Applicability of the 13C NMR “inadequate” experiment to lignin, a natural polymer.

Guittet, Éric; Lallemand, J. Y.; Lapierre, C.; Monties, Bernard

doi:10.1016/s0040-4039(00)98132-2

Cited by 21 publications

(5 citation statements)

References 8 publications

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“…Sophisticated sequences have been applied to lignin model compounds (Ralph 1988), revealing the long-range C-H correlations critical in proving structure. The 2-D INADEQUATE (Incredible Natural Abundance Double Quantum Transfer Experiment) sequence successfully mapped the carbon skeleton of a "C-enriched aspen MWL sample through observation of directly bonded C-C atoms (Guittet et al 1985). This sequence also provides stereochemical information about lignin structure.…”

Section: Qualitative Analysismentioning

confidence: 99%

Carbon-13 Nuclear Magnetic Resonance Spectrometry

Robert¹

1992

Methods in Lignin Chemistry

108

136

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Section: Qualitative Analysismentioning

confidence: 99%

Carbon-13 Nuclear Magnetic Resonance Spectrometry

Robert¹

1992

Methods in Lignin Chemistry

108

136

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“…The HMQC experiment has enabled structural investigations of lignin at natural abundance of 13 C (Ede and Brunow, 1992;Fukagawa et al, 1991). The 13 C-13 C correlated experiment, 2D INADEQUATE, has been applied to 13 C-enriched MWL (Guittet et al, 1985;Bardet et al, 1986), allowing the assignment of 13 C chemical shifts of predominant C-C bonds of lignin.…”

Section: Introductionmentioning

confidence: 99%

“…Most of the spin systems in lignins have been assigned reliably by applying 1 H-detected 1 H-13 C correlation (HMQC) and homonuclear Hartman-Hahn (HO-HAHA) in concert (Ede and Brunow, 1992 al., 1985;Kilpela ¨inen et al, 1994a;Kilpela ¨inen, 1994).…”

Section: Introductionmentioning

confidence: 99%

Identification of Side-Chain Structures in a Poplar Lignin Using Three-Dimensional HMQC−HOHAHA NMR Spectroscopy

Ämmälahti

Brunow

Bardet

et al. 1998

J. Agric. Food Chem.

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The structure of an acetylated 13C-enriched poplar wood lignin preparation was studied using three-dimensional HMQC−HOHAHA NMR spectroscopy. This method takes advantage of the large dispersion of 13C chemical shifts to resolve individual 1H chemical shifts. The whole spin system of a 1H−13C correlation observed in an HMQC spectrum, even for minor components and unknown structural units, can be traced out. It is shown here that both trans- and cis-isomers of 6,7-dihydrodibenzo(e,g)(1,4)-dioxocin, a recently discovered prominent linkage in softwood lignins, occur also in hardwood lignin. Moreover, the poplar lignin preparation contains small amounts of noncyclic α-aryl ether linkages. Signals from a side chain of unknown structure are tentatively assigned to a spiro-cyclohexadienone. Keywords: NMR; 3D HMQC−HOHAHA; lignin

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“…The correlation peaks symmetrically placed about the diagonal correspond to directly bonded carbon atoms (8,16). The 2D INADEQUATE experiments were conducted at 100.13 MHz with a Bruker AM 400 spectrometer.…”

Section: D-inadequate Experimentmentioning

confidence: 99%

“…A selection of these 16 fi-O-4' dimers has been synthesized and their stereochemistry confirmed by x-ray crystallography (77). The 2D INADEQUATE 13 C spectrum of the 13 C enriched MWL sample revealed most of the 13 C-13 C bonds found in the main dimeric lignin structures and thus provides a direct reflection of the lignin carbon skeleton (8,16). In addition the CP-Coc carbon correlations assigned to the β-0-4' dimers represent a set of four cross peaks (75), clearly discerned from four maxima in the density contours ( Figure 2), which are centered at 83.5 -72.2 ppm (I), 84.5-71.4 ppm (II), 86.0-72.5 ppm (III) and 87.2-71.9 ppm (IV).…”

Section: D-inadequate Experimentmentioning

confidence: 99%

Improvement in NMR Structural Studies of Lignin Through Two- and Three-Dimensional NMR Detection and Isotopic Enrichment

Robert¹,

Ämmälahti²,

Bardet³

et al. 1998

ACS Symposium Series

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2D and 3D NMR spectra of uniformly 13 C enriched lignin and specifically labeled ( 13 C and 199 Hg) lignin improve substantially the prospects for lignin structural analysis. The 2D INADEQUATE 13 C NMR spectrum of 13 C enriched aspen milled wood lignin allows observation, within the polymeric lignin structure, of chemically distinct β-0-4' diastereoisomers. In this same sample, using 2D -HMQC, 2D-HOHAHA and 3D-HMQC/HOHAHA pulse sequences, one can observe minor but important structures such as β-1', α-O-4' and eight membered ring dibenzodioxocin units, through 1 H-1 H, 1 H-13 C, and 1 H-13 C-13 C-1 H correlations. It was shown that selective 13 C labeling of the propyl side chain of hardwood and softwood lignin, through exogenous administration of labeled coniferin, does not appear to perturb lignin biosynthesis and therefore provides a convenient means for putting an NMR probe into effect. Mercuration of lignin provides selective labeling of the aromatic ring which can be correlated with the lignin condensation pattern. 1 H-199 Hg HMQC NMR experiments allow assignments to be made of the mercurated sites in model compounds.Classical one-dimensional 13 C NMR spectroscopy is a very efficient tool for lignin structural analysis. Nevertheless it suffers from disadvantages such as important signal overlaps in many spectra, as well as indirect signal assignments, which rely on comparison with model compounds. In attempts to circumvent these problems, we employed various 2D and 3D NMR pulse sequences on 13 C enriched or selectively 13 C and 199 Hg labeled lignin samples. The multidimensional NMR techniques increase by polarization transfer the sensitivity of nuclei with low sensitivity, and the large range of the carbon chemical shifts in lignin makes 'H-^C and 13 C-13 C correlation methods efficient for structural analysis. 13 C enrichment provides signal enhancement which allow detection of very minor signals and make possible the use

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Applicability of the 13C NMR “inadequate” experiment to lignin, a natural polymer.

Cited by 21 publications

References 8 publications

Carbon-13 Nuclear Magnetic Resonance Spectrometry

Carbon-13 Nuclear Magnetic Resonance Spectrometry

Identification of Side-Chain Structures in a Poplar Lignin Using Three-Dimensional HMQC−HOHAHA NMR Spectroscopy

Improvement in NMR Structural Studies of Lignin Through Two- and Three-Dimensional NMR Detection and Isotopic Enrichment

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