scholarly journals Structural Characterization of Lignin and Its Degradation Products with Spectroscopic Methods

2017 ◽  
Vol 2017 ◽  
pp. 1-15 ◽  
Author(s):  
Yao Lu ◽  
Yong-Chao Lu ◽  
Hong-Qin Hu ◽  
Feng-Jin Xie ◽  
Xian-Yong Wei ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Degradation Products ◽  
2D Nmr ◽  
Spectroscopic Methods ◽  
Spectroscopic Techniques ◽  
Qualitative And Quantitative ◽  
High Efficient ◽  
Nmr Techniques ◽  
Lignin Structure

Lignin is highly branched phenolic polymer and accounts 15–30% by weight of lignocellulosic biomass (LCBM). The acceptable molecular structure of lignin is composed with three main constituents linked by different linkages. However, the structure of lignin varies significantly according to the type of LCBM, and the composition of lignin strongly depends on the degradation process. Thus, the elucidation of structural features of lignin is important for the utilization of lignin in high efficient ways. Up to date, degradation of lignin with destructive methods is the main path for the analysis of molecular structure of lignin. Spectroscopic techniques can provide qualitative and quantitative information on functional groups and linkages of constituents in lignin as well as the degradation products. In this review, recent progresses on lignin degradation were presented and compared. Various spectroscopic methods, such as ultraviolet spectroscopy, Fourier-transformed infrared spectroscopy, Raman spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy, for the characterization of structural and compositional features of lignin were summarized. Various NMR techniques, such as 1H, 13C, 19F, and 31P, as well as 2D NMR, were highlighted for the comprehensive investigation of lignin structure. Quantitative 13C NMR and various 2D NMR techniques provide both qualitative and quantitative results on the detailed lignin structure and composition produced from various processes which proved to be ideal methods in practice.

scholarly journals Structural characterization of 13C-enriched humins and alkali-treated 13C humins by 2D solid-state NMR

2015 ◽  
Vol 17 (8) ◽  
pp. 4383-4392 ◽  
Author(s):  
Ilona van Zandvoort ◽  
Eline J. Koers ◽  
Markus Weingarth ◽  
Pieter C. A. Bruijnincx ◽  
Marc Baldus ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Solid State ◽  
Structural Characterization ◽  
Solid State Nmr ◽  
2D Nmr ◽  
Nmr Techniques ◽  
By Products

Complementary (2D) NMR techniques provide new insights into the molecular structure of humin by-products.

scholarly journals Pentacyclic Triterpenoids from Maytenus cuzcoina

2017 ◽  
Vol 12 (5) ◽  
pp. 1934578X1701200
Author(s):  
Carolina P. Reyes ◽  
Ignacio A. Jiménez ◽  
Isabel L. Bazzocchi
Keyword(s):  
2D Nmr ◽  
Bark Extract ◽  
Phytochemical Analysis ◽  
Spectroscopic Methods ◽  
Root Bark ◽  
Pentacyclic Triterpenoids ◽  
Isolation And Characterization ◽  
Nmr Techniques ◽  
First Time

Phytochemical analysis of the root bark extract of Maytenus cuzcoina (Celastraceae) led to the isolation and characterization of sixteen triterpenoids with a 6/6/6/6/6 pentacyclic system, including the new 22α-hydroxy-29-methoxy-3β-tetradecanoate-olean-12-ene, and 3β,24β-epoxy-29-methoxy-2α,3α,6α-trihydroxy- D:A-friedelane that is reported for the first time as a natural product. This is the first instance of the isolation of a tetradecanoate triterpene ester from a Celastraceae species. The structures were elucidated on the basis of spectrometric and spectroscopic methods, including 1D and 2D NMR techniques.

Synthesis and Characterization of Potential and Degraded Impurities of Regadenoson

2020 ◽  
Vol 16 (8) ◽  
pp. 1130-1139
Author(s):  
Singaram Sathiyanarayanan ◽  
Chidambaram Subramanian Venkatesan ◽  
Senthamaraikannan Kabilan
Keyword(s):  
Mass Spectra ◽  
Degradation Products ◽  
Hplc Method ◽  
Forced Degradation ◽  
Spectroscopic Techniques ◽  
A2a Adenosine Receptor ◽  
Degradation Study ◽  
Related Substances ◽  
Adenosine Receptor Agonist

Background: Regadenoson is an A2A adenosine receptor agonist that is a coronary vasodilator and commonly used as a pharmacologic cardiac stressing agents. Methods: HPLC method was used for the analysis of related substances. The degraded impurities during the process were isolated and characterized by IR, Mass and NMR spectral analysis. Results: Forced degradation study of regadenoson under conditions of hydrolysis (neutral, acidic and alkaline) and oxidations suggested in the ICH Q1A(R2) was accomplished. The drug showed significant degradation under all the above conditions. On the whole, five novel degradation products were found under diverse conditions along with process related impurities which were not reported earlier. Conclusion: All the degradation products were well characterized by using advanced spectroscopic techniques like IR, 1H NMR, 13C NMR and Mass spectra. The identification of these impurities will be productive for the quality control during the production and stability behavior of the regadenoson drug substance.

Flavon- and Flavonolglycosides from Achillea pannonica Scheele

2001 ◽  
Vol 56 (7-8) ◽  
pp. 521-525 ◽  
Author(s):  
Denata Kasaj ◽  
Liselotte Krenn ◽  
Sonja Prinz ◽  
Antje Hüfner ◽  
Shi Shan Yuc ◽  
...  
Keyword(s):  
Methanolic Extract ◽  
2D Nmr ◽  
Flavonoid Glycosides ◽  
Spectroscopic Methods ◽  
Esi Ms ◽  
Aerial Parts ◽  
Nmr Techniques ◽  
Chemotaxonomic Study ◽  
First Time ◽  
C Nmr

The detailed investigation of a methanolic extract of aerial parts of Achillea pannonica SCHEELE. within a chemotaxonomic study led to the isolation of 6 flavonoid glycosides. Besides rutin, apigenin-7-O-glucopyranoside, luteolin-7-O-glucopyranoside, apigenin-7-O-rutinoside and acacetin-7-O-rutinoside, an unusual flavondiglucoside was isolated. Its structure was established by UV, 1HNMR and 13C NMR spectroscopic methods including 2D-NMR techniques and ESI-MS as luteolin-7,4′-O-β-diglucoside. This substance is reported for the first time in the genus Achillea. Chemotaxonomic aspects are discussed briefly

scholarly journals Isolation and Structural Characterization of Degradation Products of Aceclofenac by HPLC, HRMS and 2D NMR

2019 ◽  
Vol 31 (4) ◽  
pp. 851-854
Author(s):  
Santhosh Guduru ◽  
V.V.S.R.N. Anji Karun Mutha ◽  
B. Vijayabhaskar ◽  
Muralidharan Kaliyaperumal ◽  
Raghu Babu Korupolu ◽  
...  
Keyword(s):  
Degradation Product ◽  
Degradation Products ◽  
Acid Stress ◽  
2D Nmr ◽  
Stress Conditions ◽  
Preparative Hplc ◽  
Mass Spectral ◽  
2D Nmr Spectra ◽  
The Stability

The stability of aceclofenac under stress conditions was assessed to identify the degradation products. So, it was subjected to stress conditions like acid, base and oxidation, according to ICH guideline Q1A (R2). One degradation product formed when the drug was subjected to acid stress. Three degradation products were formed during the basic stress condition. The drug substance was found to be stable to oxidative stress. The degradants formed during the stress were separated on a C-18 column using gradient preparative HPLC elution. The only product (DP-2) formed during the acid stress and this one is same as of one of the three degradation products (DP-1, DP-2, DP-3) were formed during base stress. 1D and 2D NMR spectra and mass spectral analysis supported the proposed structures for the products. The products DP-2 and DP-3 have been reported earlier but this is the first report of product DP-1 as a degradation product of aceclofenac.

Characterization of Process Induced Contamination and Residues on Semiconductor Components Via FTIR and Raman Microanalysis

2001 ◽  
Vol 7 (S2) ◽  
pp. 152-153
Author(s):  
H. Gotts
Keyword(s):  
Molecular Structure ◽  
Yield Enhancement ◽  
Spectroscopic Techniques ◽  
Bulk Materials ◽  
Scanning Calorimetry ◽  
Vis Spectroscopy ◽  
Classical Technique ◽  
Raman Microprobe ◽  
Scanning Electron

FTIR and Raman microanalysis may be used as a powerful combination to determine the identity, and hence infer the source, of contaminant particles which diminish yields of semiconductor components and devices. The complimentarity of these techniques arises from the underlying spectroscopic selection rules.Vibrational spectroscopic techniques are commonly used to characterize the molecular structure of bulk organic materials. These bulk materials typically represent purified fractions of components which may be further investigated with various classical instrumental techniques such as Differential Scanning Calorimetry (DSC), Nuclear Magnetic Resonance (NMR) spectroscopy, UV-Vis spectroscopy. However, these classical technique may have limited value for the interrogation of small impure particles or materials of limited quantity(ng.).Elemental techniques such as Scanning Electron Microscopy coupled to Energy Dispersive Spectroscopy are enhanced by the specificity of FTIR Microprobe Spectroscopy and Raman Microprobe Spectroscopy which are now used in process laboratories to characterize and identify particulate and thin film residues with the intent of device yield enhancement.

scholarly journals Synthesis and Characterization of Low-Cost Cresol-Based Benzoxazine Resins as Potential Binders in Abrasive Composites

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 2995
Author(s):  
Artur Jamrozik ◽  
Mateusz Barczewski ◽  
Grzegorz Framski ◽  
Daniel Baranowski ◽  
Paulina Jakubowska ◽  
...  
Keyword(s):  
Low Cost ◽  
2D Nmr ◽  
Additional Analysis ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry ◽  
Voc Emission ◽  
Chemical Structures ◽  
Oxazine Ring ◽  
Nmr Techniques

A series of cresol-based benzoxazines were synthesized for potential application as a polymer matrix in abrasive composites. The chemical structures of the obtained benzoxazine resins were investigated in detail using Fourier transform infrared spectroscopy (FTIR) and hydrogen-1 as well as carbon-13 nuclear magnetic resonance spectroscopy (1H NMR, 13C NMR) with an additional analysis using two-dimensional NMR techniques (2D NMR 1H-1H COSY, 1H-13C gHSQC and gHMBC). Structural analysis confirmed the presence of vibrations of -O-C-N- at ~950 cm−1 wavenumber, characteristic for an oxazine ring. The thermal properties of benzoxazine monomers were examined using differential scanning calorimetry (DSC) analysis. The polymerization enthalpy varied from 143.2 J/g to 287.8 J/g. Thermal stability of cresol-based benzoxazines was determined using thermogravimetry (TGA) analysis with additional analysis of the amount of volatile organic compounds (VOC) emitted from the synthesized benzoxazines during their crosslinking by static headspace coupled with gas chromatography technique (HS-GC). The amount of residual mass significantly differed between all synthesized polybenzoxazines in the range from 8.4% to 21.2%. The total VOC emission for benzoxazines decreased by 46–77% in reference to a conventional phenolic binder. The efficiency of abrasive composites with the benzoxazine matrix was evaluated based on abrasion tests. Performed analyses confirmed successful synthesis and proper chemical structure of cresol-based benzoxazines. All the experiments indicated that benzoxazines based on different cresol isomers significantly differ from each other. Good thermal performance and stability of the abrasive composites with the polybenzoxazine matrix and significantly lower VOC emission allow us to state that benzoxazines can be a promising and valuable alternative to the phenolics and a new path for the development of modern, eco-friendly abrasives.

Glycosides from Cephalaria Species

2010 ◽  
Vol 65 (11) ◽  
pp. 1384-1392 ◽  
Author(s):  
Erkan Halay ◽  
Süheyla Kırmızıgül
Keyword(s):  
Mass Spectrometry ◽  
Oleanolic Acid ◽  
2D Nmr ◽  
Spectroscopic Methods ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Nmr Techniques ◽  
Basic Hydrolysis ◽  
Hydrolysis Of ◽  
Chemical Evidence

Three novel triterpene glycosides (1 - 3), namely lycicoside I, II and cilicicoside I, were isolated from two different Cephalaria (Dipsacaceae) species along with one known oleanane- and one iridoit- type of glycoside. The structures of these compounds were established as 3-O-[β -D-glucopyranosyl( 1→3)-α-L-rhamnopyranosyl(1→4)-β -D-xylopyranosyl(1→4)-β -D-xylopyranosyl]-28-O-[β -Dglucopyranosyl( 1→6)-β -D-glucopyranosyl]-oleanolic acid (1), 3-O-[β -D-xylopyranosyl(1→3)-α- L-rhamnopyranosyl(1→4)-β -D-xylopyranosyl]-28-O-[β -D-glucopyranosyl]-oleanolic acid (2) from Cephalaria lycica Matthew and 3-O-{β -D-glucopyranosyl(1→4)-β -D-xylopyranosyl(1→3)-α-Lrhamnopyranosyl( 1→2)-[β -D-glucopyranosyl(1→3)]-α -L-rhamnopyranosyl}-28-O-[β -D-glucopyranosyl( 1→6)-β -D-glucopyranosyl]-hederagenin (3) from Cephalaria cilicica Boiss. & Kotschy, on the basis of spectroscopic methods (1D and 2D NMR techniques, mass spectrometry) and chemical evidence. In addition, three new prosapogenins, 1B - 3B, were obtained from the basic hydrolysis of 1 - 3. The antimicrobial activity of 1 - 3 was tested against some Gram-positive and Gram-negative bacteria strains.

scholarly journals Isolation and Characterization of Two New Antimicrobial Acids from Quercus incana (Bluejack Oak)

2018 ◽  
Vol 2018 ◽  
pp. 1-5
Author(s):  
Rizwana Sarwar ◽  
Umar Farooq ◽  
Sadia Naz ◽  
Nadia Riaz ◽  
Syed Majid Bukhari ◽  
...  
Keyword(s):  
Ethyl Acetate Fraction ◽  
Structural Formula ◽  
2D Nmr ◽  
Spectroscopic Technique ◽  
Pentanoic Acid ◽  
One Dimensional ◽  
Isolation And Characterization ◽  
Nmr Techniques ◽  
New Compounds

Two new compounds [1-2] were purified from ethyl acetate fraction of Quercus incana. The structure of these compounds is mainly established by using advanced spectroscopic technique such as UV, IR, one-dimensional (ID) and two-dimensional (2D) NMR techniques, and EI mass. The structural formula was deduced to be 4-hydroxydecanoic acid [1] and 4-hydroxy-3-(hydroxymethyl) pentanoic acid [2]. Both isolated compounds were tested for their antimicrobial potential and showed promising antifungal activity against Aspergillus niger and Aspergillus flavus.

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