Die massenspektrometrische Fragmentierung von Neopentylpolyolestern. 1—Pentaerythrittetrafettsäureester

The fragmentation of the homologous fatty acid tetraesters of pentaerythritol (C-2 to C-14) upon electron impact was investigated. The main fragment ions are [M? RCOO]⁺ and [M? RCOOH]⁺, for which cyclic acetal structures are postulated. Subsequent fragmentation was elucidated by ‘direct analysis of daughter ion’ (DADI) measurements and high resolution measurements. Esters of branched fatty acids can be distinguished from esters of n-fatty acids by characteristic ions. Isomeric esters of n-fatty acids cannot be separated by gas chromatography but identification is also possible by mass spectrometry.     

Ringerweiterung in organischen Molekeln unter Elektronenbeschuss: Die massenspektrometrische Fragmentierung von 2,3-dicarbalkoxy-spiro-cyclopropan-1, 9′-fluorenen

Ring Expansion of a three- to a five-membered cyclic structure in conjunction with loss of a carbalkoxy radical from the molecular ions is postulated for a series of 2,3-dicarbal-koxy-spiro-cyclopropane-1,9′-fluorenes. Initial rupture of the strained spiro-cyclopropane system with destruction of the distinct molecular geometry is inferred from virtually identical spectral patterns of, cis- and trans-isomers, whereas reclosure of the ‘open’ intermediate to a cyclopentadiene ring can be deduced from the secondary decomposition of the resulting (M–COOR) fragments. These latter ions exhibit loss of the second carbalkoxy group together with a hydrogen atom of unusual positional origin (1′ or its equivalent 8′) to form a pair of neutral species, ROH and CO. Since the ejection of hydrogen from aromatic positions can be taken as evidence of rearomatisation in the course of substitution, this origin is liable to mark the site of the new ring junction and thus to reflect the size of the enlarged cyclic moiety.     

Die massenspektrometrische Identifizierung von Alkyl-1, 3-thiazolen

Positional isomers of mono-, di- and trialkyl-1,3-thiazoles can be identified unequivocally by their electron impact mass spectra and differentiated from their isomers. The decisive criteria for this are the m/e values and the relative abundances of significant ions, in particular of the molecular ions, the [M – 1]⁺ ions, the thiazolylmethyl carbocations or their ring expanded thiazinium structures, and also of the thiiren radical ions which are formed upon the elimination of a nitrile molecule with ring contraction. In this way, 22 thiazole derivatives have been identified in the glass capillary gas chromatogram of aroma constituents of roasted coffee using a gas chromatograph mass spectrometer system. The structural correlations are substantiated by comparative measurements with a series of authentic samples.     

Cobalt- und Rhodiumphthalocyanine mit O-, S- und Se-Donorliganden

Phthalocyanines of Cobalt and Rhodium with O, S, and Se Donor Ligands Di(phenolato)-, -(benzenethiolato)- and -(benzeneselenonato)phthalocyaninatocobaltate(III) and -rhodate(III) are prepared by the reaction of di(hydroxo)phthalocyaninatometalate with phenol resp. benzenethiol or benzeneselenol and isolated as poorly soluble tetra(n-butyl)ammonium salts of the formula (ⁿBu₄N)[M(EPh)₂Pc^2?] (M = Co, Rh; E = O, S, Se). In the Uv-vis spectra π–π* transitions in the Pc^2?-typical B, Q, N and L regions are observed. For the Rh-complexes with E = S, Se there is a further band at 18.0 kK due to excitonic π(Ph)–π(Pc) interactions. The (E→Rh-charge-transfer(CT)) transition is observed for E = Se at 26.0 kK, being obscured by the Q, N region for E = O, S. The strong, broad (E → Co? CT) transition (E = O, S, Se) absorbs at ～20.5 kK. A second CT-transition is detected within the Q, N region for E = S, Se. Molecular vibrations (in cm^?1) are examined by m.i.r., f.i.r, FT-Raman and dispersive resonance-Raman(RR) spectra. The C? E stretching mode (v_7a) of the axial EPh ligands is observed for E = O at 1256/1262, 1269 (Co, m.i.r./RR), 1246/1265 (Rh), for E = S at 1085 (Co, Rh; RR) and for E = Se at 1069 (Co, Rh; RR). The C? C? E deformation mode (v_6a) is assigned for E = O at 554/557 (Co, RR), 568 (Rh, RR) and for E = S at 420 (Co, Rh; RR). The following vibrational modes of the trans-ME₂N₄ skeleton are assigned: v_s(ME) for Co: 381 (O)/271 (S)/139 (Se); for Rh: 408/297/156; v_as(ME) for Co: 352/277/235; for Rh: 391/278/225; v_as(MN) absorbs nearly independent of M and E at ～325 (f.i.r.) M? E? C deformation modes are observed between 246 and 200 (f.i.r.) resp. 217 and 186 (RR).     

含O-, S-, N-和C-2,3-不饱和糖苷的合成

以3,4,6-三-O-乙酰基-D-葡萄烯糖为原料,(NH₄)₂S₂O₈为催化剂,利用Ferrier重排反应制得一系列含O-, S-,N-和C-2,3-不饱和糖苷,其结构经¹H NMR, IR和MS（ESI）确证。考察了催化剂及其用量,溶剂和温度对产率的影响。结果表明：在最优条件［反应温度80 ℃,乙腈为溶剂,(NH₄)₂S₂O₈为催化剂(1 eq.)］下,3a产率高达83%。     

Die massenspektrometrische Bestimmung von Deuterium in Helium

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Die massenspektrometrische Bestimmung von Kohlendioxidspuren in Gegenwart von Sauerstoff

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Die spektrophotometrische Bestimmung von Thiolen und Disulfiden mit N-?thylmaleinimid

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Die heterolytische Fragmentierung von Benzoin-O-(carbamoyl)oximen

The Heterolytic Fragmentation of Benzoin-O-(carbamoyl)oximes While the known heterolytic fragmentation reactions give only three, thermal decomposition of benzoin-O-(carbamoyl)oximes results in at least four fragments: nitrile or isocyanide, carbonyl compound, CO₂ and amine. This exception is due to the transformation of the nucleofugal group 3 into the unstable carbamic acid and its decomposition (s. Scheme 1). Since only the configuration of benzoin (E)-O-(carbamoyl)oximes is satisfactory for concerted reactions, we conclude that the nitrile producing fragmentation of these (E)-compounds is concerted, whereas in the isocyanide producing fragmentation of the corresponding (Z)-compounds several steps are involved. – In contrast to the benzoin-O-(carbamoyl)oximes the pyrolysis of benzil-(E)-O-(methylcarbamoyl)oxime starts with the elimination of methyl isocyanate and the following fragmentation is that of the oxime.     

Cyclocondensation of 1-Tosyl-2,2-dichloroethenyl Isothiocyanate with O-, S-, N-, and C-Nucleophiles

Treatment of 1-tosyl-2,2-dichloroethenyl isothiocyanate with alcohols, thiols, primary and secondary amines, hydrazine and its derivatives, and phosphonium ylides results in addition of the O-, S-, N-, or C-nucleophilic center to the isothiocyanate group, followed by cyclocondensation with elimination of hydrogen chloride and formation of the corresponding 2-functionally substituted 4-tosyl-5-chloro-1,3-thiazoles. Further transformations of these compounds were studied, and a series of previously unknown types of 3-functionally substituted 1,3-thiazole derivatives were prepared.     

Die massenspektrometrische Bestimmung von Alkoholen in Produkten der Fischer-Tropsch- Synthese

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Die Submikrobestimmung von O- und N-Acetylgruppen organischer Verbindungen

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Die massenspektrometrische Analyse aliphatischer Aldehyde

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Die quantitative Bestimmung des H-, C-, N-, O- und F-Gehaltes in organischen Verbindungen

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Die Hochfrequenztitration von Silber mit

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Elektronenstossinduzierte Fragmentierung von Trimethyl-Benzaldehyden

Using deuterium- and ¹³C-labelled trimethylbenzaldehydes the unusual fragmentation pattern of these compounds has been elucidated. Statistical calculations show that in this case the carbon-atoms are not equilibrated as the hydrogen-atoms, regarding the elimination of C₂H₄.     

Die quantitative Bestimmung von O- und N-Acetylgruppen in Zuckerhydrazonacetaten

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Die Bestimmung von Hexosephosphaten mit Hilfe von Anthron

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Die Reaktion von organischen Peroxiden mit N,N-Dimethyl-p-phenylendiaminsulfat

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