T. Kishimoto, A. Ueki, H. Takamori, Y. Uraki, M. Ubukata
Delignification mechanism during high-boiling solvent pulping. Part 6: Changes in lignin structure analyzed by 1H-13C correlation 2-D NMR spectroscopy
In order to investigate the delignification mechanism during
high-boiling solvent (HBS) pulping, softwood HBS lignin
samples from todo fir (Abies sachalinensis) were
analyzed by 1H–13C correlation NMR spectroscopy
(HMQC). Nine lignin model compounds that may represent
the substructures in HBS lignin were prepared. The
1H and 13C NMR spectral data were compared with HBS
lignin samples. The HMQC spectra of HBS lignin samples
showed the disappearance of ?-O-4 structures.
Introduction of a pulping solvent into lignin was plainly
observed with new signals in aliphatic regions. Only the
erythro ?-1 structure was detected in softwood milled
wood lignin from todo fir by HMQC spectra. The ?-1
structure was very reactive and probably produced the
stilbene structure. The ?-? and ?-5 structures remained
in HBS lignin. The 4-O-5 structure was successfully
detected by HMQC spectra, and it was found to be stable
under the conditions used.
Holzforschung, Walter de Gruyter
Print ISSN: 0018-3830
Volume: 58, 07/2004
Pages: 355 - 362
Show full article (external site)
Show all available items of this journal
Search
