scholarly journals Mild and controlled lignin methylation with trimethyl phosphate: towards a precise control of lignin functionality

2020 ◽  
Vol 22 (5) ◽  
pp. 1671-1680 ◽  
Author(s):  
Antoine Duval ◽  
Luc Avérous
Keyword(s):  
Trimethyl Phosphate ◽  
Oh Groups ◽  
Precise Control ◽  
Phenolic Oh Groups

A novel protocol for a mild, controlled and selective methylation of lignin phenolic OH groups with trimethylphosphate has been developed.

Statistical Analysis of the Relationship Between Antioxidant Activity and the Structure of Flavonoid Compounds

2019 ◽  
Vol 70 (9) ◽  
pp. 3103-3107 ◽  
Author(s):  
Ioana Glevitzky ◽  
Gabriela Alina Dumitrel ◽  
Mirel Glevitzky ◽  
Bianca Pasca ◽  
Pavel Otrisal ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Antioxidant Activities ◽  
Basic Structure ◽  
Oh Groups ◽  
Flavonoid Compounds ◽  
Chi Squared ◽  
Potential Link ◽  
Van Der Waals Surface ◽  
The Relationship ◽  
Phenolic Oh Groups

Using different methods of statistics, this paper aims to highlight the potential link between the antioxidant activity of flavonoids and the corresponding molecular descriptors. By calculating the descriptors (van der Waals surface (A), molar volume (V), partition coefficient (LogP), refractivity (R), polarizability (a), forming heat (Hformation), hydration energy (Ehidr), the dipole moment (mt)), together with antioxidant activities (RSA) calculated or taken from the literature, number of phenolic -OH groups and the presence (2) or absence (1) of C2=C3 double bond) for 29 flavonoid compounds and by intercorrelation between the studied parameters, the link between the number of phenolic groups grafted to the basic structure of flavonoids and their antioxidant activity was confirmed. Simultaneously, by using the chi-squared test and the intercorrelations matrix, a satisfactorily correlation coefficient (r2=0.5678; r=0.7536) between the structure of the flavonoids and their activity was obtained, fact that confirms the correlation of the antioxidant activity with the number of -OH phenolic groups.

Properties of humic and fulvic acids under the long-term use of fertilizers in a rice-wheat-cowpea system on a mollisol

2007 ◽  
Vol 55 (3) ◽  
pp. 293-298
Author(s):  
D. Das ◽  
Nand Ram
Keyword(s):  
Nutrient Management ◽  
Fulvic Acids ◽  
Oh Groups ◽  
Molecular Weights ◽  
Northern India ◽  
Carboxylic Groups ◽  
Long Term Experiment ◽  
C And N ◽  
Phenolic Oh Groups

The properties of humic (HA) and fulvic acids (FA) isolated from a 27-year-old long-term experiment with rice-wheat-cowpea on a Mollisol in northern India were evaluated for elemental composition and functional groups. As compared to fallow, C, H and N decreased, while O increased in the control, but the use of NPK+FYM over the years enhanced the C and N of humic substances. The carboxylic (-COOH) and phenolic-OH groups declined in the control, but improved with NPK+FYM in comparison to fallow. Carboxylic groups (-COOH) contributed about 2–3 times more in HA and 4–5 times more in FA than the respective phenolic-OH groups to the molecular weights of these fractions of soil organic matter. The results suggested the role of integrated nutrient management in maintaining active soil humus over the years.

scholarly journals Synthesis and Characterization of New Palladium(II) Schiff Base Complexes Derived from β-Diketones and Diamines

2020 ◽  
Vol 32 (5) ◽  
pp. 1039-1042
Author(s):  
Mridula Gupta ◽  
Sheela M. Valecha
Keyword(s):  
Schiff Base ◽  
Schiff Base Complexes ◽  
Schiff Base Ligands ◽  
Visible Absorption ◽  
Oh Groups ◽  
Uv Visible ◽  
Coordinated Water ◽  
Heterocyclic Schiff Bases ◽  
Phenolic Oh Groups

A new series of heterocyclic Schiff bases were prepared from condensation of 1-phenyl-3-methyl-4-acetyl/benzoyl-pyrazolone with 4,4′-diaminodiphenylmethane and 4,4′-diaminodiphenyl ether, resulting in the formation of four novel Schiff base ligands. These ligands were then treated with ethanolic solution of PdCl2, to form corresponding palladium(II) complexes. These complexes were characterized by elemental analysis, IR, 1H NMR, TGA, magnetic susceptibility measurements and UV-visible absorption spectroscopy. All the Pd(II) complexes were found to have one coordinated water molecule. Schiff base ligands chelated with the metal atom through two donor sites N and O of azomethine (-C=N-) and phenolic (-OH) groups, respectively.

BINDING OF RUTHENIUM(II)POLYPYRIDYL COMPLEXES WITH POLYPHENOLS IN AQUEOUS MEDIUM

2016 ◽  
Vol 1 (01) ◽  
pp. 77-81
Author(s):  
G.Allen Gnana Raj
Keyword(s):  
Aqueous Medium ◽  
Gallic Acid ◽  
Binding Constant ◽  
Structural Effect ◽  
Vital Role ◽  
Polypyridyl Complexes ◽  
Oh Groups ◽  
Absorption Intensity ◽  
Spectral Technique ◽  
Phenolic Oh Groups

The binding of three Ru(II)-polypyridyl complexes with polyphenols (gallic acid and quercetin) have been studied in aqueous medium at pH 11 by means of absorption spectral technique. The absorption and emission maximum of this complexes are in the range of 451-457 nm and 612-626 nm respectively. The binding constant (Kb) for these reactions are determined from the Benesi-Hildebrand equation using absorption intensity data.The observed binding constant values are sensitive to the nature of the ligand and the structure of the gallic acid and quercetin. Quercetin binds strongly with Ru(II) complexes than gallic acid owing to the presence of more phenolic –OH groups. Structural effect seems to play a vital role on the binding of the antioxidants with these complexes.

OXYGEN-CONTAINING FUNCTIONAL GROUPS IN ORGANIC SOILS AND THEIR RELATION TO THE DEGREE OF HUMIFICATION AS DETERMINED BY SOLUBILITY IN SODIUM PYROPHOSPHATE SOLUTION

1966 ◽  
Vol 46 (3) ◽  
pp. 237-243 ◽  
Author(s):  
M. Schnitzer ◽  
J. G. Desjardins
Keyword(s):  
Analytical Data ◽  
Group Analysis ◽  
Organic Soil ◽  
Sodium Pyrophosphate ◽  
Organic Soils ◽  
Oh Groups ◽  
Functional Group Analysis ◽  
Phenolic Oh Groups

Carboxyls, phenolic and alcoholic hydroxyls, carbonyls, and methoxyls were determined in 20 organic soil samples that ranged from peats, mucky peats, peaty mucks to mucks. The absorbance of a sodium pyrophosphate extract of each sample served as basis for grouping the samples into three broad classes: (i) peat, (ii) mucky peat – peaty muck, and (iii) muck.A statistical analysis of the analytical data showed that (a) the determination of COOH and of OCH3 groups distinguished between the peat and muck classes, and (b) measurement of alcoholic OH groups differentiated between the peat class and the intermediate class and between the peat and muck classes. The experimental data indicated that increased humification was associated with increases in COOH, OCH3, and to a lesser extent of C==O groups, increased solubility in dilute sodium pyrophosphate solution, decreases in alcoholic OH groups but practically no changes in phenolic OH groups. It is suggested that functional group analysis could be used as a supplementary diagnostic tool for assessing the degree of humification of organic matter in organic soils and could thus serve as an aid in the classification of organic soils.

Synthesis of Monofunctionalized Calix[5]arenes

Synthesis ◽  
2017 ◽  
Vol 50 (03) ◽  
pp. 676-684 ◽  
Author(s):  
Arne Lützen ◽  
Björn Ingenfeld ◽  
Steffen Straub ◽  
Christopher Frömbgen
Keyword(s):  
Hydrogen Bonds ◽  
Functional Groups ◽  
Functional Group ◽  
Building Blocks ◽  
Cone Conformation ◽  
Oh Groups ◽  
Tert Butyl ◽  
Fragment Condensation ◽  
Molecular Architectures ◽  
Phenolic Oh Groups

Seven OH-free and O-permethylated monofunctionalized calix[5]arenes carrying either additional methyl or tert-butyl groups are prepared following fragment condensation protocols. This strategy proves to be superior to previous approaches. Calix[5]arenes with free OH groups all adopt a cone conformation stabilized by a seam of hydrogen bonds at the lower rim. Post-condensation modifications, i.e., methylation of phenolic OH groups or functional group interconversions can also be achieved. Bulky tert-butyl groups are also found to stabilize the cone conformations of O-methylated compounds. These compounds offer versatile functional groups that make these concave molecules interesting building blocks for the synthesis of more sophisticated molecular architectures.

Ion-exchange properties and swelling capacity of leaf cell wall of Arctic plants

2018 ◽  
Vol 8 (1) ◽  
pp. 132-142
Author(s):  
Elena N. Terebova ◽  
Evgenya F. Markovskaya ◽  
Natalya Yu. Shmakova
Keyword(s):  
Cell Wall ◽  
Ion Exchange ◽  
Exchange Capacity ◽  
Carboxyl Groups ◽  
Leaf Cell ◽  
Oh Groups ◽  
Arctic Plants ◽  
Cassiope Tetragona ◽  
Swelling Capacity ◽  
Phenolic Oh Groups

Ion-exchange (number of functional group) properties and swelling capacity of leaf cell walls of plant species Betula nana, Salix polaris, Dryas octopetala and Cassiope tetragona from Western Spitsbergen Island were investigated. It was found out that cell wall of Arctic plants is cation exchanger which has similar functional groups (amine groups, carboxyl groups and phenolic OH-groups) with cell wall of boreal plants. In all investigated species, the highest percentage in the structure of the cell wall was recorded for the carboxyl groups of hydroxycinnamic acids and phenolic OH-groups, which are part of phenolic compounds. In comparison with species from other climatic zones leaf cell wall of arctic plants has in 2–3 times higher amount of ion exchange groups of all types as well as the higher values of swelling coefficients. It was proposed that the high values of the ion-exchange capacity and swelling coefficient of the cell wall of all studied species contribute to greater water flow system by the apoplast and enhance the metabolic processes in the cell wall of plants at high latitudes.

scholarly journals Indonesian plants with potential as an anti-diabetes mellitus agent

2020 ◽  
Vol 1 (2) ◽  
pp. 28-31
Author(s):  
Rachmat Hidayat ◽  
Lusia Hayati ◽  
Nita Parisa
Keyword(s):  
Diabetes Mellitus ◽  
Antioxidant Activity ◽  
Natural Antioxidants ◽  
Pancreatic Tissue ◽  
Oh Groups ◽  
Rat Pancreas ◽  
The World ◽  
Long Time ◽  
Treatment Of Diabetes ◽  
Phenolic Oh Groups

Diabetes Mellitus (DM) is a degenerative disease that continues to increase in numberin Indonesia and is a disease that is spread throughout the world due to unbalancednutritional conditions. Treatment of diabetes mellitus is a chronic and lifelongtreatment. Treatment of diabetes mellitus, such as the use of insulin and oralantihyperglycemia drugs, is relatively expensive, is used for a long time and can causeunwanted side effects. There are many plants that have potential as antihyperglycemiadrugs. One of the active compounds that act as antihyperglycemia isflavonoids.Flavonoids derived from various types of plants studied are thought to actas antihyperglycemic agents. Flavonoids are known to have the ability to scavenge freeradicals or act as natural antioxidants. The antioxidant activity of flavonoids is relatedto phenolic –OH groups which can capture or neutralize free radicals (such as ROS orRNS). Flavonoids can play a role in pancreatic tissue damage caused by DNA alkylationdue to alloxan induction as a result of improving the morphology of the rat pancreas(Prameswari and Widjanarko, 2014).

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