NMR Studies of Lignins. 3. 1H NMR Spectroscopic Data for Lignin Model Compounds.

Lundquist, Knut; Mannervik, Bengt; Nordfors, Kerstin; Nishida, Toshiaki; Enzell, Curt R.; Reid, William W.; Yanaihara, Noboru; Yanaihara, Chizuko

doi:10.3891/acta.chem.scand.33b-0418

Cited by 40 publications

(21 citation statements)

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“…In 1 H NMR spectra of acetylated lignins in chloroform-d 1 , signals assigned to aromatic protons appear at about d 6.90 for gymnosperm lignin (guaiacyl protons), and at d 6.90 and 6.65 (syringyl protons) for angiosperm lignin [33]. The acetylated Björkman lignins of the core and wood fractions exhibited two strong signals at the aromatic region, d 6.65 and 6.90, in the 1 H NMR spectra (Fig.…”

Section: Spectrometric Characteristics Of Bast Fiber and Bark Ligninmentioning

confidence: 91%

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

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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

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Section: Spectrometric Characteristics Of Bast Fiber and Bark Ligninmentioning

confidence: 91%

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

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“…The 2D-D 13 C/ 1 H spectra obtained here reaffirm the reliability of the assignments of well-known major structural units of lignin in 13 C-1 H correlation (HSQC) spectra: b-aryl ether (b-O-4, structure A), phenylcoumaran (b-5, B), resinol (b-b, C), and dibenzodioxocin (5-5/4-O-b, D) structural units which have been assigned in detailed studies since the 1970s, based on the NMR chemical shifts of numerous lignin model compounds (Lundquist 1979;Hauteville et al 1986;Karhunen et al 1995;Li et al 1997;Ralph et al 2004b). Different NMR techniques, such as HSQC-DEPT (which helps distinguish CH, CH 2 , and CH 3 carbons in the HSQC format), long-range 13 C-1 H correlation (HMBC, which correlates protons and carbons within 3-bonds of each other), and particularly useful experiments, such as HSQC-TOCSY (in which a sidechain carbon correlates with all protons in that structure's side-chain), have also been applied to lignin studies.…”

Section: Differential Nmr Spectroscopy Of 13 C-dhps and Of Ginkgo Mwlmentioning

confidence: 99%

2D-NMR (HSQC) difference spectra between specifically ¹³C-enriched and unenriched protolignin of Ginkgo biloba obtained in the solution state of whole cell wall material

Terashima¹,

Akiyama

Ralph

et al. 2009

HFSG

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In the structural analysis of lignins by 13 C-NMR, signal overlap limits definitive assignment and accurate intensity measurement. Selective labeling by 13 C-enrichment of a specific carbon in lignin enhances its signal intensity in the spectrum. Further enhancement of the specifically labeled carbons can be realized via difference spectra created from the enriched and unenriched samples. Difference 2D 13 C-1 H correlation (HSQC) NMR spectra, derived from the spectra of specifically 13 C-enriched lignin model polymers (so-called dehydrogenation polymers) and their unenriched counterparts, take advantage of the enhanced dispersion afforded by both 13 C and 1 H chemical shifts, diminishing the difficulties arising from the signal-overlap problem and aiding in definitive signal assignments. In this research, protolignin in xylem cell walls was specifically 13 C-enriched at all of the individual phenylpropanoid side-chain carbons by feeding 13 Cenriched coniferins to growing stems of Ginkgo biloba. The whole xylem fractions containing 13 C-enriched and unenriched protolignins were dissolved in a mixture of N-methylimidazole and DMSO, and then acetylated. Solution state 2D-NMR (HSQC) spectra of the acetylated whole cell wall were acquired. Difference spectra between the walls containing 13 C-enriched and unenriched lignins afforded simplified 2D spectra in which well-separated signals were assigned exclusively to the specifically enriched carbons. This novel NMR technique provides a useful tool for elucidation of entire protolignin in the cell wall of ginkgo xylem.

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“…Elucidation of the DHP and lignin structures requires the synthesis and characterization of adequate low molecular mass model compounds and strongly relies on the application of NMR spectroscopic techniques (Lüdemann and c Nimz 1974a, b;Nimz et al 1974;Nimz and Lüde-mann 1976;Gagnaire and Robert 1977;Lundquist 1979;Brunow and Lundquist 198b;Nimz et al 1981Nimz et al , 1984Ralph et al 1992a, b,'.^993). In the past, the oxidative coupling of p-propenyl phenol derivatives using one-electron oxidants such äs ferne Chloride, potassium ferricyanide, or peroxidases-H 2 O 2 , provided access to dimeric lignin model compounds (Leopold 1950;Sarkanen and Wallis.…”

Section: Introductionmentioning

confidence: 98%

A Biomimetic Route to Lignin Model Compounds via Silver (I) Oxide Oxidation. 1. Synthesis of Dilignols and Non-cyclic Benzyl Aryl Ethers

Quideau¹,

Ralph²

1994

HFSG

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NMR Studies of Lignins. 3. 1H NMR Spectroscopic Data for Lignin Model Compounds.

Cited by 40 publications

References 0 publications

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

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

2D-NMR (HSQC) difference spectra between specifically ¹³C-enriched and unenriched protolignin of Ginkgo biloba obtained in the solution state of whole cell wall material

A Biomimetic Route to Lignin Model Compounds via Silver (I) Oxide Oxidation. 1. Synthesis of Dilignols and Non-cyclic Benzyl Aryl Ethers

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NMR Studies of Lignins. 3. 1H NMR Spectroscopic Data for Lignin Model Compounds.

Cited by 40 publications

References 0 publications

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

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

2D-NMR (HSQC) difference spectra between specifically 13C-enriched and unenriched protolignin of Ginkgo biloba obtained in the solution state of whole cell wall material

A Biomimetic Route to Lignin Model Compounds via Silver (I) Oxide Oxidation. 1. Synthesis of Dilignols and Non-cyclic Benzyl Aryl Ethers

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2D-NMR (HSQC) difference spectra between specifically ¹³C-enriched and unenriched protolignin of Ginkgo biloba obtained in the solution state of whole cell wall material