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| 2. |
- Löwendahl, Lars, 1940, et al.
(författare)
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Dicarboxylic acids produced by oxygen-alkali treatment of birch xylan
- 1975
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Ingår i: Acta Chem. Scand. B. ; 29:4, s. 526-527
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Tidskriftsartikel (refereegranskat)abstract
- C-(2-Hydroxyethyl)tartronic acid is predominant among the dicarboxylic acids and its formation in 12 % yield makes it a major product from xylan. The structure indicates that it is formed from terminal, oxidized xylose units by beta-elimination at C-4 and subsequent benzilic acid rearrangement. It is proposed that 2-ulosonic acid end-groups or ulosono-1,5-lactone end-groups, related in structure to ascorbic acid, are formed as precursors.
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| 3. |
- Löwendahl, Lars, 1940, et al.
(författare)
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Oxygen-alkali treatment of cellobiose
- 1975
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Ingår i: Acta Chem. Scand. B. ; 29:9, s. 975-980
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Tidskriftsartikel (refereegranskat)abstract
- C-(2,3-Dihydroxypropyl)tartronic acid is a major dicarboxylic acid formed during O2-NaOH and O2-NaHCO3 treatment of cellobiose. The observation that this acid is the main reaction product after alkali treatment ofascorbic acid in O2-free medium supports the conclusion that it is formed via an aglycon moiety related to ascorbic acid. Other dicarboxylic acids from cellobiose are oxalic, tartronic, deoxytetraric, C-(hydroxymethyl)tartronic, and succinic acids.The temperature, pH and additions of iron and cobalt salts strongly influence the product composition. The formation of aldobionic acids from cellobiose parallels the formationof aldonic acid end groups during oxygen bleaching of cellulose.
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| 4. |
- Löwendahl, Lars, 1940, et al.
(författare)
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Phenolic compounds in kraft black liquor
- 1978
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Ingår i: Svensk Papperstidning. ; 81:12, s. 392-396
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Tidskriftsartikel (refereegranskat)abstract
- The prominent phenolic compounds with one aromatic ring in kraft black liquor were analysed by a combination of liquid chromatography, gas chromatography and mass spectrometry. Extracted spruce meal was cooked both under mild, conventional conditions and under extremely severe conditions. In all, the analyzed phenolic compounds amounted to 0.6 kg per 100 kg of dry wood under conventional conditions. In addition to 2-methoxyphenol, vanillin and 4-hydroxy-3-methoxyacetophenone, several phenolic alcohols and carboxylic acids with the same aromatic substitution were isolated and identified. The yield of related 3,4- dihydroxyphenylsubstituted compounds increased under severe conditions.
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