Characterization of Lignins from Organosolv Pulping According to the Organocell Process. Part 3. Permanganate Oxidation and Thioacidolysis

Milled wood lignin (MWL) was isolated from Quebracho colorado wood which was extracted cither with NaOH or with ethanol-water. Spectroscopic and analytical investigations show that tannins are still present in MWL from ethanol-water extracted wood. In chemical composition it corresponds to other hardwood lignin dcspite the relatively wide Variation betwcen different species. Alkali treatment of the wood causes certain changes in the chemical structure of MWL.Ultimate analyses were carried out with an automatic CHN-analyzcr (Hcraeus).The oxygen percentage was obtained by substraction.The methoxyl content was evaluated according toVieböck and Schwappach (1930) in a modified device (Fengel, Przyklcnk 1970).

Section: Discussionmentioning

confidence: 97%

Chemical Studies on the Wood of Quebracho colorado.(Schinopsis balansaeEngl.). Part 2. Investigations of the Lignin

Fengel¹

1991

“…Permanganate oxidation is one of the methods used to determine the distribution of uncondensed and condensed units in residual lignins (Gellerstedt and Lindfors 1984;Gellerstedt 1992;Lindner and Wegener 1990;Hortling et al 1992). Permanganate oxidation is one of the methods used to determine the distribution of uncondensed and condensed units in residual lignins (Gellerstedt and Lindfors 1984;Gellerstedt 1992;Lindner and Wegener 1990;Hortling et al 1992).…”

Section: Introductionmentioning

confidence: 99%

Lignin Analysis by Permanganate Oxidation. II. Lignins in Acidic Organosolv Pulps

Bose¹,

Wilson²,

Hausch³

et al. 1999

The permanganate oxidation method was used to analyze residual lignins in Norway spruce (Picea abies) organosolv pulps. The pulps were produced by ethanol water solvolysis catalyzed by 0.005M or 0.01M H 2 SO 4 at 175°C. Condensation reactions of residual lignin occurred at a significant rate when the ethanol volume fraction was 0 % but not when it was ≥ 51 %. There was selective removal of uncondensed guaiacyl units when mixtures of 51 %, 76%, and 91% ethanol were used. The condensed units in the native lignin were less reactive and accumulated in the fibers. They constituted > 60 % of the C 9 units by the time 80 % delignification was achieved. A limited amount of results are presented for a kraft pulp with hopes of enhancing the credibility of permanganate oxidation as an analytical tool for residual lignins.

“…The permanganate oxidation method has shown that for softwoods, the residual lignins from kraft, soda (Gellerstedt and Lindfors 1984 a;Gellerstedt 1992), and organosolv (Lindner and Wegener 1990) pulping are more condensed than the corresponding native lignins. The method has also shown that uncondensod structures are selectively removed during oxygen delignification of kraft pulps (Gellerstedt 1992;Gellersledt et aL 1986).…”

Section: Introductionmentioning

confidence: 99%

Lignin Analysis by Permanganate Oxidation. I. Native Spruce Lignin

Bose¹,

Wilson²,

Francis³

et al. 1998

KeywordsPermanganate oxidation Lignin analysis Spruce lignin Uneondensed guaiacyl units Biphcnyls in spruce lignin [5-5 units in spruce lignin SummaryPermanganate oxidation has long been used to estimate the concentrations of uncondensed und condensed structures in phenolic lignin fractions. Four monomers and two dimcrs are normally (juunlified Cor softwood lignins and the actual yield of each is corrected for incomplete oxidation. Based on the analysis of several model compounds and lignin samples the correction factors were refined to give a better correlation between the original phenolic hydroxyl (PhOll) content and the tola I yield of selected products. An alkaline CuO presentment was used to hydroly/e most of the interunitury ether bonds in the lignin of spruce wood meat. The PhOM content increased from 12/100 G, units to 69/100 C; units. A composition of approximately 55% uncondensecl guaiacyls, 18% biphenyls and 14% ß-5 was estimated from KMnO 4 oxidation of this sample. Pulp-or WoodmealBenzole acid methyl exterx Flg. 1. Reaction sequence for the oxidative degradation of lignin by potassium permanganate und hydrogen peroxide (Gellerstedt 1992).