| 61. |
- Löwendahl, Lars, 1940, et al.
(författare)
-
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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| 62. |
- Mattsson, Mary, 1945, et al.
(författare)
-
Reference GLC data for the analysis of phenolic compounds as trimethylsilyl derivatives
- 1977
-
Ingår i: Journal of Chromatographic Science. - 0021-9665. ; 15, s. 546-554
-
Tidskriftsartikel (refereegranskat)abstract
- Comprehensive reference GLC data are given for trimethylsilyl derivatives of about 130 aromatic compounds grouped as phenols and naphthols, alcohols, carboxylic acids, aldehydes and ketones, and chloro compounds. The aldehydes and ketones were analysed as both oxime and O-methyl oxime derivatives. Retention data on methyl and phenyl silicone columns are given as MU values in temperature-programmed analysis. Correlations between structure and retention are interpreted in terms of MU increments of structural elements. Methods for predicting MU values are proposed. Diagrams based on differences in MU between the two silicone phases aid in qualitative analysis. Approximate FID relative molar response values were estimated from the atomic composition of the derivatives.
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| 63. |
- Petersson, Göran, 1941
(författare)
-
Carbohydrate - related hydroxy carboxylic and dicarboxylic acids as trimethylsilyl derivatives
- 1977
-
Ingår i: Journal of Chromatographic Science. - 0021-9665. ; 15, s. 245-255
-
Tidskriftsartikel (refereegranskat)abstract
- Retention index and relative retention were determined for trimethylsilyl esters/ethers of approximately 170 acids and lactones. The structural categories studied were aldonic (hydroxy monocarboxylic) acids, aldaric (hydroxy dicarboxylic) acids, non - carbohydrate (mainly dicarboxylic) acids, and lactones of aldonic acids. Data are given for the silicone stationary phases OV-1 (methyl), OV-17 (50% phenyl) and QF-1 (50% trifluoropropyl). Diagrams of the retention index on the non-polar phase versus the increase in the retention index on either of the other phases are useful for qualitative analysis. The dependence of retention on structure is interpreted in terms of non-polar and polar interactions between solute and stationary phase. Structural units of the solutes are attributed retention index increments which permit predictions of retention from structure or structure from retention. The reference retention index data can be used in temperature - programmed analalysis if retentions are measured as methylene unit (MU) values. Differences between the retention index and MU concepts are discussed.
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| 64. |
- Petersson, Göran, 1941
(författare)
-
Conversion of dehydroascorbic acid to a branched hexaric acid in neutral and alkaline aqueous solution
- 1976
-
Ingår i: Analytical Biochemistry. - : Elsevier BV. - 0003-2697. ; 72, s. 623-628
-
Tidskriftsartikel (refereegranskat)abstract
- Dehydroascorbic acid is shown to be converted to 2-(threo-1,2,3-trihydroxypropyl)tartronic acid in aqueous alkaline solutions. The structure of the acid was determined by mass spectrometry of its acyclic Me3Si derivative. Mass spectrometric and chromatographic data are compared with those of related compounds. The acid is formed by a benzilic acid rearrangement of the intermediate 2,3-hexodiulosonic acid. The rate of formation at 38°C was studied quantitatively by glc. It increases at increased alkalinity but is significant even at physiological pH. The presence of oxygen does not substantially influence the reaction.
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| 65. |
- Petersson, Göran, 1941, et al.
(författare)
-
Formation of 1,4-anhydro-3-deoxypentitol-2-carboxylic acids by alkaline degradation of cellulose
- 1976
-
Ingår i: Acta Chemica Scandinavica B. ; 30, s. 27-30
-
Tidskriftsartikel (refereegranskat)abstract
- An anhydroisosaccharinic acid obtained in large amounts by end-wise degradation of cellulose in alkaline media, and in small amounts in hydrolysates of cellulose, has been identified as a 1,4-anhydro-3-deoxypentitol-2-carboxylic acid (3-hydroxy-5-(hydroxymethyl)oxolane-3-carboxylic acid). Structural evidence was obtained by GC-MS studies of the compounds (as Me3Si derivatives) obtained on degradation of the acid to 1,4-anhydro-3-deoxypentitol by reduction of the methyl ester followed by periodate oxidation and borohydride reduction. In aqueous alkali, the acid is likely to be formed from a dicarbonyl precursor by benzilic acid rearrangement.
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| 66. |
- Löwendahl, Lars, 1940, et al.
(författare)
-
Dicarboxylic acids produced by oxygen-alkali treatment of birch xylan
- 1975
-
Ingår i: Acta Chem. Scand. B. ; 29:4, s. 526-527
-
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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| 67. |
- Löwendahl, Lars, 1940, et al.
(författare)
-
Oxygen-alkali treatment of cellobiose
- 1975
-
Ingår i: Acta Chem. Scand. B. ; 29:9, s. 975-980
-
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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| 68. |
- Petersson, Göran, 1941
(författare)
-
Branched deoxyaldaric acids from alkaline degradation of carbohydrates: Structure determination by mass spectrometry of trimethylsilyl derivatives
- 1975
-
Ingår i: Carbohydrate Research. ; 43, s. 1-8
-
Tidskriftsartikel (refereegranskat)abstract
- The deoxyaldaric acids corresponding in structure to the 3-deoxy-2-C-(hydroxymethyl)aldonic (isosaccharinic) acids have been identified as products of treatment of various carbohydrates with alkali and oxygen-alkali. The structures of the acids were determined from the mass spectra of their Me3Si derivatives on the basis of previously known, specific fragmentation reactions. The g.l.c.-m.s. technique was used, and g.l.c. retention data are given. The identified species are 2-deoxy-3-C-(hydroxymethyl)tetraric, 3-deoxy-2-C-hydroxymethyl-erythro-pentaric, 3-deoxy-2-C-hydroxymethyl-threo-pentaric, 2-methyltartronic, 2-(2-hydroxyethyl)tartronic, and 2-(2,3-dihydroxypropyl)tartronic acids. Their formation from 4-O-substituted uronic and ulosonic acids is briefly discussed.
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| 69. |
- Larsson, Kenneth, et al.
(författare)
-
Methanolysis of galacturonic acid
- 1974
-
Ingår i: Carbohydrate Research. ; 34, s. 323-329
-
Tidskriftsartikel (refereegranskat)abstract
- Dimethyl acetals of galacturono-6,3-lactone and methyl galacturonate are formed during methanolysis of galacturonic acid. The products of methanolysis were studied by ion exchange and gas chromatography. Trimethylsilyl (TMS) derivatives were used in gas chromatography. Structure determinations were made from mass spectra of the TMS derivatives. The course of methanolysis was investigated by means of a gas chromatographic study of the composition of the reaction mixture as a function of time.
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| 70. |
- Petersson, Göran, 1941
(författare)
-
Gas-chromatographic analysis of sugars and related hydroxy acids as acyclic oxime and ester trimethylsilyl derivatives
- 1974
-
Ingår i: Carbohydrate Research. ; 33, s. 47-61
-
Tidskriftsartikel (refereegranskat)abstract
- A g.l.c. method which makes possible the simultaneous analysis of the common types of acidic and neutral sugars is described. Particular advantages are achieved with hydroxy acids, ketoses, and uronic acids. Acids and lactones are first converted into their sodium salts. Free or potential aldehydo and keto groups are transformed into oximes or O-methyloximes. Fully substituted acyclic ester and oxime trimethylsilyl derivatives are prepared with bis(trimethylsilyl)trifluoroacetamide and chlorotrimethylsilane. Syn and anti isomers of the oximes are formed, but a stationary phase can often be chosen on which the two peaks coincide. The silicone stationary phases OV-1, OV-17, QF-1, and XE-60 were used. Retention data are given for aldonic and deoxyaldonic acids, aldoses, ketoses, and uronic acids. Relationships between structure and retention are discussed. The derivatives are suited to structural analysis by gas chromatography—mass spectrometry.
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