Ozonation of a lignin-carbohydrate complex model compound of the benzyl ether type

2000 ◽  
Vol 46 (3) ◽  
pp. 263-265 ◽  
Author(s):  
Olov Karlsson ◽  
Tsutomu Ikeda ◽  
Takao Kishimoto ◽  
Kengo Magara ◽  
Yuji Matsumoto ◽  
...  
Keyword(s):  
Model Compound ◽  
Complex Model ◽  
Benzyl Ether ◽  
Carbohydrate Complex

Reactivity of a benzylic lignin-carbohydrate model compound during enzymatic dehydrogenative polymerisation of coniferyl alcohol

Holzforschung ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Kimiaki Shimizu ◽  
Yasuyuki Matsushita ◽  
Dan Aoki ◽  
Hayato Mitsuda ◽  
Kazuhiko Fukushima
Keyword(s):  
Mass Spectrometry ◽  
Model Compound ◽  
Degradation Products ◽  
Coniferyl Alcohol ◽  
Gas Chromatography Mass Spectrometry ◽  
Benzyl Ether ◽  
Model Compounds ◽  
Dimer Model ◽  
Carbohydrate Complex ◽  
Lignin Model

Abstract Lignin is thought to be covalently bound to carbohydrates like hemicellulose during biosynthesis to form a lignin-carbohydrate complex (LCC). However, successive polymerisation with monolignols after the formation of LCC has not yet been clarified. To investigate the reaction of LCC, its enzymatic dehydrogenative polymerisation was conducted using deuterium-labelled coniferyl alcohol and model compounds, i.e., a lignin model (β-O-4 dimer model) compound (LM) and an LCC model (benzyl ether type) compound (LCCM). The obtained polymers (DHPs) were methylated and subjected to thioacidolysis, and the degradation products were quantified by gas chromatography-mass spectrometry (GC-MS). The results showed that the amount of coniferyl alcohol connected to the LCCM via β-O-4 binding was almost the same as that bound to the LM. However, the amount of unreacted LCCM was larger than that of LM, suggesting that the LCCM is less likely to form condensed structures, i.e., 5-5, β-5, and 4-O-5 structures. This could be due to the steric hindrance of the carbohydrate at the benzylic position.

Co-Cracking of Bio-Oil Model Compound Mixture and Ethanol with Different Blending Ratios for Bio-Gasoline Production

2014 ◽  
Vol 986-987 ◽  
pp. 30-33
Author(s):  
Li Zhang ◽  
Qin Jie Cai ◽  
Shu Rong Wang
Keyword(s):  
Aromatic Hydrocarbons ◽  
Model Compound ◽  
Complex Model ◽  
Model Compounds ◽  
Conversion Yield ◽  
Yield And Quality ◽  
Bio Oil ◽  
Aliphatic And Aromatic Hydrocarbons ◽  
Reactant Conversion

Since the composition of crude bio-oil was complex, model compounds were usually used in the study of cracking to simulate the actual bio-oil. However, the cracking of pure model compound mixture generated an inferior oil phase which had a high content of oxygenated byproducts. When ethanol was adopted as the co-reactant, the reactant conversion, yield and quality of oil phase were obviously improved. The conversions of the reactants were 100% and the selectivity of the oil phase was 31.5wt% when the concentration of model compound mixture in the feed reached 30%. Meanwhile, the oil phase also had a superior quality which was entirely composed of aliphatic and aromatic hydrocarbons.

Three-coordinate binuclear copper(I) complex: model compound for the copper sites in deoxyhemocyanin and deoxytyrosinase

1982 ◽  
Vol 104 (19) ◽  
pp. 5240-5242 ◽  
Author(s):  
Kenneth D. Karlin ◽  
Yilma Gultneh ◽  
John P. Hutchinson ◽  
Jon Zubieta
Keyword(s):  
Model Compound ◽  
Complex Model ◽  
Binuclear Copper ◽  
Copper Sites

scholarly journals Elucidation of the Structure of Lignin-Carbohydrate Complexes in Ginkgo CW-DHP by 13C-2H Dual Isotope Tracer

Molecules ◽  
2021 ◽  
Vol 26 (19) ◽  
pp. 5740
Author(s):  
Kai Zhang ◽  
Yanchao Liu ◽  
Sheng Cui ◽  
Yimin Xie
Keyword(s):  
13C Nmr ◽  
Type I ◽  
Benzyl Ether ◽  
Dual Isotope ◽  
Isotope Tracer ◽  
Carbohydrate Complex ◽  
Normal Metabolism ◽  
Cambial Cells ◽  
Dehydrogenation Polymers ◽  
Differential Spectroscopy

To elucidate the chemical linkages between lignin and carbohydrates in ginkgo cell walls, 13C-2H-enriched cell wall-dehydrogenation polymers (CW-DHP) were selectively prepared with cambial tissue from Ginkgo biloba L. by feeding D-glucose-[6-2H2], coniferin-[α-13C], and phenylalanine ammonia-lyase (PAL) inhibitor. The abundant detection of 13C and 2H confirmed that D-glucose-[6-2H2] and coniferin-[α-13C] were involved in the normal metabolism of ginkgo cambial cells that had been effectively labelled with dual isotopes. In the ginkgo CW-DHP, ketal and ether linkages were formed between the C-α of lignin side chains and carbohydrates, as revealed by solid state CP/MAS 13C-NMR differential spectroscopy. Furthermore, the DMSO/TBAH ionic liquids system was used to fractionate the ball-milled CW-DHP into three lignin-carbohydrate complex (LCC) fractions: glucan–lignin complex (GL), glucomannan–lignin complex (GML), and xylan–lignin complex (XL). The XRD determination indicated that the cellulose type I of the GL was converted into cellulose type II during the separation process. The molecular weight was in the order of Ac-GL > Ac-GML > XL. The 13C-NMR and 1H-NMR differential spectroscopy of 13C-2H-enriched GL fraction indicated that lignin was linked with cellulose C-6 by benzyl ether linkages. It was also found that there were benzyl ether linkages between the lignin side chain C-α and glucomannan C-6 in the 13C-2H-enriched GML fraction. The formation of ketal linkages between the C-α of lignin and xylan was confirmed in the 13C-2H-enriched XL fraction.

Degradation of Model Compounds for Cellulose and Lignocellulosic Pulp during Ozonation in Aqueous Solution

Holzforschung ◽  
2000 ◽  
Vol 54 (4) ◽  
pp. 397-406 ◽  
Author(s):  
Carola Olkkonen ◽  
Henrik Tylli ◽  
Ingegerd Forsskåhl ◽  
Agneta Fuhrmann ◽  
Tiina Hausalo ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
High Performance ◽  
Room Temperature ◽  
Model Compound ◽  
The Other ◽  
Model Compounds ◽  
Freeze Dried ◽  
Carbohydrate Complex ◽  
Ozonation Time ◽  
Acidic Compounds

Summary Ozonations of methylpyranosides, as model compounds for cellulose, were performed in unbuffered aqueous solution at room temperature. The degradation of the pyranosides was followed spectrophotometrically and with high-performance liquid chromatography (HPLC) as a function of ozonation time. The substrates studied were the α- and β-anomers of methyl-D-glucopyranoside, methyl-D-mannopyranoside and methyl-D-xylopyranoside. Methyl-α-D-xylopyranoside degraded more slowly than the other compounds, whereas the rate of degradation was fastest for methyl-β-D-mannopyranoside. In general the degradation of the α-anomers was slower than that of the corresponding β-anomers. HPLC and gas chromatography—mass selective (GC-MS) analyses of the ozonated glucopyranoside samples showed that monosaccharides, lactones, furanosides and acidic compounds are formed during ozonation. A lignin-carbohydrate complex (LCC), containing a D-xylose unit connected to an aromatic part through a βglycosidic bond, was used as a model compound for lignocellulosic pulp. The degradation of this compound during ozonation was also investigated. The results from UV analyses showed that the reaction was extremely fast at the beginning and that the degradation of benzene structures in the lignin mimicking part of the LCC was very rapid. The degradation of the carbohydrate part was slower. This suggests that lignin provides some protection for the cellulose in lignin-containing pulps against attack by ozone. IR and NMR analyses of the freeze-dried ozonated LCC samples showed further that C=O structures are produced during ozonation.

Visible Light-Mediated Oxidative Debenzylation

2020 ◽  
Author(s):  
Cristian Cavedon ◽  
Eric T. Sletten ◽  
Amiera Madani ◽  
Olaf Niemeyer ◽  
Peter H. Seeberger ◽  
...  
Keyword(s):  
Reaction Time ◽  
Visible Light ◽  
Functional Groups ◽  
Continuous Flow ◽  
Protecting Groups ◽  
Benzyl Ether ◽  
Complex Molecules ◽  
Protective Groups ◽  
Benzyl Ethers ◽  
Harsh Conditions

Protecting groups are key in the synthesis of complex molecules such as carbohydrates to distinguish functional groups of similar reactivity. The harsh conditions required to cleave stable benzyl ether protective groups are not compatible with many other protective and functional groups. The mild, visible light-mediated debenzylation disclosed here renders benzyl ethers orthogonal protective groups. Key to success is the use of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as stoichiometric or catalytic photooxidant such that benzyl ethers can be cleaved in the presence of azides, alkenes, and alkynes. The reaction time for this transformation can be reduced from hours to minutes in continuous flow. <br>

Power Experimental Optimization of Horizontal Axis Wind Turbine

2020 ◽  
Vol 13 (3) ◽  
pp. 438-443
Author(s):  
Sadek Ameziane ◽  
Abdesselem Chikhi ◽  
Mohammed Salah Aggouner
Keyword(s):  
Wind Turbine ◽  
Vertical Axis ◽  
Energy System ◽  
Spatial Filter ◽  
Complex Model ◽  
Vertical Axis Wind Turbine ◽  
Horizontal Axis Wind Turbine ◽  
Detailed Model ◽  
Continuous Current ◽  
Mechanical Sensors

Background: The presented article is a contribution to the realization of a wind emulator based on a continuous-current machine. The development of this topic focuses on the modeling of a vertical axis wind turbine, a DC motor with independent excitation and its control via a chopper. Methods: To carry out this work, we have studied and designed the electronic and mechanical sensors as well as a command implemented on the dSPACE DS1103 system. Results: The main purpose of this work is related, on one hand, to the control of the motor turbine by imposing the wind profile and on the other hand generate the command of the implanted MPPT. The experimental results obtained showed the great performances which characterize this improved wind energy system. Conclusion: Finally, a wind turbine with variable speed is a system having a complex model; however, a detailed model of the interaction between the wind and the aero-turbine is useful to understand certain phenomena such as rotational sampling or the spatial filter.

Sign in / Sign up

Export Citation Format

Share Document