| 1. |
- Larsson, Kenneth, et al.
(författare)
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Methanolysis of galacturonic acid
- 1974
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Ingår i: Carbohydrate Research. ; 34, s. 323-329
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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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| 2. |
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| 3. |
- Petersson, Göran, 1941
(författare)
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Branched deoxyaldaric acids from alkaline degradation of carbohydrates: Structure determination by mass spectrometry of trimethylsilyl derivatives
- 1975
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Ingår i: Carbohydrate Research. ; 43, s. 1-8
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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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| 4. |
- Petersson, Göran, 1941, et al.
(författare)
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Formation of 1,4-anhydro-3-deoxypentitol-2-carboxylic acids by alkaline degradation of cellulose
- 1976
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Ingår i: Acta Chemica Scandinavica B. ; 30, s. 27-30
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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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| 5. |
- Havlicek, Jaroslav, et al.
(författare)
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Partition chromatography and mass spectrometry of tetrulose and pentuloses
- 1972
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Ingår i: Acta Chemica Scandinavica. ; 26, s. 2205-2215
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Tidskriftsartikel (refereegranskat)abstract
- Partition chromatography on ion exchange resins in aqueous ethanol is an excellent tool for the separation of tetrulose and pentuloses for both analytical and preparative purposes. The analysis of complex mixtures is facilitated by the fact that the ketoses are recorded by both the orcinol and periodate-formaldehyde methods whereas under proper conditions aldoses are only recorded in the orcinol channel. In gas chromatography the trimethylsilylated 3-pentuloses gave rise to only one prominent peak which as revealed by mass spectrometry corresponded to the keto form. Tetrulose and the 2-pentuloses gave two or more peaks. The 1,2-enediol derivative obtained from tetrulose was identical with that recorded for threose.
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| 6. |
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| 7. |
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| 8. |
- 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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| 9. |
- 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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| 10. |
- 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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| 11. |
- Mattsson, Mary, 1945, et al.
(författare)
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Reference GLC data for the analysis of phenolic compounds as trimethylsilyl derivatives
- 1977
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Ingår i: Journal of Chromatographic Science. - 0021-9665. ; 15, s. 546-554
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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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| 12. |
- Nordén, Bengt, 1945
(författare)
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Applications of linear Dichroism Spectroscopy
- 1978
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Ingår i: Applied Spectroscopy Reviews. - : Informa UK Limited. - 1520-569X .- 0570-4928. ; 14:2, s. 157-248
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Tidskriftsartikel (refereegranskat)abstract
- Linear dichroism is the phenomenon of anisotropic absorption of light. It is shown by materials containing oriented molecules for which the absorption varies with the direction. The absorption intensity is proportional to the square of the scalar product between the electric field vector of the light and a molecule-characteristic transition moment vector, the absorption being maximum when the light vector is polarized parallel to the transition moment and zero when perpendicular to it. Linear dichroism can therefore provide (1) directions of transition moments when the molecule orientation is known (spectroscopic applications), or (2) information on molecular orientation when the transition moments are known (structural applications). Both applications are useful in several chemical systems, but so far the use of linear dichroism has been confined to a relatively small number of specialized laboratories, not least because of a lack of appropriate commercial instruments. Plane-polarized spectra have long been measured on crystals and other well-oriented materials, but systems with less complete orientation have usually been studied by birefringence which has allowed greater sensitivity. Birefringence and linear dichroism are related by the dispersion equations and therefore in principle contain the same basic information. However, linear dichroism is better suited for practical use since it is related in a very simple way to more-or-less well-separated quantal transitions, while birefringence is a complicated average over all transitions in the molecule.
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| 13. |
- Petersson, Göran, 1941
(författare)
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A McLafferty - type rearrangement of a trimethylsilyl group in silylated hydroxy carbonyl compounds
- 1972
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Ingår i: Organic Mass Spectrometry. ; 6, s. 577-592
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Tidskriftsartikel (refereegranskat)abstract
- A McLafferty-type rearrangement of a trimethylsilyl group is demonstrated. Abundant rearrangement ions are formed for trimethylsilyl derivatives of alpha,beta-dihydroxy carbonyl compounds. Data are given for a large number of hydroxy acids and hydroxy ketones including aldonic acids, aldaric acids, acyclic ketoses and hydroxy keto acids. A few branched lactones are also shown to rearrange. The positive charge and the unpaired electron are extensively delocalized in the odd-electron rearrangement ions. Those substituents at the alpha-carbon atom which offer a favourable delocalization promote the rearrangement. Spectra of specifically methylated species reveal that migration over larger than six-membered rings occurs to some extent. An observed dependence of abundance on configuration is associated with steric strains in the transition state. The rearrangement ions are of great diagnostic value in structural analysis. They are relatively more abundant at low electron energies and give rise to the base peak at 20 eV for many compounds. Ions produced by the competing conventional McLafferty rearrangement are less abundant.
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| 14. |
- Petersson, Göran, 1941
(författare)
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Carbohydrate - related hydroxy carboxylic and dicarboxylic acids as trimethylsilyl derivatives
- 1977
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Ingår i: Journal of Chromatographic Science. - 0021-9665. ; 15, s. 245-255
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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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| 15. |
- Petersson, Göran, 1941
(författare)
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Conversion of dehydroascorbic acid to a branched hexaric acid in neutral and alkaline aqueous solution
- 1976
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Ingår i: Analytical Biochemistry. - : Elsevier BV. - 0003-2697. ; 72, s. 623-628
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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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| 16. |
- Petersson, Göran, 1941
(författare)
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Gas-chromatographic analysis of sugars and related hydroxy acids as acyclic oxime and ester trimethylsilyl derivatives
- 1974
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Ingår i: Carbohydrate Research. ; 33, s. 47-61
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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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| 17. |
- Petersson, Göran, 1941
(författare)
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Gas chromatography - mass spectrometry of sugars and related hydroxy acids as trimethylsilyl derivatives
- 1974
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The application of gas chromatography and mass spectrometry has contributed to the rapid progressof carbohydrate chemistry during the past ten years. Themethods are indispensable tools in current research oncarbohydrate reactions during pulping processes.Acyclic ether, ester, and oxime trimethylsilyl derivatives are useful for gas chromatographic analysis of alditols, aldoses, ketoses, aldonic acids, aldaric acids and uronic acids. These derivatives have been studied in detail by mass spectrometry and shown to be advantageous for structural analysis. The mass spectrometric fragmentation of glycosidic trimethylsilyl derivatives has also been investigated. An important application is the identification of products from methylation analysis.
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| 18. |
- Petersson, Göran, 1941
(författare)
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Mass spectrometry of aldonic and deoxyaldonic acids as trimethylsilyl derivatives
- 1970
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Ingår i: Tetrahedron. ; 26, s. 3413-3428
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Tidskriftsartikel (refereegranskat)abstract
- Open-chain trimethylsilyl derivatives of aldonic and deoxyaldonic acids, which can be prepared from salts of the acids, are well suited for structure determination by mass spectrometry. The study is focussed on aldonic and unbranched monodeoxyaldonic acids, but several dideoxyaldonic and branched deoxyaldonic acids are included. Spectra of the derivatives of glycolic, lactic and hydracrylic acids are discussed.The structural isomers exhibit interpretable differences, whereas the spectra of the diastereomers are similar. The molecular weight and the number of OH groups can be deduced from the spectra, as well as the position of the “deoxy group” in unbranched deoxyaldonic acids. The most prominent fragmentations are α-cleavages of the carbon chain, frequently followed by rearrangement loss of trimethylsilanol. A structurally significant McLafferty-type rearrangement of a trimethylsilyl group is described. Several types of ions decompose by expulsion of small molecules such as CO, CH2O and CO2.
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| 19. |
- Petersson, Göran, 1941
(författare)
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Mass spectrometry of hydroxy dicarboxylic acids as trimethylsilyl derivatives. Rearrangement fragmentations.
- 1972
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Ingår i: Organic Mass Spectrometry. ; 6, s. 565-576
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Tidskriftsartikel (refereegranskat)abstract
- Gas chromatography - mass spectrometry offers a convenient method for the separation and identification of hydroxy dicarboxylic acids as open-chain trimethylsilyl (TMS) derivatives. Mass spectra were studied of aldaric (tartronic, tartaric, pentaric and hexaric) acids and deoxyaldaric (malic, 2-deoxypentaric, 2-deoxyhexaric, 3-deoxypentaric and 3-deoxyhexaric) acids. The different structural types can be readily identified from their characteristic spectra. The most prominent fragmentations involving the rupture of one bond are the loss of a siliconlinked methyl group and the formation of alfa-cleavage ions by carbon chain cleavage. The further decay is characterized by a number of significant rearrangements specific of TMS derivatives. Several of these can be classified as involving migration of a TMS group to an oxygen atom or migration of an ester OTMS group to a silicon atom. Concomitant loss of a stable molecule often provides a driving force. Prominent odd-electron ions are formed by a McLafferty-type rearrangement of a TMS group. The decomposition of several even-electron ions can be regarded as analogous to that rearrangement.
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| 20. |
- Petersson, Göran, 1941
(författare)
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Reference mass spectra of hexoses and methylated hexoses
- 1970
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Ingår i: Archives of Mass Spectral Data. ; 1, s. 624-665
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Tidskriftsartikel (refereegranskat)abstract
- Certified mass spectra (70 eV) as tables of relative abundance and as bar graphs are given for trimethylsilyl derivatives of aldohexoses. From specific fragment ions, the number and position of O-methyl groups can be assessed for unknown methylated hexoses as outlined in a previous article (link).
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