Branched deoxyaldaric acids from alkaline degradation of carbohydrates: Structure determination by mass spectrometry of trimethylsilyl derivatives

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

Gas chromatography - mass spectrometry of sugars and related hydroxy acids as trimethylsilyl derivatives

The application of gas chromatography and mass spectrometry has contributed to the rapid progress of carbohydrate chemistry during the past ten years. The methods are indispensable tools in current research on carbohydrate reactions during pulping processes.<p> 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

Mass spectrometry of alditols as trimethylsilyl derivatives

Trimethylsilyl ethers of alditols with 3, 4, 5 and 6 C atoms were investigated. The mass spectra are unusually clearly correlated with the structures. The predominant fragmentations are cleavages in the carbon chain and rearrangement loss of trimethylsilanol. The spectra are closely related to those of the methyl ethers. A spectrum unambiguously identifies a compound as an alditol and permits the determination of its molecular weight

Mass spectrometry of aldonic and deoxyaldonic acids as trimethylsilyl derivatives

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.<p> 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

Gas-chromatographic analysis of sugars and related hydroxy acids as acyclic oxime and ester trimethylsilyl derivatives

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

High ambient concentrations of monoterpenes in a Scandinavian pine forest

Total monoterpene levels of the order of 100 μg/m3 were assessed in the summer night air of a typical young planted forest of Scots pine (Pinus silvestris) in Sweden. These concentrations are much higher than those reported in previous studies of ambient monoterpenes. Predominant species were α-pinene and 3-carene. Camphene, β-pinene, myrcene, β-phellandrene and limonene were other prominent components determined. The monoterpenes were shown to originate almost exclusively from Scots pine and the proportions between them to be characteristic of this conifer species

Conversion of dehydroascorbic acid to a branched hexaric acid in neutral and alkaline aqueous solution

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

Sukralos och sötningsmedel

Det klorinnehållande sötningsmedlet sukralos belyser klart riskerna med naturfrämmande kemiska ämnen i livsmedel. Sukralos sprids via reningsverk ut i miljön och kan rimligen inte få godkännas enbart av livsmedelsmyndigheter. Marknadsföringen av sukralosprodukter har hittills knappast uppfyllt rimliga etiska krav på saklighet. Det ökade sötmaberoendet är ett starkt skäl för avveckling av inte bara sukralos utan även andra syntetiska sötningsmedel. Näringslivet har stort intresse av och stora möjligheter att gå i spetsen för en avveckling av sötningsmedel och söta drycke

Fetter - Kolesterol - Statiner

<ul> <li>Snabba kolhydrater orsakar fetma genom att insulin styr inlagring av fett. Socker plus fett som i glass ger därför snabb viktökning.</li> <p/> <li>Mättat fett i bland annat smör och ost har tidigare antagits orsaka ateroskleros. Även margariner som Lätta innehåller mättat fett, men har en för människor onaturlig sammansättning av triglycerider.</li> <p/> <li>Halten kolesterol i blodfetter reglerar kroppen själv till bästa nivå. Ateroskleros orsakas inte av kolesterol utan beror på kostrelaterade kemiska skador på proteiner och fleromättat fett i LDL och HDL.</li> <p/> <li>Statiner blockerar biosyntes av inte bara kolesterol utan även av Q10 vilket försvagar muskler och hjärta. Antioxidanter och omega-3 (som EPA), samt mindre socker och omega-6 skyddar blodkärl naturligt.</li> </ul