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

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 Radical Dehalogenation and Purine Nucleoside Phosphorylase E. coli: How Does an Admixture of 2′,3′-Anhydroinosine Hinder 2-fluoro-cordycepin Synthesis

Biomolecules ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 539
Author(s):  
Alexey L. Kayushin ◽  
Julia A. Tokunova ◽  
Ilja V. Fateev ◽  
Alexandra O. Arnautova ◽  
Maria Ya. Berzina ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Chemical Synthesis ◽  
Purine Nucleoside Phosphorylase ◽  
Purine Nucleoside ◽  
Preparative Synthesis ◽  
Nucleoside Phosphorylase ◽  
E Coli ◽  
First Time

During the preparative synthesis of 2-fluorocordycepin from 2-fluoroadenosine and 3′-deoxyinosine catalyzed by E. coli purine nucleoside phosphorylase, a slowdown of the reaction and decrease of yield down to 5% were encountered. An unknown nucleoside was found in the reaction mixture and its structure was established. This nucleoside is formed from the admixture of 2′,3′-anhydroinosine, a byproduct in the preparation of 3-′deoxyinosine. Moreover, 2′,3′-anhydroinosine forms during radical dehalogenation of 9-(2′,5′-di-O-acetyl-3′-bromo- -3′-deoxyxylofuranosyl)hypoxanthine, a precursor of 3′-deoxyinosine in chemical synthesis. The products of 2′,3′-anhydroinosine hydrolysis inhibit the formation of 1-phospho-3-deoxyribose during the synthesis of 2-fluorocordycepin. The progress of 2′,3′-anhydroinosine hydrolysis was investigated. The reactions were performed in D2O instead of H2O; this allowed accumulating intermediate substances in sufficient quantities. Two intermediates were isolated and their structures were confirmed by mass and NMR spectroscopy. A mechanism of 2′,3′-anhydroinosine hydrolysis in D2O is fully determined for the first time.

scholarly journals Fractionation of Birch Wood by Integrating Alkaline-Acid Treatments and Hydrogenation in Ethanol over a Bifunctional Ruthenium Catalyst

Catalysts ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1362
Author(s):  
Boris N. Kuznetsov ◽  
Sergey V. Baryshnikov ◽  
Angelina V. Miroshnikova ◽  
Aleksandr S. Kazachenko ◽  
Yuriy N. Malyar ◽  
...  
Keyword(s):  
Microcrystalline Cellulose ◽  
Catalytic Hydrogenation ◽  
Liquid Product ◽  
Gel Permeation Chromatography ◽  
Ruthenium Catalyst ◽  
Birch Wood ◽  
Gaseous Products ◽  
Liquid Products ◽  
First Time

For the first time, the fractionation of birch wood into microcrystalline cellulose, xylose and methoxyphenols is suggested based on the integration of alkali-acid pretreatments and hydrogenation in ethanol over a bifunctional Ru/C catalyst. It is established that removal of hemicelluloses during pretreatments of birch wood influences the yields of the liquid, gaseous and solid products of the non-catalytic and catalytic hydrogenation of pretreated samples in ethanol at 225 °C. The bifunctional Ru/carbon catalyst affects in different ways the conversion and yields of products of hydrogenation of the initial and acid- and alkali-pretreated birch wood. The most noticeable influence is characteristic of the hydrogenation of the acid-pretreated wood, where in contrast to the non-catalytic hydrogenation, the wood conversion and the yields of liquid products increase but the yields of the solid and gaseous products decrease. GC-MS, gel permeation chromatography and elemental analysis were used for characterization of the liquid product composition. The molecular mass distribution of the liquid products of hydrogenation of the initial and pretreated wood shifts towards the low-molecular range in the presence of the catalyst. From the GC-MS data, the contents of monomer compounds, predominantly 4-propylsyringol and 4-propanolsyringol, increase in the presence of the ruthenium catalyst. The solid products of catalytic hydrogenation of the pretreated wood contain up to 95 wt% of cellulose with the structure, similar to that of microcrystalline cellulose.

scholarly journals NEW PHARMACOLOGICALLY ACTIVE COMPOUNDS BASED ON 5-HYDROXY-7-METHOXY-2-PHENYLCHROMAN-4-ONE

2021 ◽  
Vol 3 ◽  
pp. 119-127
Author(s):  
G.M. Baisarov ◽  
◽  
S.M. Adekenov ◽  
Keyword(s):  
Nmr Spectroscopy ◽  
13C Nmr ◽  
Potassium Carbonate ◽  
13C Nmr Spectroscopy ◽  
1H And 13C Nmr ◽  
Pharmacologically Active ◽  
Pharmacologically Active Compounds ◽  
First Time

The reaction of 5-hydroxy-7-methoxy-2-phenylchroman-4-one with dibromoalkanes in acetone in the presence of potassium carbonate proceeds according to the Michael’s retro-reaction O-alkylation and leads to the formation of the corresponding 2-(bromo-alkoxy) chalcones. The structure of the synthesized compounds was confirmed by IR-, 1H- and 13C-NMR spectroscopy. The cytotoxic, hepatoprotective and anti-inflammatory effects of chalcone derivatives (2-3) were studied for the first time in vitro and in vivo.

27Al-MAS-NMR-Untersuchungen des thermischen Abbaus von NH4Al(SO4)2·12H2O / 27Al-MAS-NMR Studies on the Thermolysis of NH4Al(SO4)2· 12H2O

1991 ◽  
Vol 46 (11) ◽  
pp. 1515-1518 ◽  
Author(s):  
Gerhard Wegner ◽  
Gert Blumenthal ◽  
Dirk Müller ◽  
Dirk-Henning Menz ◽  
Antje Schmalstieg
Keyword(s):  
Nmr Spectroscopy ◽  
Structural Changes ◽  
Chemical Shifts ◽  
Mas Nmr ◽  
Nmr Studies ◽  
High Stage ◽  
27Al Mas Nmr ◽  
High Resolution Nmr ◽  
First Time

Products of the thermolysis of NH4Al-alum were prepared under dried air and characterized by X-ray powder diffraction, thermogravimetry, and for the first time by solid-state 27Al-MAS-NMR spectroscopy. It was found, that high resolution NMR spectroscopy is applicable to follow up the thermal decomposition and to indicate even minor structural changes. 27Al-MAS-NMR spectra show peaks with characteristic chemical shifts for octahedral Al-units up to a high stage of thermolysis. During the decomposition of Al2(SO4)3 to γ-Al2O3 we again observed three-peak spectra with the specific signal at ≈ 35 ppm for penta-coordinated Al ions as recently proved for the thermolysis of AlCl3 · 6 H2O.

One-pot synthesis of the new Hydroxamic acid and its complexes with metals

2022 ◽  
Vol 19 ◽  
Author(s):  
Gulu Abbasova ◽  
Ajdar Medjidov
Keyword(s):  
Nmr Spectroscopy ◽  
Thermogravimetric Analysis ◽  
Hydroxamic Acid ◽  
Uv Spectroscopy ◽  
Molar Ratio ◽  
One Pot ◽  
Ethanol Medium ◽  
Physicochemical Methods ◽  
Colored Complexes ◽  
First Time

Abstract: A one-pot conversion of 2-hydroxy-1-naphthoic aldehyde to hydroxamic acid was described. An efficient photoorganocatalytic method of synthesis was developed. The obtained hydroxamic acid was identified by various physicochemical methods such as IR, UV- and NMR-spectroscopy. Solid colored complexes of copper (II) and iron (II), respectively, green and brown colours with the obtained hydroxamic acid were synthesized in ethanol medium for the first time. The molar ratio of ligand and metal in the complex was 2:1. Their structures were established using IR, UV- spectroscopy and thermogravimetric analysis.

scholarly journals New Kaempferol 3,7-Diglycosides from Asplenium ruta-muraria and Asplenium altajense

2015 ◽  
Vol 10 (3) ◽  
pp. 1934578X1501000 ◽  
Author(s):  
Tsukasa Iwashina ◽  
Junichi Kitajima ◽  
Takayuki Mizuno ◽  
Sergey V. Smirnov ◽  
Oyunchimeg Damdinsuren ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Adjacent Area ◽  
Altai Mountains ◽  
A Minor ◽  
First Time ◽  
Minor Compound ◽  
C Nmr

A flavonoid was isolated from the fronds of Asplenium ruta-muraria and A. altajense (Aspleniaceae) collected in the Altai Mountains and adjacent area. The compound was identified as kaempferol 3- O- β-[(6″′- E-caffeoylglucopyranosyl)-(1→3)-glucopyranoside]-7- O- β-glucopyranoside (1) by UV, 1H and 13C NMR spectroscopy, LC-MS, and acid and alkaline hydrolyses. Another flavonoid (2) was isolated from A. altajense, as a minor compound, together with 1 and identified as deacylated compound 1, i.e. kaempferol 3- O-laminaribioside-7- O-glucoside. They were found in nature for the first time.

scholarly journals Development of an Efficient Protocol for Cimifugin Isolation from Peucedanum schottii and Evaluation of Enzyme Inhibitory Activity

2016 ◽  
Vol 11 (8) ◽  
pp. 1934578X1601100
Author(s):  
Ewelina Kozioł ◽  
Ilkay Erdogan Orhan ◽  
F. Sezer Senol ◽  
Kalina Alipieva ◽  
Milen Georgiev ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Ethyl Acetate ◽  
Crude Extract ◽  
Inhibitory Activity ◽  
High Performance ◽  
Performance Counter ◽  
Inhibitory Potential ◽  
Counter Current ◽  
First Time ◽  
Analytical Scale

The dichloromethane (DCM) extract of the fruits of Peucedanum schottii Besser ex DC. (Apiaceae) was subjected to high-performance counter-current chromatography (HPCCC) for the efficient and fast separation (30 min) and isolation of cimifugin using an ethyl acetate: water (1:1 v/v, K = 1.01) system. The analytical scale-optimized separation was easily scaled to semi-preparative conditions. Cimifugin (11.25% yield, 96.5% purity) was isolated for the first time from P. schottii and characterized by NMR spectroscopy. Cimifugin and the crude DCM extract were evaluated using ELISA microtiter assays for their inhibitory potential against the cholinesterases (acetylcholinesterase - AChE and butyrylcholinesterase - BChE), and tyrosinase (TYR), which are key enzymes for the treatment of some neurodegenerative diseases, i.e. Alzheimer's and Parkinson's. The crude extract exhibited a weak inhibitory activity against AChE, BChE, and TYR (4.2, 35.5, and 0% at 100 μg mL−1 and 10.3, 40.0, and 12.2% at 200 μg mL−1, respectively), while cimifugin displayed low to moderate inhibition towards AChE and BChE (3.1 and 21.6%, respectively) at 200 μg mL−1.

scholarly journals Two New Isomers of Palmityl-4-hydroxycinnamate from Flowers of Taraxacum Species

2016 ◽  
Vol 11 (6) ◽  
pp. 1934578X1601100
Author(s):  
Matej Dudáš ◽  
Mária Vilková ◽  
Tibor Béres ◽  
Miroslav Repčák ◽  
Pavol Mártonfi
Keyword(s):  
Nmr Spectroscopy ◽  
Pollen Grains ◽  
2D Nmr ◽  
Male Sterile ◽  
2D Nmr Spectroscopy ◽  
First Time

Two isomers, (Z)- and (E)-palmityl 4-hydroxycinnamate [hexadecyl(2Z)-3-(4-hydroxyphenyl)prop-2-enoate and hexadecyl(2E)-3-(4-hydroxyphenyl)prop-2-enoate] were isolated for the first time from ligulate flowers of Taraxacum linearisquameum Soest (sect. Taraxacum). The highest amount of these compounds was detected in pollen grains; 0.26 mg/100 mg DW of the (E)-isomer and 0.096 mg/100 mg DW of the (Z)-isomer. The structures of these compounds were elucidated by a combination of HPLC-ESI-Qtof-MS and ID and 2D NMR spectroscopy. Their presence was confirmed in other species of Taraxacum, but they were not found in the male-sterile triploid agamospermous taxon T. parnassicum.

scholarly journals A Phenylpropanoid and Biflavonoids from the Needles of Cephalotaxus harringtonia var. harringtonia

2017 ◽  
Vol 12 (11) ◽  
pp. 1934578X1701201 ◽  
Author(s):  
Anju Mendiratta (Nee Chugh) ◽  
Rameshwar Dayal ◽  
John P. Bartley ◽  
Graham Smith
Keyword(s):  
Nmr Spectroscopy ◽  
Oral Dose ◽  
Spectral Data ◽  
2D Nmr ◽  
Hepatoprotective Activity ◽  
X Ray Diffraction ◽  
Soluble Extract ◽  
2D Nmr Spectroscopy ◽  
X Ray ◽  
First Time

A phenylpropanoid [2-(3-methoxy-4-hydroxyphenyl)-propane-1,3-diol] (1) together with four known biflavonoids namely 7, 4′, 7′″, 4′″-tetra- O-methyl amentoflavone (2); 7, 4′, 7″-tri- O-methyl amentoflavone (3); ginkgetin (4); sequoiaflavone (5) were isolated from the acetone soluble extract of needles of Cephalotaxus harringtonia var. harringtonia. Their structures were elucidated mainly on the basis of interpretation of 1D and 2D NMR spectroscopy and X-ray diffraction studies. The detailed spectral data of phenylpropanoid have been described for the first time. Ginkgetin (4) exhibited significant hepatoprotective activity in rat at 6 mg/kg oral dose level.

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