A new and facile method for isolation of lignin from wood based on complete wood dissolution

Holzforschung ◽  
2008 ◽  
Vol 62 (1) ◽  
pp. 15-23 ◽  
Author(s):  
Mario Fasching ◽  
Philipp Schröder ◽  
R. Petra Wollboldt ◽  
Hedda K. Weber ◽  
Herbert Sixta
Keyword(s):  
Beech Wood ◽  
High Yield ◽  
Resonance Spectroscopy ◽  
Hydroxyl Groups ◽  
Milled Wood Lignin ◽  
Lignin Fraction ◽  
Extraction Step ◽  
Elemental Analyses ◽  
Phenolic Hydroxyl Groups ◽  
Total Dissolution

Abstract A new method for the isolation of lignin in high yield from wood and pretreated wood is presented, avoiding the liquid-solid extraction step of the classical milled wood lignin (MWL) isolation. Dissolved wood lignin (DWL) was obtained by total dissolution of ball milled wood in dimethylsulfoxide and N-methylimidazole (DMSO/NMI) followed by precipitation in dioxane/water in the course of which lignin and carbohydrate fractions were separated. The lignin fraction was purified. High lignin yields and the low number of separation steps belong to the advantages of the described method. DWL lignin was isolated from beech wood (Fagus sylvatica L.) and the sample was compared to MWL obtained by the classical Björkman method. Elemental analyses, methoxyl group content, potassium permanganate oxidation, infrared spectroscopy, and 1D and 2D nuclear magnetic resonance spectroscopy indicated that both lignin preparations are quite similar. However, MWL contained significantly more phenolic hydroxyl groups than DWL. The results indicated that MWL contains higher amounts of smaller fractions with broken β-O-4 linkages than DWL.

Removal of Phenolic Hydroxyl Groups in Lignin Model Compounds and Its Effect on Photostability

Holzforschung ◽  
2000 ◽  
Vol 54 (2) ◽  
pp. 127-132 ◽  
Author(s):  
Thomas Q. Hu ◽  
Graham R. Cairns ◽  
Brian R. James
Keyword(s):  
Hydrogen Transfer ◽  
Phenolic Hydroxyl ◽  
Hydroxyl Groups ◽  
Model Compounds ◽  
Lignin Model Compounds ◽  
Whatman Filter Paper ◽  
Elemental Analyses ◽  
Catalytic Hydrogen ◽  
Lignin Model ◽  
Phenolic Hydroxyl Groups

Summary The phenolic hydroxyl groups in the lignin model compounds, 2-methoxy-4-propylphenol and 4-hydroxy-3-methoxyacetophenone, were removed by first converting the hydroxyl groups to the trifluoromethanesulfonates (triflates) and then cleaving the triflate substituents via catalytic hydrogen transfer. The products, 1-methoxy-3-propylbenzene and 3-methoxyacetophenone, were characterized by 1H and 13C NMR, mass spectrometry and elemental analyses. The effect of the removal of the phenolic groups on the photostability of the model compounds was evaluated by impregnating the compounds into Whatman filter paper sheets, and subjecting them to an accelerated yellowing experiment in a UV chamber. The removal of the phenolic groups resulted in a significant yellowing inhibition, with a higher photostabilizing effect than methylation or acetylation of the hydroxyl, particularly for the model compound without an α-carbonyl group.

On the formation of diphenylmethane structures in lignin under kraft, EMCC®, and soda pulping conditions

1998 ◽  
Vol 76 (5) ◽  
pp. 506-512 ◽  
Author(s):  
Behzad C Ahvazi ◽  
Gerry Pageau ◽  
Dimitris S Argyropoulos
Keyword(s):  
Picea Mariana ◽  
Nmr Spectra ◽  
Kraft Pulp ◽  
Model Compound ◽  
Kraft Pulping ◽  
Hydroxyl Groups ◽  
Milled Wood Lignin ◽  
Kraft Process ◽  
Soda Pulping ◽  
Phenolic Hydroxyl Groups

This paper describes our efforts focused at defining the formation of diphenylmethane moieties in lignin during conventional kraft and soda pulping conditions. This objective was realized by confirming, initially, the assignment of a 31P NMR signal as being due exclusively to the presence of phosphitylated diphenylmethane (DPM) phenolic hydroxyl groups. More specifically, softwood milled wood lignin (Picea mariana) was subjected to kraft pulping conditions in the presence and absence of varying amounts of formaldehyde. After quantitative recovery of the lignin, the 31P NMR spectra were recorded and the spectra revealed selective signal growth in the region confined between 142.8 and 144.3 ppm, in accordance with previous model compound work and detailed calculations based on the Hammett principles. To further substantiate our conclusions we also carried out two series of isothermal (120°C) kraft and soda pulping experiments followed by quantitative determinations of the DPM moieties, and correlated our findings with the differences in chemistry known to occur between the two processes. Finally, diphenylmethane phenolic moieties were determined in isolated residual lignins from two western hemlock kraft pulp samples produced via an EMCC® mill protocol and a laboratory batch digester, respectively. These structures prevailed amongst the condensed phenolic units of the conventional pulp, providing additional evidence to support the fact that modern modified pulping technologies beneficially alter the structure of residual kraft lignin.Key words: phenyl groups, kraft pulping, modified kraft process, nuclear magnetic resonance (NMR), phosphorus spectroscopy.

Synthesis of Highly Functionalized Quinazoline-2,4(1H,3H)-diones from Isocyanides, Aniline and Isocyanate via Cu-Catalyzed Intermolecular C-H Activation Reactions

2020 ◽  
Vol 17 (11) ◽  
pp. 832-836
Author(s):  
Manijeh Nematpour ◽  
Hossein Fasihi Dastjerdi ◽  
Mehdi Jahani ◽  
Sayyed Abbas Tabatabai
Keyword(s):  
13C Nmr ◽  
Reaction Times ◽  
High Yield ◽  
One Pot ◽  
1H And 13C Nmr ◽  
Activation Reaction ◽  
Elemental Analyses

A simple and appropriate procedure for the synthesis of quinazoline-2,4(1H,3H)-dione derivatives from isocyanides, aniline and isocyanate via the Cu-catalyzed intramolecular C-H activation reaction is reported. The advantages of this method are one-pot conditions, accessible starting materials- catalyst, high yield of products, and short reaction times. The structures are confirmed spectroscopically (1H- and 13C-NMR, IR and EI-MS) and by elemental analyses.

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

Molecules ◽  
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.

scholarly journals Synthesis of Poly(methyl methacrylate)-b-poly(N-isopropylacrylamide) Block Copolymer by Redox Polymerization and Atom Transfer Radical Polymerization

2018 ◽  
Vol 18 (3) ◽  
pp. 537 ◽  
Author(s):  
Melahat Göktaş ◽  
Guodong Deng
Keyword(s):  
Block Copolymers ◽  
Methyl Methacrylate ◽  
Atom Transfer Radical Polymerization ◽  
Radical Polymerization ◽  
Gel Permeation Chromatography ◽  
High Yield ◽  
Resonance Spectroscopy ◽  
Atom Transfer ◽  
Poly Methyl Methacrylate ◽  
Redox Polymerization

Poly(methyl methacrylate)-b-poly(N-isopropylacrylamide) [PMMA-b-PNIPAM] block copolymers were obtained by a combination of redox polymerization and atom transfer radical polymerization (ATRP) methods in two steps. For this purpose, PMMA macroinitator (ATRP-macroinitiator) was synthesized by redox polymerization of methyl methacrylate and 3-bromo-1-propanol using Ce(NH4)2(NO3)6 as a catalyst. The synthesis of PMMA-b-PNIPAM block copolymers was carried out by means of ATRP of ATRP-macroinitiator and NIPAM at 60 °C. The block copolymers were obtained in high yield and high molecular weight. The characterization of products was accomplished by using multi instruments and methods such as nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, gel permeation chromatography, and thermogravimetric analysis.

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