Autohydrolysis of aspen milled wood lignin

1980 ◽  
Vol 58 (7) ◽  
pp. 669-676 ◽  
Author(s):  
Jairo H. Lora ◽  
Morris Wayman
Keyword(s):  
Molecular Weight ◽  
Populus Tremuloides ◽  
Soluble Fraction ◽  
Gel Permeation Chromatography ◽  
Insoluble Fraction ◽  
Low Molecular Weight ◽  
Milled Wood Lignin ◽  
Insoluble Material ◽  
Initial Generation ◽  
Insoluble Product

In order to obtain further understanding of the nature of lignin reactions during autocatalysed hydrolysis (autohydrolysis) of wood, milled wood lignin (MWL) was isolated from aspen (Populus tremuloides) and treated under autohydrolysis conditions. By this means reactions of the lignin itself could be distinguished from those taking place between lignin and the carbohydrate or other components of the wood. The material after the reaction was separated into a dioxane insoluble fraction (DI), a dioxane soluble but ether insoluble fraction (DSEI), and an ether soluble fraction (ES). Studies were carried out on the DI and DSEI fractions; no direct study was made of the small ES fraction.The formation of DI material increased linearly during the first 7.5 min at 170 °C and then levelled off. At the same time DSEI decreased and then levelled off. Gel permeation chromatography of the DSEI fraction suggested that during autohydrolysis there is an initial generation of low molecular weight fragments which recombine to form first a high molecular weight soluble fraction and from this the insoluble product. The DSEI fraction contained increased conjugated and unconjugated keto groups. Carboxylic acids were also detected; they have been attributed to the reincorporation of low molecular weight aromatic acids generated by the hydrolysis of the corresponding esters. The dioxane insoluble (DI) fraction had fewer unconjugated keto groups than the DSEI fraction, indicating that these groups participated in the condensation reactions leading to the formation of insoluble material. These probably involve position 6 of the aromatic ring.

scholarly journals Characterisation of Sequential Solvent Fractionation and Base-catalysed Depolymerisation of Treated Alkali Lignin

BioResources ◽  
2015 ◽  
Vol 10 (3) ◽  
pp. 4137-4151 ◽  
Author(s):  
Aikfei Ang ◽  
Zaidon Ashaari ◽  
Edi Suhaimi Bakar ◽  
Nor Azowa Ibrahim
Keyword(s):  
Molecular Weight ◽  
Chemical Structure ◽  
Average Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Solubility Parameters ◽  
Low Molecular Weight ◽  
Sequential Fractionation ◽  
Weight Average Molecular Weight ◽  
Solvent Fractionation ◽  
Alkali Lignin

An alkali lignin (OL) with a weight-average molecular weight (Mw) of 11646 g/mol was used to prepare low-molecular weight lignin for resin synthesis. The low-molecular weight lignin feedstock was obtained via base-catalysed depolymerisation (BCD) treatments at different combined severity factors. Sequential fractionation of the OL and BCD-treated lignins using organic solvents with different Hildebrand solubility parameters were used to alter the homogeneity of the OL. The yield and properties of OL itself and OL and BCD-treated OL dissolved in propan-1-ol (F1), ethanol (F2), and methanol (F3) were determined. Regardless of the treatment applied, a small amount of OL was dissolved in F1 and F2. The BCD treatment did not increase the yield of F1 but did increase the yields of F2 and F3. Gel permeation chromatography (GPC) showed that the repolymerization reaction occurred in F3 for all BCD-treated OL, so these lignins were not suitable for use as feedstocks for resin production. The GPC, 13Carbon-nuclear magnetic resonance, and Fourier transform infrared spectroscopy analyses confirmed that the F3 in OL exhibited the optimum yield, molecular weight distribution, and chemical structure suitable for use as feedstocks for resin synthesis.

Fractionation of Rubber

1941 ◽  
Vol 14 (1) ◽  
pp. 1-14 ◽  
Author(s):  
George F. Bloomfield ◽  
Ernest Harold Farmer
Keyword(s):  
Molecular Weight ◽  
Soluble Fraction ◽  
Insoluble Fraction ◽  
The Other ◽  
Major Fraction ◽  
Low Concentrations ◽  
Fractional Dissolution ◽  
Judicious Choice ◽  
Hydrocarbon Molecules ◽  
Soluble Fractions

Abstract Latex rubber which has been purified to the point at which it contains an insignificant amount of nitrogen can be separated by fractional dissolution in a mixture of petroleum and acetone into a series of hydrocarbon fractions of decreasing solubility and increasing molecular magnitude. All these fractions except the highest are soluble in petroleum and in benzene. Crepe rubber, on the other hand, appears invariably to contain a small, most-soluble fraction of oxygenated rubber, and a small similar quite insoluble fraction of material of high molecular weight. Between these extremes the rubber can be divided into fractions of increasing molecular weight, although, up to the present, about 70 per cent of the total rubber has appeared in a single fraction. It may be possible later, by judicious choice of another pair of solvents, to resolve this major fraction into a series of subfractions. Kemp and Peters refer to the effect of polar nonsolvents in reducing the viscosity of rubber solutions and also in assisting to bring gel rubber into solution, phenomena to which the polar molecules conceivably contribute by countering the forces of association between the rubber molecules. The present series of fractionations was conducted throughout in the presence of a polar nonsolvent (acetone), and hence may be considered to approach towards a separation of true rubber molecules as distinct from molecular aggregates. It is found, however, that, whereas the more soluble fractions of acetone-extracted crepe rubber contain small proportions of nitrogen, the least soluble fractions contain substantial proportions. Any effect which the nitrogenous material may have in assisting to link together hydrocarbon molecules to which it is attached, i. e., in contributing to the high-molecular condition of a portion of natural rubber, remains at present uncertain in character. The fractions of rubber, and especially the higher ones, show a strong tendency to become insoluble when they have once been freed from the last traces of solvent. It seems doubtful whether the decreased solubility is due to oxygen as it would require to be effective at exceedingly low concentrations.

scholarly journals Fractionation of lignosulphonates released during the early stages of delignification

1983 ◽  
Vol 61 (2) ◽  
pp. 416-420 ◽  
Author(s):  
Norman G. Lewis ◽  
David A. I. Goring ◽  
Alfred Wong
Keyword(s):  
Molecular Weight ◽  
High Performance ◽  
Black Spruce ◽  
Gel Permeation Chromatography ◽  
Bimodal Distribution ◽  
High Yield ◽  
Low Molecular Weight ◽  
Lower Yield ◽  
Spruce Wood ◽  
Gel Permeation

High-yield spent bisulphite liquor (HY-SBL) from sulphonated black spruce wood (Piceamariana) was fractionated by gel permeation chromatography (GPC) and by high-performance liquid chromatography (HPLC). The GPC fractionation gave a wide bimodal distribution, whereas with HPLC, a more detailed resolution was seen with the bulk of the fraction giving several clearly defined peaks. The paucidisperse material was further concentrated by a bulk fractionation of the crude SBL which included complexing the lignosulphonates with dicyclohexylamine. The isolated paucidisperse material was found to be dialyzable and to constitute 90% of the lignosulphonate in the sample of SBL. If the bisulphite pulp obtained was recooked in fresh acid sulphite liquor to a lower yield, most of the lignosulphonate dissolved was widely polydisperse with no indication of the discrete components resolvable by HPLC. However, 25% of the lignin made soluble was in the form of the paucidisperse fractions. In all, we were able to obtain about 50% of the lignin in spruce wood as a relatively low molecular weight lignosulphonate resolvable into discrete fractions by HPLC.

The Research of Silane Oligomer with Lower Valatilization Rate for Protecting Concrete

2013 ◽  
Vol 357-360 ◽  
pp. 1318-1322 ◽  
Author(s):  
Hong Yao Sun ◽  
Zheng Yang ◽  
Gao Xia Sun ◽  
Xue Feng Xu
Keyword(s):  
Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Chloride Ions ◽  
Polymerization Reaction ◽  
Low Molecular Weight ◽  
Construction Process ◽  
Reaction Conditions ◽  
Hydrophobic Agent ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

As one of the measures to improve the durability of concrete, silane penetrating hydrophobic agents can preserve the properties of respiratory function of concrete and can prevent the penetration from harmful medium such as chloride ions. Because of low molecular weight of the silane penetrating hydrophobic agent such as isobutyl triethoxysilane, high volatilization rate of silane can result in waste of material in construction process. The silane oligomer was obtained by radical polymerization reaction with suitable monomers, initiators and reaction conditions. Furthermore, we verified the structure of the silane oligomer by FT-IR spectroscopy and got its molecular weight by GPC(Gel Permeation Chromatography). The silane oligomer with lower volatilization rate has excellent properties of hydrophobicity, higher penetration depth and resistance to chloride ions penetration.

Sulphydryl Oxidation in the Mechanism of Molecular-Weight Conversion of Renin in Dog Kidney

1982 ◽  
Vol 62 (2) ◽  
pp. 157-162 ◽  
Author(s):  
Fumihiko Ikemoto ◽  
Kazuo Takaori ◽  
Hiroshi Iwao ◽  
Kenjiro Yamamoto
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Renal Cortex ◽  
Soluble Fraction ◽  
Low Molecular Weight ◽  
Oxidizing Agent ◽  
Nitrobenzoic Acid ◽  
Binding Substance ◽  
Sh Group ◽  
Dog Kidney

1. A high-molecular-weight renin (Mr 60 000) was formed by the reaction of a low-molecular-weight renin (Mr 40 000) with a renin-binding substance in canine renal cortical extract in the presence of the sulphydryl (SH) group oxidizing agent potassium tetrathionate; thus the reaction required SH oxidation. 2. Renin extracted from isolated renin granules was adsorbed on to thiopropyl Sepharose 6B, and then liberated with dithiothreitol (50 mmol/l), indicating that it possessed on SH moiety(s). 3. However, the renin was capable of reaction with the renin-binding substance even after its SH moiety (or moieties) was protected with 5,5′-dithiobis-(2-nitrobenzoic acid). 4. The high-molecular-weight renin was converted into the low-molecular-weight renin by incubation (37°C, 15 min) with cytosol (soluble fraction) of renal cortex and liver. Such converting ability was diminished after the cytosol was treated with perchloric acid or potassium tetrathionate. 5. These results suggest that the reaction of renin with the renin-binding substance does not require disulphide bond(s) and that an enzymelike substance which is sensitive to SH oxidation is involved in the conversion from the high-molecular-weight renin into the low-molecular weight renin.

MOLECULAR WEIGHT AND PHYSICAL PROPERTIES OF A LIPOPROTEIN FROM THE FLOATING FRACTION OF EGG YOLK

1958 ◽  
Vol 36 (1) ◽  
pp. 937-949 ◽  
Author(s):  
K. J. Turner ◽  
W. H. Cook
Keyword(s):  
Molecular Weight ◽  
Sodium Chloride ◽  
Lipid Content ◽  
Soluble Fraction ◽  
Egg Yolk ◽  
Low Molecular Weight ◽  
Molecular Weights ◽  
Ether Extraction ◽  
Soluble Material ◽  
Different Levels

Ether extraction removes 80% of the floating fraction of egg yolk from its solution in 2.5% sodium chloride. On removal of the ether and dialysis against specific solvents two thirds of the remaining lipoprotein (40% lipid) precipitates, leaving a soluble fraction containing 50% lipid. The soluble and insoluble portions probably represent different levels of degradation rather than different lipoproteins since both materials are apparently derived by ether extraction from a natural entity of much higher lipid content. The soluble fraction is heterogeneous and has mean molecular weights of M w = 5.4 × 105by light-scattering methods, and M n = 3.4 × 105by osmotic pressure. A "light" fraction obtained by centrifuging and representing 38% of the soluble material had M w = 3.4 to 3.5 × 105. Heterogeneity in lipid content appears to be responsible for the low molecular weight (M w = 2.4 × 105) obtained by sedimentation.

Study of the fractional composition of wheat proteins and macaroni products during storage

2021 ◽  
pp. 776-783
Author(s):  
I.A. Tarasova ◽  
K.B. Gurieva ◽  
E.A. Tarasova ◽  
S.L. Beletskiy ◽  
N.A. Khaba
Keyword(s):  
Molecular Weight ◽  
Fractional Composition ◽  
Gel Permeation Chromatography ◽  
Weight Fraction ◽  
Protein Fractions ◽  
Low Molecular Weight ◽  
English Version ◽  
Wheat Proteins ◽  
Photometric Detection ◽  
Main Protein

The results of the molecular weight distribution of wheat proteins and macaroni products are presented. The fractional composition of proteins was determined by gel permeation chromatography on a Knauer Smartline chromatograph; preliminary hydrolysis was carried out using a thermostable bacterium α-Amylase, then it was centrifuged, filtered through a Teflon filter, and the size of protein molecules was determined by photometric detection at a wavelength of 280 nm. It has been shown that the main protein fraction in both wheat and macaroni products is a low molecular weight fraction up to 3 kD (up to 79.4% of all protein fractions). The fraction with low and medium molecular weight from 3 to 10 kD accounted for 2.7 to 48.2%, while the fraction with a molecular weight of more than 10 kD accounted for up to 15.2%. During storage, a redistribution of protein fractions and their enlargement were noted. English version of the article is available at URL: https://panor.ru/articles/study-of-the-fractional-composition-of-wheat-proteins-and-pasta-products-during-storage/74321.html

Fractionation and characterization of lignin carbohydrate complexes (LCCs) of Eucalyptus globulus in residues left after MWL isolation. Part I: Analyses of hemicellulose-lignin fraction (HC-L)

Holzforschung ◽  
2012 ◽  
Vol 66 (4) ◽  
Author(s):  
Yasuyuki Miyagawa ◽  
Ooki Takemoto ◽  
Toshiyuki Takano ◽  
Hiroshi Kamitakahara ◽  
Fumiaki Nakatsubo
Keyword(s):  
Acetic Anhydride ◽  
Lithium Chloride ◽  
Eucalyptus Globulus ◽  
Soluble Fraction ◽  
Insoluble Fraction ◽  
Milled Wood Lignin ◽  
Cellulose Solvent ◽  
Lignin Fraction ◽  
Subsequent Deacetylation

Abstract The residual wood meal left after milled wood lignin (MWL) isolation (MWR) was extracted with the cellulose solvent lithium chloride/N,N-dimethylacetamide (LiCl/DMAc) to obtain a soluble fraction (C-L) and an insoluble fraction (C-L-residue). The C-L-residue was further extracted with the hemicellulose solvent 3 M NaOH to give a soluble fraction named hemicellulose-lignin fraction (HC-L) with 21.3% yield based on MWR. It was found that HC-L was composed of xylan, cellulose and lignin with abundant S-type β-O-4 substructures. HC-L lignin was bonded to HC-L cellulose or HC-L hemicelluloses or both. The method, which comprised acetylation for hardwood xylan (by acetic anhydride/pyridine/formamide) and extraction with chloroform, was found to be effective for selective xylan acetate fractionation. HC-L was further fractionated by the same method and subsequent deacetylation to give a xylan-lignin fraction (X-L) in 11.3% yield based on HC-L. X-L was composed mainly of xylan and lignin with abundant S-type β-O-4 substructures, and bonded to X-L xylan. X-L is considered as a promising fraction for elucidation of the structure of lignin-carbohydrate linkages.

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