Comparative Studies of Brown Coal and Lignin. II. The Action of Concentrated Alkali at Elevated Temperatures

A study was made of the products formed by treating brown coal or lignin with concentrated aqueous or ethanolic alkali at 200 �C. With brown coals a major redistribution of the oxygen-containing functional groups appeared to occur, because the products contained aliphatically linked carboxyl groups and aliphatic hydroxyl, as well as phenolic hydroxyl groups. The behaviour of lignin under the same conditions was less clear but sufficiently similar to that of brown coal to suggest that reactions of the same type were occurring in both cases. Reactions involving decarboxylation, ring scission of dihydric phenol structures, and subsequent hydrogenation are suggested tentatively as the main steps in the formation of the products. The results provide some additional evidence for the view that there is a simple chemical relation between Victorian brown coal and lignin.

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THE PROBLEM OF PLASTEIN FORMATION: II. THE CHEMICAL CHANGES INVOLVED IN PLASTEIN FORMATION BY PAPAIN AND BY PEPSIN

Canadian Journal of Research ◽

10.1139/cjr40b-034 ◽

1940 ◽

Vol 18b (9) ◽

pp. 272-280 ◽

Cited By ~ 3

Author(s):

H. B. Collier

Keyword(s):

Enzymatic Hydrolysis ◽

Free Amino ◽

Essential Role ◽

Phenolic Hydroxyl ◽

Carboxyl Groups ◽

Hydroxyl Groups ◽

Chemical Changes ◽

Phenolic Hydroxyl Groups ◽

Hydrolysis Of

It has been confirmed that free amino and carboxyl groups disappear during plastein formation from concentrated proteose by crystalline pepsin. Using papain, the changes are obscured by simultaneous hydrolysis. Enzymatic hydrolysis of the plasteins results in the liberation of free amino and carboxyl groups.Reactive "tyrosine" decreases during plastein formation by either enzyme. The same groups are liberated on enzymatic hydrolysis of the plasteins, in a manner analogous to that which takes place in the hydrolysis of typical proteins.It is concluded that in so far as the changes in amino, carboxyl, and "tyrosine" groups are concerned, the plasteins are similar to typical proteins. It is further suggested that the phenolic hydroxyl groups of tyrosine play an essential role in the structure of the protein molecule.Benzaldehyde was found to have no effect on the formation of plastein from proteose by crystalline pepsin.

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A novel amino acid analysis method using derivatization of multiple functional groups followed by liquid chromatography/tandem mass spectrometry

The Analyst ◽

10.1039/c4an01672f ◽

2015 ◽

Vol 140 (6) ◽

pp. 1965-1973 ◽

Cited By ~ 24

Author(s):

Yohei Sakaguchi ◽

Tomoya Kinumi ◽

Taichi Yamazaki ◽

Akiko Takatsu

Keyword(s):

Mass Spectrometry ◽

Amino Acid ◽

Functional Groups ◽

Amino Acid Analysis ◽

Hydroxyl Groups ◽

Tandem Mass ◽

Analysis Method ◽

Chromatography Tandem Mass Spectrometry ◽

Liquid Chromatography Tandem Mass ◽

Phenolic Hydroxyl Groups

We have developed a novel amino acid analysis method using derivatization of multiple functional groups (amino, carboxyl, and phenolic hydroxyl groups).

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TERPENOIDS: V. SENEGENIN: FUNCTIONAL GROUPS AND PART STRUCTURE

Canadian Journal of Chemistry ◽

10.1139/v64-073 ◽

1964 ◽

Vol 42 (3) ◽

pp. 491-501 ◽

Cited By ~ 18

Author(s):

J. J. Dugan ◽

P. De Mayo ◽

A. N. Starratt

Keyword(s):

Functional Groups ◽

Empirical Formula ◽

Carboxyl Groups ◽

Hydroxyl Groups ◽

Carboxyl Group ◽

Secondary Hydroxyl ◽

Part Structure ◽

Oxygen Atoms

Senegenin, the sapogenin from Polygalasenega has been shown to contain chlorine; it has the empirical formula C30OH45O6Cl. The oxygen atoms, contrary to earlier work, are contained in two carboxyl groups and two secondary hydroxyl groups. There is one isolated ethylenic linkage. The environment of the hydroxylic functions and one carboxyl group has been shown to be as in (XI).

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Sorption of 137Cs and 90Sr on Organic Sorbents

Applied Sciences ◽

10.3390/app112311531 ◽

2021 ◽

Vol 11 (23) ◽

pp. 11531

Author(s):

Petr Belousov ◽

Anna Semenkova ◽

Yulia Izosimova ◽

Inna Tolpeshta ◽

Anna Romanchuk ◽

...

Keyword(s):

Functional Groups ◽

Brown Coal ◽

Exchange Capacity ◽

Buffering Capacity ◽

Hard Coal ◽

Ph Values ◽

High Moor ◽

Brown Coals ◽

Ph Range ◽

High Moor Peat

The present study examines the sorption of Cs (I) and Sr (II) on organic sorbents in the pH range from 2 to 10, as well as the mechanisms of their binding. In order to determine the influence of the physical properties and the quantity of functional groups of the organic sorbents on sorption, experiments were carried out on organic materials of varying degrees of metamorphism: high-moor peat, hard and brown coals and shungite. A detailed description of their mineral composition, cation exchange capacity, buffering capacity and elemental composition of sorbents is provided. XRD, XRF, SEM and BET adsorption methods were used for assaying. As a result of the conducted research, it can be concluded that Sr (II) showed a higher sorption per unit specific surface area than Cs (I) in the studied range of concentrations and pH values. Sr (II) sorption decreases in the following order: high-moor peat > brown coal > shungite > hard coal. The sorption of Cs (I) is highest on brown coal and lesser for high-moor peat, shungite and hard coal. It is suggested that Cs (I) and Sr (II) can be fixed on carboxyl functional groups and Cs (I), possibly, in insignificant amounts on phenolic hydroxyls of all four studied organic sorbents.

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Obtaining humic materials by mechanochemical reduction

MATEC Web of Conferences ◽

10.1051/matecconf/202134001001 ◽

2021 ◽

Vol 340 ◽

pp. 01001

Author(s):

Natalya Yudina ◽

Elizaveta Linkevich ◽

Anna Saveleva ◽

Oleg Lomovsky

Keyword(s):

Mechanical Activation ◽

Functional Groups ◽

Fulvic Acids ◽

Carboxyl Groups ◽

Hydroxyl Groups ◽

Humic And Fulvic Acids ◽

Humic Materials ◽

Spectral Coefficients ◽

Mechanochemical Modification

In the study, a mechanochemical modification of peat was carried out, leading to an increase in the number of functional groups and an increase in the solubility of humic complexes with metals. It was shown that the mechanical activation of peat in the presence of Zn significantly increased the yield of extractable fulvic acids. An analysis of the spectral coefficients showed that humic and fulvic acids extracted from peat were characterized by an increased content of alcohol hydroxyl groups, C–O carbohydrate moieties, and carboxyl groups.

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Polymer oxidation catalyst containing acidic functional groups

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19811237 ◽

1981 ◽

Vol 46 (5) ◽

pp. 1237-1247

Author(s):

Zdeněk Prokop ◽

Karel Setínek

Keyword(s):

Functional Groups ◽

Elevated Temperatures ◽

Redox Properties ◽

Oxidation Catalyst ◽

Carbon Clusters ◽

Oxidation Activity ◽

Redox Sites ◽

Styrene Divinylbenzene ◽

Proportional Decrease ◽

Polymer Oxidation

The catalyst containing redox sites in addition to acid functional groups was prepared by sulphonation of a macroporous chloromethylated styrene-divinylbenzene copolymer with concentrated sulphuric acid at elevated temperatures. Its activity was tested for the oxidation of 2-propanol by molecular oxygen at 120 °C and was found to be comparable to that of the iridium on carbon catalyst.Neutralisation of acid functional groups by alkali metal led to proportional decrease in the oxidation activity. The results of EPR spectroscopic study of these catalysts show that the redox properties of the polymer are caused by carbon clusters which are capable of electron exchange.

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Reactivity of Aliphatic and Phenolic Hydroxyl Groups in Kraft Lignin towards 4,4′ MDI

Molecules ◽

10.3390/molecules26082131 ◽

2021 ◽

Vol 26 (8) ◽

pp. 2131

Author(s):

Leonardo Dalseno Antonino ◽

Júlia Rocha Gouveia ◽

Rogério Ramos de Sousa Júnior ◽

Guilherme Elias Saltarelli Garcia ◽

Luara Carneiro Gobbo ◽

...

Keyword(s):

Experimental Work ◽

Chemical Structure ◽

31P Nmr ◽

Kraft Lignin ◽

Hydroxyl Group ◽

Hydroxyl Groups ◽

Diphenylmethane Diisocyanate ◽

Complex Chemical ◽

Heterogeneous Reactivity ◽

Phenolic Hydroxyl Groups

Several efforts have been dedicated to the development of lignin-based polyurethanes (PU) in recent years. The low and heterogeneous reactivity of lignin hydroxyl groups towards diisocyanates, arising from their highly complex chemical structure, limits the application of this biopolymer in PU synthesis. Besides the well-known differences in the reactivity of aliphatic and aromatic hydroxyl groups, experimental work in which the reactivity of both types of hydroxyl, especially the aromatic ones present in syringyl (S-unit), guaiacyl (G-unit), and p-hydroxyphenyl (H-unit) building units are considered and compared, is still lacking in the literature. In this work, the hydroxyl reactivity of two kraft lignin grades towards 4,4′-diphenylmethane diisocyanate (MDI) was investigated. 31P NMR allowed the monitoring of the reactivity of each hydroxyl group in the lignin structure. FTIR spectra revealed the evolution of peaks related to hydroxyl consumption and urethane formation. These results might support new PU developments, including the use of unmodified lignin and the synthesis of MDI-functionalized biopolymers or prepolymers.

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Mechanical Properties of Graphene Oxide Coupled by Multi-Physical Field: Grain Boundaries and Functional Groups

Crystals ◽

10.3390/cryst11010062 ◽

2021 ◽

Vol 11 (1) ◽

pp. 62

Author(s):

Xu Xu ◽

Zeping Zhang ◽

Wenjuan Yao

Keyword(s):

Mechanical Properties ◽

Graphene Oxide ◽

Grain Boundaries ◽

Functional Groups ◽

Oxygen Content ◽

Tensile Fracture ◽

Hydroxyl Groups ◽

Molecular Configuration ◽

Spatial Design ◽

Out Of Plane

Graphene and graphene oxide (GO) usually have grain boundaries (GBs) in the process of synthesis and preparation. Here, we “attach” GBs into GO, a new molecular configuration i.e., polycrystalline graphene oxide (PGO) is proposed. This paper aims to provide an insight into the stability and mechanical properties of PGO by using the molecular dynamics method. For this purpose, the “bottom-up” multi-structure-spatial design performance of PGO and the physical mechanism associated with the spatial structure in mixed dimensions (combination of sp2 and sp3) were studied. Also, the effect of defect coupling (GBs and functional groups) on the mechanical properties was revealed. Our results demonstrate that the existence of the GBs reduces the mechanical properties of PGO and show an “induction” role during the tensile fracture process. The presence of functional groups converts in-plane sp2 carbon atoms into out-of-plane sp3 hybrid carbons, causing uneven stress distribution. Moreover, the mechanical characteristics of PGO are very sensitive to the oxygen content of functional groups, which decrease with the increase of oxygen content. The weakening degree of epoxy groups is slightly greater than that of hydroxyl groups. Finally, we find that the mechanical properties of PGO will fall to the lowest values due to the defect coupling amplification mechanism when the functional groups are distributed at GBs.

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