot ◽  
1H And 13C Nmr ◽  
Esi Mass Spectrometry ◽  
The One

(2S,3R,6R)-2-[(R)-1-Hydroxyallyl]-4,4-dimethoxy-6-methyltetrahydro-2H-pyran-3-ol was isolated in 18% after treating the glucose derived (5R,6S,7R)-5,6,7-tris[(triethylsilyl)oxy]nona-1,8-dien-4-one with (1S)-(+)-10-camphorsulfonic acid (CSA). The one-pot formation of the title compound involved triethylsilyl (TES) removal, alkene isomerization, intramolecular conjugate addition and ketal formation. The compound was characterized by 1H and 13C NMR spectroscopy, ESI mass spectrometry and IR spectroscopy. NMR spectroscopy was used to establish the product structure, including the conformation of its tetrahydropyran ring.

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