Carbon-13 Nuclear Magnetic Resonance Spectrometry

Robert, D.

doi:10.1007/978-3-642-74065-7_18

Cited by 112 publications

(150 citation statements)

References 30 publications

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“…3, inset) indicates a possible broad peak. Concurrent with an increase in intensity assigned to H-type units are decreases in resonances assigned to S-and G-type units (for example, 152 ppm assigned to S 3 and S 5 (26)). The lower abundance of S-and G-type lignin units can also be determined by the decrease in the methoxyl peak at 56 ppm, although decreases in total lignin content can also contribute to the loss in signal intensity.…”

Section: Resultsmentioning

confidence: 99%

Increase in 4-Coumaryl Alcohol Units during Lignification in Alfalfa (Medicago sativa) Alters the Extractability and Molecular Weight of Lignin

Ziebell

Gracom

Katahira

et al. 2010

Journal of Biological Chemistry

114

108

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The lignin content of biomass can impact the ease and cost of biomass processing. Lignin reduction through breeding and genetic modification therefore has potential to reduce costs in biomass-processing industries (e.g. pulp and paper, forage, and lignocellulosic ethanol). We investigated compositional changes in two low-lignin alfalfa (Medicago sativa) lines with antisense down-regulation of p-coumarate 3-hydroxylase (C3H) or hydroxycinnamoyl-CoA:shikimate hydroxycinnamoyltransferase (HCT). We investigated whether the difference in reactivity during lignification of 4-coumaryl alcohol (H) monomers versus the naturally dominant sinapyl alcohol and coniferyl alcohol lignin monomers alters the lignin structure. Sequential base extraction readily reduced the H monomer content of the transgenic lines, leaving a residual lignin greatly enriched in H subunits; the extraction profile highlighted the difference between the control and transgenic lines. Gel permeation chromatography of isolated ball-milled lignin indicated significant changes in the weight average molecular weight distribution of the control versus transgenic lines (CTR1a, 6000; C3H4a, 5500; C3H9a, 4000; and HCT30a, 4000).The advent of large-scale liquid fuel production from biomass has served to highlight how difficult it is to commercially process biomass effectively and efficiently. Much of the difficulty is due to the recalcitrant nature of lignocelluloses (1), a complex interlinking structure composed of cellulose, hemicelluloses, and lignin that makes up the bulk of terrestrial biomass. Accessibility to the cell wall is influenced by lignin, which provides structural integrity to the cell wall. Both total lignin content and lignin monomer composition may impact the ease with which biomass is processed. This study examines whether lignin molecular weight is altered by changing the lignin monomer composition and if these changes affect the ease with which lignin can be removed by chemical processing.Three monomers (Fig. 1), 4-coumaryl alcohol (H), 2 coniferyl alcohol (G), and sinapyl alcohol (S), polymerize in what is thought to be a combinatorial fashion to form the bulk of the lignin polymer (2, 3). The amount of each unit depends on the species, age, cell type, and tissue type (4, 5). The presence of each additional methoxy group on a lignin unit results in one less reactive site (S Ͻ G Ͻ H) and therefore fewer possible combinations during the polymerization reaction. For example, the S unit has no vacant 5-position; therefore 5,5Ј-cross-linking is unavailable for lignin S subunits. As a result, lignin rich in S subunits is more easily depolymerized than lignin rich in G subunits.The relative level of S and G lignin subunits is expressed as the S/G ratio, an important measurement used in the assessment of biomass. H lignin subunits are present in low levels in natural materials (4.9% of lignin in wild-type alfalfa (1) and 0.8% in Norway Spruce (6)); consequently, less is known about lignin high in H subunits and its impact on biomass processing. I...

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Section: Resultsmentioning

confidence: 99%

Increase in 4-Coumaryl Alcohol Units during Lignification in Alfalfa (Medicago sativa) Alters the Extractability and Molecular Weight of Lignin

Ziebell

Gracom

Katahira

et al. 2010

Journal of Biological Chemistry

114

108

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“…The integral of aromatic region (102-160 ppm) was calibrated to six, which represents six aromatic carbons (Landucci et al 1998;Ralph and Landucci 2010;Min et al 2013;Wells et al 2013). Quantitative evaluation of functional groups (OH phen and OMe) and carbohydrates was thus integrated related to this value (Robert 1992;Faix et al 1994;Ralph and Landucci 2010;Choi and Faix 2011;Min et al 2013).…”

Section: Quantitative Nmr Spectroscopymentioning

confidence: 99%

The molecular properties and carbohydrate content of lignins precipitated from black liquor

Zhu

Westman²,

Theliander³

2014

Holzforschung

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Precipitation and utilization of lignin from black liquor (BL) offers many promising advantages to modern kraft pulp mills. A novel process, known as "LignoBoost", has recently been introduced as a process for separating lignin from BL; it results in lignins with a low ash and high dry solid content. There is a lack of knowledge regarding the influences of process parameters on the behavior of lignin in the precipitation step. In this study, the yield of precipitated lignin and its average molecular weight (MWt) and carbohydrate content were the focus. Nuclear magnetic resonance (NMR) analysis showed that the lignin yield increased at lower pH and temperatures or when the ion strength of BL was elevated. High yield lignins contained more low MWt components and such lignins have more phenolic OH and methoxy groups. Xylan content of the lignins decreased with decreasing pH and increasing temperature, but glucomannan content was virtually unaffected by the conditions of precipitation.

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“…The spectra for 13 C were acquired at 50 °C using an inverse gated decoupling pulse sequence. Several scans for each sample were collected with a pulse delay of 12 s (Robert 1992).…”

Section: Characterization Of Ethanol Organosolv Lignin (Eol)mentioning

confidence: 99%

Ethanol Organosolv Pretreatment of Typha Capensis for Bioethanol Production and Co-Products

Audu

Brosse²,

Desharnais³

et al. 2012

BioResources

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Typha capensis (TC), a highly prolific, invasive grass found in many parts of the world, is a common pest that grows in waterways, but it may be a good lignocellulosic substrate for bioethanol production. Sulfuric acid-catalyzed ethanol organosolv pretreatment was used to investigate the possibility of harnessing the benefits of both fermentable sugars and lignin by reacting at varying defined severity levels. It was observed that TC polysaccharides were particularly susceptible to hydrolysis, which was associated with the formation of a large amount of pseudo-lignin due to the degradation of sugars. Pseudo-lignin had a negative impact on enzymatic hydrolysis. At optimal conditions, the process enabled the fractionation of TC into glucan-rich solid fractions with enhanced digestibility, recovery of organosolv lignin, and easily hydrolysable hemicellulose sugars in the liquid stream of pretreatment analytes. About 68.33% of the glucan in the raw TC was recovered, and 85.23% fermentable sugars from water-soluble and enzyme-hydrolyzed pulp were attained. Up to 67% of the initial lignin in TC was extracted as ethanol organosolv lignin (EOL).

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Carbon-13 Nuclear Magnetic Resonance Spectrometry

Cited by 112 publications

References 30 publications

Increase in 4-Coumaryl Alcohol Units during Lignification in Alfalfa (Medicago sativa) Alters the Extractability and Molecular Weight of Lignin

Increase in 4-Coumaryl Alcohol Units during Lignification in Alfalfa (Medicago sativa) Alters the Extractability and Molecular Weight of Lignin

The molecular properties and carbohydrate content of lignins precipitated from black liquor

Ethanol Organosolv Pretreatment of Typha Capensis for Bioethanol Production and Co-Products

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