scholarly journals The Study of the Reaction of Pectin-Ag(0) Nanocomposites Formation

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Nadezhda Viktorovna Ivanova ◽  
Natalya Nikolaevna Trofimova ◽  
Lydmila Alexandrovna Es'kova ◽  
Vasilyi Anatolievich Babkin
Keyword(s):  
Aqueous Solutions ◽  
Larix Sibirica ◽  
Side Chains ◽  
Chemical Transformations ◽  
Reaction Conditions ◽  
Rhamnogalacturonan I ◽  
Spectroscopic Analyses ◽  
Furanose Form ◽  
Branched Structure ◽  
C Nmr

Pectin polysaccharides (PSs) were isolated from a bark of Larix sibirica Ledeb. Structure of PS fragments determined by chemical transformations, chromatography, and spectroscopic analyses was found to be a linear galacturonane comprising 1,4-linked α-D-GalpA residues and a rhamnogalacturonan I (RG-I). The fifth part of galacturonane residues was methyl esterified at at C-2 and/or C-3 and C-6 atoms. Some of RG-I side chains were identified as arabinogalactan subunits with highly branched structure consisting of linear backbone with3,6)-β-D-Galp-(1residues, substituted at C-6 by neutral side chains. This side chains contained2,5)-α-L-Araf-(1and3,5)-α-L-Araf-(1residues and terminal arabinose in the pyranose and furanose form. It was found that “pectin-Ag(0)” nanobiocomposites were formed via the interaction between PS aqueous solutions and silver nitrate, with PS playing both reducing and stabilizing functions. It was shown that the content of Ag(0) particles in “pectin-Ag(0)” depended on the reaction conditions and can range from 0.1 to 72 %, the size of Ag(0) particles being 3–27 nm. Using 13C NMR technique, it was revealed that PS underwent destructive changes and they they were more considerable, more than the lot of Ag(I) that was inputed into the reactionary medium.

scholarly journals Syntheses and solution properties of water-soluble poly(p-phenylene)s bearing oligo(ethylene oxide) and trialkylamino side groups

e-Polymers ◽  
2002 ◽  
Vol 2 (1) ◽  
Author(s):  
Steffen Traser ◽  
Patrick Wittmeyer ◽  
Matthias Rehahn
Keyword(s):  
Ethylene Oxide ◽  
Aqueous Media ◽  
Amino Nitrogen ◽  
Water Soluble ◽  
Side Chains ◽  
Amino Groups ◽  
Reaction Conditions ◽  
Substitution Pattern ◽  
Polycondensation Process ◽  
C Nmr

AbstractPd-catalyzed Suzuki coupling is used to prepare poly(p-phenylene)s (PPPs) bearing oligo(ethylene oxide)s (OEOs) and trialkylamino groups as lateral substituents. The OEO substituents require very specific reaction conditions during monomer synthesis - presumably due to their coordinating oxygen atoms - but do not affect the subsequent Pd-catalyzed polycondensation process. In contrast to this, the lateral amino groups lower the degree of polycondensation of the PPPs considerably when their nitrogen atom is placed in the β-position of the side chains. When there is a longer spacer group between the amino nitrogen and the aromatic ring to be coupled, however, high-molecular-weight PPPs can be obtained. Provided an appropriate substitution pattern and long OEO side chains are used, the resulting PPPs are readily soluble not only in organic solvents but even in aqueous media. For one of these PPPs, the degree of protonation has been determined as a function of pH, using 1H and 13C NMR spectroscopy as well as potentiometry. It is shown that the polymer is completely deprotonated at pH > 10.5 and quantitatively protonated at pH < 4.0.

Polysaccharide Structures in the Outer Mucilage of Arabidopsis Seeds Visualized by AFM

2020 ◽  
Author(s):  
MAK Williams ◽  
V Cornuault ◽  
AH Irani ◽  
VV Symonds ◽  
J Malmström ◽  
...  
Keyword(s):  
Average Length ◽  
American Chemical Society ◽  
Md Simulations ◽  
Chemical Society ◽  
Side Chains ◽  
Rhamnogalacturonan I ◽  
Afm Imaging ◽  
Minor Population ◽  
The Stability ◽  
A Minor

© 2020 American Chemical Society. Evidence is presented that the polysaccharide rhamnogalacturonan I (RGI) can be biosynthesized in remarkably organized branched configurations and surprisingly long versions and can self-assemble into a plethora of structures. AFM imaging has been applied to study the outer mucilage obtained from wild-type (WT) and mutant (bxl1-3 and cesa5-1) Arabidopsis thaliana seeds. For WT mucilage, ordered, multichain structures of the polysaccharide RGI were observed, with a helical twist visible in favorable circumstances. Molecular dynamics (MD) simulations demonstrated the stability of several possible multichain complexes and the possibility of twisted fibril formation. For bxl1-3 seeds, the imaged polymers clearly showed the presence of side chains. These were surprisingly regular and well organized with an average length of ∼100 nm and a spacing of ∼50 nm. The heights of the side chains imaged were suggestive of single polysaccharide chains, while the backbone was on average 4 times this height and showed regular height variations along its length consistent with models of multichain fibrils examined in MD. Finally, in mucilage extracts from cesa5-1 seeds, a minor population of chains in excess of 30 μm long was observed.

Effects of salts on the kinetics of oxidation of alkenes by thallic salts in aqueous solutions

1981 ◽  
Vol 46 (3) ◽  
pp. 693-700 ◽  
Author(s):  
Milan Strašák ◽  
Jaroslav Majer
Keyword(s):  
Aqueous Solutions ◽  
Phase Transfer ◽  
Heterogeneous Reaction ◽  
Qualitative Model ◽  
Kinetic Effect ◽  
Tetraalkylammonium Salts ◽  
Reaction Conditions ◽  
Kinetics Of Oxidation ◽  
Kinetics Of ◽  
Heterogeneous Reaction Conditions

The kinetics of oxidation of alkenes by thallic sulphate in aqueous solutions, involving the two reaction steps-the hydroxythallation and the dethallation - was studied, and the effect of salts on the kinetics was examined; this made it possible to specify more precisely the reaction mechanism and to suggest a qualitative model of the reaction coordinate. It was found that in homogeneous as well as in heterogeneous reaction conditions, the reaction can be accelerated appreciably by adding tetraalkylammonium salts. These salts not only operate as catalysts of the phase transfer, but also exert a significant kinetic effect, which can be explained with a simplification in terms of a stabilization of the transition state of the reaction.

scholarly journals Meta-studtite stability in aqueous solutions. Impact of HCO3−, H2O2 and ionizing radiation on dissolution and speciation

2021 ◽  
Author(s):  
Junyi Li ◽  
Zoltán Szabó ◽  
Mats Jonsson
Keyword(s):  
Aqueous Solution ◽  
Ionizing Radiation ◽  
Aqueous Solutions ◽  
Carbonate Complexes ◽  
C Nmr

Four different uranyl-(peroxide)-carbonate complexes were identified during studtite and meta-studtite dissolution in aqueous solution containing 10 mM HCO3− by 13C NMR.

NMR-Structural Investigations of a β3-Dodecapeptide with Proteinogenic Side Chains in Methanol and in Aqueous Solutions

2002 ◽  
Vol 85 (5) ◽  
pp. 1197 ◽  
Author(s):  
Touraj Etezady-Esfarjani ◽  
Christian Hilty ◽  
Kurt Wüthrich ◽  
Magnus Rueping ◽  
Jürg Schreiber ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Side Chains ◽  
Structural Investigations

scholarly journals XVII.—Electrolytic Synthesis of Dibasic Acids

1895 ◽  
Vol 37 (2) ◽  
pp. 361-379
Author(s):  
A. Crum Brown ◽  
James Walker
Keyword(s):  
Aqueous Solutions ◽  
Succinic Acid ◽  
Homologous Series ◽  
Side Chains ◽  
Potassium Salts ◽  
Concentrated Aqueous Solutions

In our former paper we described the results obtained by electrolysing concentrated aqueous solutions of the ethyl-potassium salts of normal saturated dibasic acids. The chief products were shown to be diethyl compound ethers of the same homologous series, and the formation of these compound ethers was shown to occur in accordance with the equation: 2C2H5·O·ĊO·R˝·CO·O- = C2H5·O·CO·R˝R˝CO·O·C2H5 + 2CO2. We now find that precisely similar results are obtained by electrolysing the corresponding compounds derived from saturated dibasic acids with side chains. We have thus been able to effect the synthesis of acids of the succinic acid series, in which hydrogen is symmetrically replaced by alcohol radicals of the form CnH2n+1.

scholarly journals Flavonoids from Curcuma longa Leaves and their NMR Assignments

2015 ◽  
Vol 10 (1) ◽  
pp. 1934578X1501000 ◽  
Author(s):  
Chia-Ling Jiang ◽  
Sheng-Fa Tsai ◽  
Shoei-Sheng Lee
Keyword(s):  
Nmr Assignments ◽  
Soluble Fraction ◽  
Curcuma Longa ◽  
2D Nmr ◽  
Etoh Extract ◽  
Spectroscopic Analyses ◽  
Nmr Data ◽  
The Common ◽  
Reported Data ◽  
C Nmr

Chemical investigation of the n-BuOH-soluble fraction of the EtOH extract of the aerial part of Curcuma longa led to the isolation of 11 flavonol glycosides and one dihydroflavonol glucoside (1) via chromatography over Sephadex LH-20 and Lobar RP-18 columns. Although they are known, the 1H and 13C NMR data recorded in CD3OD rather than the common DMSO- d6 are doubly checked via extensive 2D NMR spectroscopic analyses, leading to some revisions of the reported data, especially for the glycon part.

scholarly journals Synthesis and anti-acetylcholinesterase activities of novel glycosyl coumarylthiazole derivatives

2020 ◽  
pp. 174751982094835
Author(s):  
You-Xian Wang ◽  
Shu-Hao Liu ◽  
Zhong-Bai Shao ◽  
Lian-Gong Cao ◽  
Kai-Jun Jiang ◽  
...  
Keyword(s):  
Electrospray Ionization ◽  
New Products ◽  
Reaction Conditions ◽  
Inhibitory Rate ◽  
Inhibitory Activities ◽  
Ellman’S Method ◽  
New Compounds ◽  
C Nmr

Eleven glycosyl coumarylthiazole derivatives are synthesized by cyclization and condensation of glycosyl thiourea with 3-bromoacetyl coumarins in ethanol. The reaction conditions are optimized and good yields of products (80%–95%) are obtained. The structures of all new products were confirmed by IR, 1H and 13C NMR, and by HRMS (electrospray ionization). The in vitro acetylcholinesterase (AChE) inhibitory activities of these new compounds are tested by Ellman’s method. Among them, N-(2-acetamido-3,4,6-tri- O-acetyl-2-deoxy-β-D-glucopyranosyl)-4-(6-nitrocoumarinyl)-1,3-thiazole-2-amine showed the best activity with an in vitro AChE inhibitory rate of 58% and an IC50 value of 12 ± 0.38 μg/mL.

Sign in / Sign up

Export Citation Format

Share Document