| 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. |
- 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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| 3. |
- 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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| 4. |
- 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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| 5. |
- 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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| 6. |
- 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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| 7. |
- 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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| 8. |
- 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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