NMR Studies of Lignins. 4. Investigation of Spruce Lignin by 1H NMR Spectroscopy.

Lundquist, Knut; Aasen, Arne J.; Daasvatn, Kari; Forsgren, Björn; Gustafsson, Jan‐Åke; Högberg, B.; Becher, Jan

doi:10.3891/acta.chem.scand.34b-0021

Cited by 94 publications

(74 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Distribution of the diastereomeric forms in lignins has been studied by NMR spectral methods. The results are in agreement to the extent that approximately equal amounts of the diastereomeric forms are found in softwood lignins and there is a predominance of the erythro form in hardwood lignins (Lundquist 1980;Nimz et al 1984;Hauteville et al 1986;Saake et al 1996). Studies of the stereochemistry based on the formation of threonic acid and erythronic acid on ozonation Taneda et al 1989;Sarkanen et al 1992) are largely in accordance with the NMR spectroscopic results.…”

Section: Survey Of Different Types Of Lignin Unitsupporting

confidence: 76%

“…This is not surprising, because it is very difficult to obtain reliable quantitative lignin data. An example of the types of difficulty encountered in quantitative lignin analysis occurs in calculation of the abundance of condensed units in lignins on the basis of 1 H NMR spectroscopy (Ludwig et al 1964;Lundquist 1980). Calculation of condensed units is based on integration of the signal from aromatic protons (corrected for the contribution of some vinyl protons) together with determination of the number of phenylpropane units and consideration of the distribution of units 1-3 in the sample.…”

Section: The Bonding Of the Phenylpropane Unitsmentioning

confidence: 99%

See 1 more Smart Citation

Lignin Chemistry and its Role in Biomass Conversion

Brunow¹

2005

Biorefineries‐Industrial Processes and Products

View full text Add to dashboard Cite

Section: Survey Of Different Types Of Lignin Unitsupporting

confidence: 76%

Section: The Bonding Of the Phenylpropane Unitsmentioning

confidence: 99%

Lignin Chemistry and its Role in Biomass Conversion

Brunow¹

2005

Biorefineries‐Industrial Processes and Products

View full text Add to dashboard Cite

“…Results from 1 H NMR spectroscopy were also in agreement with low total yields of alkaline nitrobenzene oxidation and ozonation products. The signals at d 6.01 and 6.06 of 1 H NMR spectrum are assigned to the H a in erythro form and threo form of arylglycerol-b-aryl ether intermonomer linkages, respectively [34]. Spectra of acetylated Björkman lignins of three species of core and wood fractions and kenaf bast fiber exhibited stronger signals at d 6.01 than those at d 6.06, suggesting that the erythro form was the predominant form of arylglycerol-b-aryl ether intermonomer linkages.…”

Section: Spectrometric Characteristics Of Bast Fiber and Bark Ligninmentioning

confidence: 99%

Lignin characteristics of bast fiber and core in kenaf, bark and wood of paper mulberry and mulberry

Jin

Shao

et al. 2011

J Wood Sci

View full text Add to dashboard Cite

The structural features of bast fiber and core lignins in kenaf (Hibiscus cannabinus), bark and wood lignin of paper mulberry (Broussonetia papyrifera (L.) Vent 9 Broussonetia kazinoki Sieb.) and mulberry (Morus bombycis) were characterized by alkaline nitrobenzene oxidation, ozonation and methoxyl group determination. Björkman lignins were isolated from bast fiber and core, and bark and wood fractions of the plant samples, and structural characteristics were investigated by 1 H NMR and 13 C NMR spectroscopies. Kenaf bast fiber gave very high molar ratio of syringaldehyde to vanillin (S/V) of alkaline nitrobenzene oxidation products, while methoxyl content was about the same as that of the core fraction. Results of 1 H NMR and 13 C NMR of Björkman lignin suggested the presence of aliphatic fragments in lignins isolated from paper mulberry and mulberry bark, but not in kenaf bast fiber. The lower yield of alkaline nitrobenzene oxidation products from bast fiber and bark might be due to the higher content of condensed structure of lignin compared to core fraction. Total yield of erythronic (E) and threonic (T) acids of ozonation products and the molar ratio of erythronic acid to threonic acid (E/T) of the bast fibers and bark were lower than the corresponding core and wood fractions, suggesting that the contents of arylglycerol-baryl ether intermonomer linkages in the bast fiber and bark lignin were lower than those of the core and wood fractions. Methoxyl content of bark lignin was lower than the corresponding wood lignin. The methoxyl content of the extract-free kenaf bast fiber was similar to that of the core fraction, while the values of paper mulberry and mulberry bark were about one-half of the corresponding wood fractions, respectively. In bark lignins, the methoxyl contents of Klason lignin and Björkman lignin from bark were lower than those of the extract-free barks. This result suggests that the purity of Klason lignin and Björkman lignins of bark may be rather low.Keywords Kenaf bast fiber and core Á Mulberry bark and wood Á E/T ratio Á S/V ratio Á Methoxyl group

show abstract

“…Stereochemical studies on lignins have shown that the arylglycerol-fl-aryl ether structure (1) which is the predominant structural element in lignins (Sarkanen, Ludwig 1971;Adler 1977), exists in nearly equal amounts of erythro and threo isomers in spruce lignin (Lundquist 1980;Nimz et al 1984;Hauteville et al 1986;Matsumoto et al 1986; see also Ede et al 1990). In hardwood lignins, on the other hand, there is a predominance of erythro forms of such structures (Hauteville et al 1986).…”

Section: Introductionmentioning

confidence: 99%

On the distribution of the diastereomers of the structural elements in lignins: the steric course of reactions mimicking lignin biosynthesis

Brunow¹,

Karlsson²,

Lundquist³

et al. 1993

Wood Sci.Technol.

View full text Add to dashboard Cite

Stereochemical studies on the formation of the diastereomers of arylglycerol-fl-aryl ether structures during lignin biosynthesis have been carried out with model compounds. The addition of water to quinone methides of the fl-syringyl ether type gives arylglycerol fl-syringyl ethers with a predominance of the erythro isomer when the pH of the medium is low. Since erythro forms of arylglycerol fl-syringyl ethers are prevalent in hardwood lignins, this indicates that the pH of the medium in which lignin biosynthesis occurs is lower than has been assumed until now. Equilibration studies with non-phenolic model compounds of the arylglycerol-fl-guaiacyl ether and fl-syringyl ether types under acidolysis conditions indicate that the erythro predominance observed in the syringyl ethers in lignins does not correspond to equilibrium conditions. A remarkable resistance to acidolysis is observed in the model compounds of etherified syringylglycerol fl-syringyl ether type.

show abstract

NMR Studies of Lignins. 4. Investigation of Spruce Lignin by 1H NMR Spectroscopy.

Cited by 94 publications

References 0 publications

Lignin Chemistry and its Role in Biomass Conversion

Lignin Chemistry and its Role in Biomass Conversion

Lignin characteristics of bast fiber and core in kenaf, bark and wood of paper mulberry and mulberry

On the distribution of the diastereomers of the structural elements in lignins: the steric course of reactions mimicking lignin biosynthesis

Contact Info

Product

Resources

About