scholarly journals Effect of hydrothermal treatment on the carbon structure of Inner Mongolia lignite

2020 ◽  
Vol 7 (3) ◽  
pp. 493-503
Author(s):  
Peng Liu ◽  
Dexiang Zhang
Keyword(s):  
Hydrothermal Treatment ◽  
Functional Groups ◽  
Inner Mongolia ◽  
Hydrogen Transfer ◽  
Covalent Bond ◽  
Decomposition Reaction ◽  
Resonance Spectroscopy ◽  
Free Phenol ◽  
Subsequent Behavior ◽  
Curve Fitting Method

Abstract Understanding the structural properties of lignite during hydrothermal treatment would aid in predicting the subsequent behavior of coal during the pyrolysis, liquefaction, and gasification processes. Here, hydrothermal treatment of Inner Mongolia lignite (IM) was carried out in a lab autoclave. The distribution of carbon in the lignite was monitored via solid 13C nuclear magnetic resonance spectroscopy, and the functional groups of oxygen in lignite were determined by Fourier transform infrared spectroscopy. The curve-fitting method was used to calculate the content of the functional groups quantitatively. The results show that hydrothermal treatment is an effective method for upgrading the lignite. The side chains of the aromatic ring in lignite are altered, while the main macromolecular structure remains nearly the same. The hydrothermal treatment of IM could be divided into three temperature-dependent stages. The first stage (< 493 K) is the decomposition reaction of oxygen functional groups, where the O/C ratio decreases from 0.203 in raw IM to 0.185 for the IM treated at 493 K. In the second stage (493–533 K), hydrolysis of functional groups and hydrogen transfer between water and lignite occur. Here, the ratio of methylene to methyl increases from 0.871 in IM-493 to 1.241 for IM-533, and the content of quinone generates from the condensation of free phenol increased. The third stage (> 533 K) involves breakage of the covalent bond, and the content of CH4 and CO in the emission gas clearly increase.

scholarly journals Study of the biologically active acyclic ureas by nuclear magnetic resonance

2020 ◽  
Vol 100 (4) ◽  
pp. 60-74
Author(s):  
А.А. Bakibaev ◽  
◽  
М.Zh. Sadvakassova ◽  
V.S. Malkov ◽  
R.Sh. Еrkasov ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Functional Groups ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Biologically Active ◽  
Resonance Spectroscopy ◽  
13C Nmr Spectra ◽  
Nuclear Magnetic

A wide variety of acyclic ureas comprising alkyl, arylalkyl, acyl, and aryl functional groups are investigated by nuclear magnetic resonance spectroscopy. In general, spectral characteristics of more than 130 substances based on acyclic ureas dissolved in deuterated dimethyl sulfoxide at room temperature are studied. The re-sults obtained based on the studies of 1H and 13C NMR spectra of urea and its N-alkyl-, N-arylalkyl-, N-aryl- and 1,3-diaryl derivatives are presented, and the effect of these functional groups on the chemical shifts in carbonyl and amide moieties in acyclic urea derivatives is discussed. An introduction of any type of substitu-ent (electron-withdrawing or electron-donating) into urea molecule is stated to result in a strong upfield shift in 13C NMR spectra relatively to unsubstituted urea. A strong sensitivity of NH protons to the presence of acyl and aryl groups in nuclear magnetic resonance spectra is pointed out. In some cases, qualitative depend-encies between the chemical shifts in the NMR spectra and the structure of the studied acyclic ureas are re-vealed. A summary of the results on chemical shifts in the NMR spectra of the investigated substances allows determining the ranges of chemical shift variations of the key protons and carbon atoms in acyclic ureas. The literature describing the synthesis procedures are provided. The results obtained significantly expand the methods of reliable identification of biologically active acyclic ureas and their metabolites that makes it promising to use NMR spectroscopy both in biochemistry and in clinical practice.

scholarly journals Structural Characterization of Graphene Oxide: Surface Functional Groups and Fractionated Oxidative Debris

Nanomaterials ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 1180 ◽  
Author(s):  
Elvin Aliyev ◽  
Volkan Filiz ◽  
Muntazim M. Khan ◽  
Young Joo Lee ◽  
Clarissa Abetz ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Graphene Oxide ◽  
Functional Groups ◽  
Structural Model ◽  
Oxide Surface ◽  
Resonance Spectroscopy ◽  
X Ray Diffraction ◽  
Surface Functional Groups ◽  
X Ray ◽  
Transmission Electron

The purpose of this work is the structural analysis of graphene oxide (GO) and by means of a new structural model to answer the questions arising from the Lerf–Klinowski and the Lee structural models. Surface functional groups of GO layers and the oxidative debris (OD) stacked on them were investigated after OD was extracted. Analysis was performed successfully using Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-Vis), X-ray photoemission spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), Raman spectroscopy, solid-state nuclear magnetic resonance spectroscopy (SSNMR), standardized Boehm potentiometric titration analysis, elemental analysis, X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The analysis showed that graphene oxide layers, as well as oxidative debris contain different functional groups such as phenolic –OH, ketone, lactone, carboxyl, quinone and epoxy. Based on these results, a new structural model for GO layers is proposed, which covers all spectroscopic data and explains the presence of the other oxygen functionalities besides carboxyl, phenolic –OH and epoxy groups.

Effect of Acid on Surface Hydroxyl Groups on Kaolinite and Montmorillonite

2018 ◽  
Vol 232 (3) ◽  
pp. 409-430 ◽  
Author(s):  
Sarah K. Sihvonen ◽  
Kelly A. Murphy ◽  
Nancy M. Washton ◽  
Muhammad Bilal Altaf ◽  
Karl T. Mueller ◽  
...  
Keyword(s):  
Functional Groups ◽  
Acid Treatment ◽  
Atmospheric Transport ◽  
Magic Angle Spinning ◽  
Resonance Spectroscopy ◽  
Hydroxyl Groups ◽  
Magic Angle ◽  
Surface Hydroxyl ◽  
Surface Hydroxyl Groups ◽  
Angle Spinning

AbstractMineral dust aerosol participates in heterogeneous chemistry in the atmosphere. In particular, the hydroxyl groups on the surface of aluminosilicate clay minerals are important for heterogeneous atmospheric processes. These functional groups may be altered by acidic processing during atmospheric transport. In this study, we exposed kaolinite (KGa-1b) and montmorillonite (STx-1b) to aqueous sulfuric acid and then rinsed the soluble reactants and products off in order to explore changes to functional groups on the mineral surface. To quantify the changes due to acid treatment of edge hydroxyl groups, we use19F magic angle spinning nuclear magnetic resonance spectroscopy and a probe molecule, 3,3,3-trifluoropropyldimethylchlorosilane. We find that the edge hydroxyl groups (OH) increase in both number and density with acid treatment. Chemical reactions in the atmosphere may be impacted by the increase in OH at the mineral edge.

Synthesis of Polycationic Aza-Belted Heterocyclic Iodomethane Salts

2019 ◽  
Vol 11 (11) ◽  
pp. 1134-1141
Author(s):  
Yan-Yan Wang ◽  
Tuan-Jie Wang ◽  
Juan Chen ◽  
Chao-Yang Wang ◽  
Jing Zhu
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Nuclear Magnetic Resonance Spectroscopy ◽  
Functional Groups ◽  
Chemical Shifts ◽  
Resonance Spectroscopy ◽  
Reaction Conditions ◽  
13C Nuclear Magnetic Resonance ◽  
Judicious Choice

Novel belt shapes of a diazabicyclo[n,n,5.5]alkane center combined with double iodomethane salts were prepared in two steps by a reaction of phenylethylamine or 3,4-dimethoxyphenylethylamine with ortho-bis(chloromethyl)benzenes. The syntheses and characteristics of these polycationic systems containing aza-belt rings are described. Judicious choice of the reaction conditions allowed these polycationic heterocycles to be generated in good yields, and 1H and 13C nuclear magnetic resonance spectroscopy revealed a change in chemical shifts caused by interactions between the functional groups.

scholarly journals Purity Specifications of Constituents of Cinnamon Essential Oil by Fourier Transformed Infrared Spectroscopy Analysis

2017 ◽  
Vol 5 (02) ◽  
pp. 36-40
Author(s):  
Hicham Boughendjioua ◽  
Nadia Amoura ◽  
Zahra Boughendjioua
Keyword(s):  
Mass Spectrometry ◽  
Nuclear Magnetic Resonance ◽  
Infrared Spectroscopy ◽  
Magnetic Resonance ◽  
Volatile Compounds ◽  
Functional Groups ◽  
Organic Molecules ◽  
Resonance Spectroscopy ◽  
Fourier Transformed Infrared Spectroscopy ◽  
Nuclear Magnetic

Three main tools are used to determine the structures of organic molecules. These tools are infrared (IR) spectroscopy, mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy. Infrared Spectroscopy (IR), Mass Spectrometry (MS) and Nuclear Magnetic Resonance Spectroscopy (NMR). Organic molecules absorb light (infrared, ultraviolet, etc.) at particular wavelengths based on different vibrational modes unique to the specific functional groups and structural features. In the present study, the volatile compounds of Cinnamon (Cinnamomum zeylanicum) were detected and identified by Fourier Transformed Infrared Spectroscopy (FTIR) analysis. FTIR allowed us to identify 10 volatile compounds and indicated than the functional groups of the essential oils are CHx, C=C and C=O.

Solvent Effect on Bond Dissociation Enthalpy (BDE) of Tetrahydrocurcumin: A Theoretical Study

2019 ◽  
Vol 966 ◽  
pp. 215-221
Author(s):  
Lusia Silfia Pulo Boli ◽  
Nufida Dwi Aisyah ◽  
Vera Khoirunisa ◽  
Heni Rachmawati ◽  
Hermawan Kresno Dipojono ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Solvent Effect ◽  
Functional Groups ◽  
Density Functional ◽  
Hydrogen Transfer ◽  
Bond Dissociation Enthalpy ◽  
Polar Medium ◽  
Bond Dissociation ◽  
Dissociation Enthalpy ◽  
Frequency Calculation

Solvent effect on bond dissociation enthalpy (BDE) of different functional groups of tetrahydrocurcumin is investigated. This is to evaluate how the polarity of a medium affect BDE and to clarify which functional groups hold the key role in its antioxidant activity through hydrogen transfer. We occupy density functional theory to calculate BDE through geometrical optimization and frequency calculation at six sites of tetrahydrocurcumin in water, methanol and chloroform solvents. The solvents represent polar and non-polar medium. Our result shows that BDE is lower in non-polar medium and hydrogen transfer is favored in this medium. A phenolic group is responsible for the antioxidant activity of tetrahydrocurcumin.

Chemie an starren Grenzflächen, 7 [1] Ausgewählte Beispiele der chemischen Grenzflächenmodifizierung von Aerosil / Chemistry at Rigid Surfaces, 7 [1] Selected Examples of the Chemical Surface Modification of Aerosil

1987 ◽  
Vol 42 (5) ◽  
pp. 643-660 ◽  
Author(s):  
Leopold Horner ◽  
Hans Ziegler
Keyword(s):  
Phosphoric Acid ◽  
Functional Groups ◽  
Carbonic Acid ◽  
Covalent Bond ◽  
Chemical Surface ◽  
Usual Manner ◽  
Primary Amino ◽  
Covalently Linked ◽  
Acid Anhydrides ◽  
Rigid Surfaces

Aminoaerosil containing primary amino end groups is obtained according (1) by reaction of aerosil with γ-triethoxysilylpropyl amine (Table II).The NH2-anchor groups are acylated in the usual manner: carbonic acid anhydrides, acid chlorides and acid azides and by application of the carbodiimide method (Table III). Optically active groups and phosphoric acid diestergroups are covalently linked with the surface of aerosil according (2) and (3). Aminoaerosil reacts with vinylsulfones as anchor groups of dyes (Remazol- Dyes) producing a covalent bond according (6).Functional groups linked to the surface of aerosil react “normal” (with respect to homogenous solutions) with group specific reagents. Examples: bromination, ozonization of C-C double bonds, hydrolysis of phosphoric acid esteramidates and surface bound chloroamine-T groups. "Interparticular" reactions of modified aerosil are not observed. But aerosil with electroactive groups are electroreduced using Hg- or Pb-electrodes.The optical induction of the catalytic hydrogenation of prochiral defines using palladium deposited on chiral modified aerosil surfaces is low (ca. 1%).Some analytical methods are presented, which are recommended for the determination of the amount of functional groups bound to the surface.

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