A Classification System of lignin spectra is presented, based on FT-IR Spectroscopy of more than hundred MWL's.The spectra were baseline corrected and normalized.Three main categories can be differentiated:(1) G type, (2) GS type, and (3) HGS type.The spectra within the GS category constitute a continuum, but they can be further subdivided into four groups. The Classification criteria are presented äs a table and illustrated by authentic FT-IR spectra obtained from MWL's. Peak-peaker lists of typical representatives of the three principal groups show the band intensities of normalizcd IR spectra. A triangulär coordinate System displays the correlation between the spectral features on the one hand, and the possible Normalization of FT-IR spectra composition of a lignin from its H , G, and S units on the other.

No abstract

Results of a comprehensive study on the chemical structure of lignin from plantation Eucalyptus globulus Labill are presented. Lignin has been isolated by a modified mild acidolysis method and thoroughly characterized by functional group analysis, by a series of degradation techniques (nitrobenzene oxidation, permanganate oxidation, thioacidolysis, and Py-GC-MS), and (1)H and (13)C NMR spectroscopy. Plantation Eucalyptus globulus lignin was found to be of the S/G type with an extremely high proportion of syringyl (S) units (82-86%) and a minor proportion of p-hydrophenyl propane (H) units (roughly 2-3 mol %). Unknown C-6 substituted and 4-O-5' type syringyl substructures represent about 65% of lignin "condensed" structures. Eucalypt lignin showed high abundance of beta-O-4 (0.56/C(6)) structures and units linked by alpha-O-4 bonds (0.23/C(6)). The proportion of phenylcoumaran structures was relatively low (0.03/C(6)). Different kinds of beta-beta substructures (pino-/syringaresinol and isotaxiresinol types) in a total amount of 0.13/C(6) were detected. ESI-MS analysis revealed a wide molecular weight distribution of lignin with the center of gravity of mass distribution around 2500 u.

No abstract

No abstract

No abstract

No abstract

No abstract