Alkaline hydrogenation of lignin

The Structure of Dimers from the Alkaline Hydrogenation of Lignin... 

It appears justifiable to propose mechanisms for the formation of the monomeric and dimeric products of the alkaline hydrogenation of lignin. 

In summary, we have isolated and identified two dimeric compounds from the alkaline hydrogenation of sugar maplewood lignin—namely, 1,2-(4,4 -dihydroxy-3,3, 5,5 -tetramethoxydiphenyl)-ethane (I) l,2-(4,4 -... 

Bhattacharya A, Schuerch C (1960) Lignin from the alkaline hydrogenation of sugar maple-wood III Chromatographic separation of higher molecular weight fractions and a structural study TAPPI 43 840-844... 

We now wish to report our results on isolating lignin-derived dimers by alkaline hydrogenation and to propose mechanisms for their formation. In addition, we will present some information on the (NMR) spectra of these and related compounds this technique has been useful for analyzing the structure of lignin degradation products and related synthetic materials. 

The isolation of 2,2 -dihydroxy-3,3 -dimethoxy-5,5 -dialkylbiphenyls from both neutral (IS) and alkaline hydrogenation supports Pew s proposal that the biphenyl structure is of considerable importance in lignin... 

Coniferaldehyde structures are the major leucochromophore present in spruce lignin. These end groups are also present to a large extent in unbleached mechanical pulps and are responsible for a major portion of the absorption of UV-radiation above 350 nm. Mild sulfite treatment leads to a considerable reduction in the content of coniferaldehyde structures. After bleaching of mechanical and chemimechanical pulps with alkaline hydrogen peroxide, coniferaldehyde structures are to a large extent eliminated and they cannot be considered to be major contributor to the photo-... 

Lee, D.Y. and Sumimoto, M., "Mechanochemistry of Lignin. V. An Intensive Chromophore in Mechanical Pulps Bleached With Alkaline Hydrogen Peroxide", Hokforschmg, 1991, 45 (Supplement), 15. 

Gierer, J., and Imsgard, F. (1977). The reactions of lignins with oxygen and hydrogen peroxide in alkaline media. Sven. Papperstidn. 80, 510-518. 

Corbett JF (1966) The chemistry of hydroxyquinones. Part I. The reaction of 2-hydroxybenzoquinones with alkaline hydrogen peroxide. J Chem Soc (C) 2308-2311 Corbett JF, Fooks AG (1967) The chemistry of hydroxy-quinones. Part III. The reactions of 2,5-dihydroxy-benzoquinones with alkali. J Chem Soc (C) 1909-1913 Dence CW (1971) Halogenation and nitration. In Sarkanen KV, Ludwig CH (eds) Lignins. 

M.B. Hocking and J.P. Crow, On the Mechanism of Alkaline Hydrogen Peroxide Oxidation of the Lignin Model p-Hydroxyacetophenone. Can. J. Chem. 72, 1137-1142 (1994). 

G Gellerstedt, HL HardeU, and EL Lindfors. The Reactions of Lignin with Alkaline Hydrogen Peroxide. Part fV. Products from the Oxidation of Quinone Model Compounds. Acta Chem. Scand. B 34 669-673, 1980. 

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