Acid Degradation of Lignin. Part VIII. Low Moleculr Weight Phenols from Acidolysis of Birch Lignin.

Wood Based Lignin Reactions Important to the Biorefinery and Pulp and Paper Industries

“…The most important reaction during acidolysis of lignin is the cleavage of the β-O-4 bonds. This cleavage reaction has been described by several authors (Adler et al 1957;Lundquist and Lundgren 1972;Lundquist 1973;Ito et al 1981;Yasuda et al 1981aYasuda et al , b, 1982Yasuda et al , 1985Hoo et al 1983;Karlsson et al 1988). The mechanism for this cleavage reaction (as reported by Lundquist and Lundgren) is shown in Fig.…”

Revisiting the Mechanism ofβ-O-4 Bond Cleavage during Acidolysis of Lignin. Part 2: Detailed Reaction Mechanism of a Non-Phenolic C6-C2Type Model Compound

“…The elementary reaction steps in the β-O-4 bond cleavage of V G during acidolysis can reasonably be assumed on the basis of the contents of earlier papers, [2][3][4][5][6][7][8][9][10][11][12][13][14] and the steps are shown in Figure 2. The initial step is protonation of the α-hydroxyl group (step I) followed by the release of water affording a benzyl cation-type intermediate (BC in Figure 2, step II).…”

“…Presumed elementary reaction steps of V G during the acidolysis on the basis of the contents of earlier papers. [2][3][4][5][6][7][8][9][10][11][12][13] 274 Downloaded by [Erciyes University] at 22:37 04 January 2015 ratio is 3.9 in this study, step III is probably the major route. Further discussion of the predominance of step III over step V is as follows.…”

“…The β-O-4 bond cleavage during the acidolysis of lignin has been discussed in several papers, [2][3][4][5][6][7][8][9][10][11][12][13] and the mechanism involved and the rate-determining step have been suggested. [3] However, because the hypothesized mechanism does not appear to explain the dependence of the acidolysis rate on the type of acid applied, [13,14] we reexamined the mechanism involved and published a paper on the reaction route of a C 6 -C 2 dimeric non-phenolic β-O-4 type lignin model compound, 2-(2-methoxyphenoxy)-1-(3,4-dimethoxyphenyl)ethanol (veratrylglycol-β-guaiacyl ether, V G in Figure 1).…”

Size Exclusion Chromatography of Lignins Using Lithium Chloride/N,n-Dimethylacetamide as Mobile Phase. I. Dissolved and Residual Birch Kraft Lignins

“…In acidolysis experiments, birch lignins have been reported to have more acid labile ether linkages than spruce. 27 Using oxidative degradation of the phenolic moiety, no evidence for extensive condensation of residual lignin during acid dioxane extraction of birch pulp has been found. 22 Consequently, in spite of the milder conditions used during acid dioxane extraction compared with acidolysis, a certain degradation of the residual lignin obtained in this study cannot be ruled out.…”