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  • Analytical Chemistry and Spectroscopy  (503)
  • Inorganic Chemistry  (286)
  • Physics  (75)
  • Theoretical, Physical and Computational Chemistry  (28)
  • Wiley-Blackwell  (892)
  • 1
    Electronic Resource
    Electronic Resource
    Monitoring the behaviour of 4-ketocyclophosphamide versus cyclophosphamide during capillary gas chromatography by mass spectrometry (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 643-647 
    Details
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Capillary Gas Chromatography (CGC) is capable of determining underivatized cyclophosphamide (CPA) using SCOT OV 275 columns. Then CPA is subjected to in situ degradation resulting in formation of a cyclization product which can be determined selectively in biological fluids. In routine bioanalysis however cyclization products of CPA metabolites might interfere, e.g. 4-keto CPA. In the present study possible formation of cyclization products of 4-keto CPA similar to CPA was monitored by Mass Spectrometry. Cyclization of 4-keto CPA in situ was demonstrated to occur, resulting in a product similar to that of CPA. Both cyclization products could be determined selectively and it appeared that in situ cyclization of 4-keto CPA was negligible (〈5%), probably owing to extra stabilization of the CPA metabolite by keto-enol tautomerism as has been demonstrated by NMR.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200141113
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  • 2
    Electronic Resource
    Electronic Resource
    A study of some deactivation methods for fused silica capillary columns by CP-MAS NMR and capillary gas chromatography (1985)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 8 (1985), S. 664-672 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography, GC ; Fused silica capillary columns ; CP-MAS NMR ; Deactivation methods ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of deactivating a fused silica surface by silylation with 1,1,3,3-tetraphenyl-1,3-dimethylilazane (TPDMDS), triphenylsilylamine (TPSA), and octamethylcyclotetrasiloxane (D4) and by polydimethylsiloxane degradation (PSD) is studied. Rehydrated, dried, and deactivated Cab-O-Sil M5 samples are used as model materials for 29Si CP-MAS NMR analysis.At about 350 °C, TPDMDS yelds mainly diphenylmethylsiloxysilane, dimethyldisiloxysilane, and triphenylsiloxysilane groups. TPSA yields phenyltrisiloxysilane, diphenyldisiloxysilane, and triphenylsiloxysilane groups. At 400°C, the products formed initially are eventually replaced by methyltrisiloxysilane or phenyltrisiloxysilane groups, while a substantial number of silanol groups still remains. The possible consequences for wettability are discussed.D4 reacts with Cab-O-Sil even at 200°C, but a large number of silanol groups remains. This number decreases gradually at higher temperatures and becomes negligible above 400°C. The formation of methyltrisiloxysilane groups, which starts at 425°C, is predominant at 490°C.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240081005
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  • 3
    Electronic Resource
    Electronic Resource
    A CP-MAS NMR study of some deactivation methods in capillary gas chromatography (1984)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 7 (1984), S. 607-614 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography, GC ; Fused silica capillary columns ; CP-MAS NMR ; Silylation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of temperature, water content, and the type of reagent on the silylation of fused silica capillaries was studied by 29Si and 13C CP-MAS NMR. Fumed silica (Cab-O-Sil M5), which is essentially a highly dispersed vitreous quartz with a surface comparable to that of fused silica capillary columns, was selected as a model material.Hexamethyldisilazane (HMDS) and 1,2-diphenyl-1,1,3,3-tetraphenyldisilazane (DPTMDS), which were used as silylation reagents, yielded trimethyl- and dimethylphenylsilyl surface groups respectively at lower temperatures (〈 350°C and 〈250°C respectively). At higher temperatures, increasingly more dimethylsilyl groups are formed, with the silicon bound to two oxygen atoms. This process occurs for DPTMDS at a considerably lower temperature than for HMDS. The formation of silyl groups on the surface and the disappearance of hydroxyl groups are followed independently. The 13C NMR and GC-MS of the reaction products showed that with DPTMDS, the formation of two Si-O-Si links is accompanied by a loss of phenyl groups rather than of methyl groups.After the Cab-O-Sil had been dried over P2O5, the formation of these double links occurred for HMDS only at temperatures above 460°C and for DPTMDS at 400°C. Thus we concluded that water supplies oxygen atoms for double Si-O-Si links (possibly crosslinks) necessary for efficient deactivation. This may explain the less successful silanization of fused silica capillaries because their water content is lower than that of glass capillaries.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240071102
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  • 4
    Electronic Resource
    Electronic Resource
    Identification of oplopanonyl acetate isolated from Chamaecyparis pisifera (1990)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 28 (1990), S. 1030-1034 
    Details
    ISSN: 0749-1581
    Keywords: 2D NMR ; Oplopanonyl acetate ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oplopanonyl acetate was isolated from Chamaecyparis pisifera. Its structure and stereochemical features were established using NMR techniques.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260281207
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  • 5
    Electronic Resource
    Electronic Resource
    Synthesis of α-Cyanoenamines by Cyanation of α-Bromoimmonium Bromides and Dehydrobromination of β-bromo-α-(dialkylamino)nitriles (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 3846-3857 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese von α-Cyanenaminen durch Cyanierung von α-Bromimmonium-bromiden und Dehydrobromierung von β-Brom-α-(dialkylamino)nitrilenDie Reaktion der α-Bromimmonium-bromide 4 mit Kaliumcyanid in Dimethylformamid gibt β-Brom-α-(dialkylamino)nitrile 5, die in verschiedenen Base-Lösungsmittel-Systemen zu (E)- und (Z)-α-Cyanenaminen 2 dehydrobromiert werden. Eine Modifizierung einer kürzlich veröffentlichten Synthese von α-Cyanenaminen 2 aus Aldehyden über Enamine führte zu einer verbesserten und schnellen Methode für die Darstellung der Titelverbindungen.
    Notes: The reaction of α-bromoimmonium bromides 4 with potassium cyanide in dimethylformamide gave rise to β-bromo-α-(dialkylamino)nitriles 5, which were dehydrobrominated in various basesolvent systems to afford (E)- and (Z)-α-cyanoenamines 2. An adaption of a previously published preparation of α-cyanoenamines starting from aldehydes via enamines led to an improved, efficient and fast synthesis of the title compounds.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831161208
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  • 6
    Electronic Resource
    Electronic Resource
    Facile Synthesis of 2-Alkoxy-2-aryloxiranes (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 3631-3636 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Eine einfache Darstellung von 2-Alkoxy-2-aryloxiranenTertiäre (α-Bromalkyl)arylketone 1 reagierten mit überschüssigem Kaliumcarbonat in trockenem Alkohol ausschließlich zu den entsprechenden 2-Alkoxy-2-aryloxiranen 4. Silbercarbonat in trockenem Alkohol führte in einer Konkurrenzreaktion zur Bildung von 4 und zu einer semibenzilischen Favorskii-Umlagerung (→5). Dagegen trat mit Silber-hexafluoroantimonat ausschließlich die letztere Umlagerungsreaktion ein.
    Notes: Tertiary α-bromoalkyl aryl ketones 1 were converted into 2-alkoxy-2-aryloxiranes 4 exclusively by reaction with excess potassium carbonate in the corresponding dry alcohol. Silver carbonate in a dry alcohol with these α-bromo ketones yielded competitively formation of 2-alkoxyoxiranes and semi-benzilic Favorskii rearrangement (→5), while silver hexafluoroantimonate in the same medium afforded the latter rearrangement reaction exclusively.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831161112
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  • 7
    Electronic Resource
    Electronic Resource
    Iminophosphorane-mediated synthesis of mesoionic 1,3,4-Oxadiazolo-[3,2-a]pyridinylium-2-aminides (1988)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 121 (1988), S. 1495-1500 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Iminophosphoran-vermittelte Syntheses von mesoionischen 1,3,4- Oxadiazolo[3,2a]pyridinylium-2-aminidenDas Iminophosphoran 2 reagiert mit Methylisocyanat zu dem mesoionischen 1,3,4-Oxadiazolo[3,2-a]pyridinylium-2-methylaminid 3, das durch CF3SO3CH3 zum 1,3,4-Oxadiazolo[3,2-a]-pyridinium-Kation 4 methyliert wird. Struktur 4 wurde durch Röntgenstrukturanalyse gesichert. Durch Einwirkung von Base lagert das mesoionische Aminid 3 zum isomeren mesoionischen 1,3,4-Triazolo[3,2-a]pyridinylium-2-olat 11 um. Verbindung 3 wird durch (Arylimino)triphenylphosphorane in die entsprechenden 1,3,4-Oxadiazolo[3,2-a]pyridinium-2-arylaminide 12 umgewandelt, die auch aus Iminophosphoran 2 und Hydroximoylchloriden zugänglich sind.
    Notes: Reaction of iminophosphorane 2 with methyl isocyanate yields the mesoionic 1,3,4-oxadiazolo[3,2-a]pyridinylium-2-methylamindie 3, which undergoes N-methylation with CF3SO3CH3 to give the 1,3,4-oxadiazolo[3,2-a]pyridinium cation 4. The structure of compound 4 has been established by means of X-ray crystallography. Mesoionic aminide 3 undergoes rearrangement by the action of base to give the isomeric mesoionic compound 1,3,4-triazolo[3,2-a]pyridinylium-2-olate 11. Compound 3 by the action of (arylimino)triphenylphosphoranes is converted into the corresponding 1,3,4-oxadiazolo[3,2-a]pyridinylium-2-arylaminides 12, which can be also prepared from iminophosphorane 2 and hydroximoyl chlorides.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19881210825
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  • 8
    Electronic Resource
    Electronic Resource
    Synthesis, Characterization and Dynamic Behavior of (π-Allyl)palladium Complexes with Polydentate Nitrogen Ligands, Evidence of a Dissociative Mechanism (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 589-594 
    Details
    ISSN: 0009-2940
    Keywords: Fluxionality ; Heterocyclic ligands ; Palladium complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New examples of the fluxional behavior of (η3-allyl)palla-dium complexes are described. Variable-temperature experiments and line-shape analysis of two (η3-allyl)palladium complexes containing 2-(1H-pyrazol-1-yl)azine ligands were performed in order to determine the activation free energies, enthalpies and entropies of the process. A dissociative mechanism pointing to a selective Pd-N cleavage is proposed on the basis of these results and NOE experiments above and below the coalescence temperature.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19961290519
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  • 9
    Electronic Resource
    Electronic Resource
    Determination of pipecolic acid in serum or plasma by solid-phase extraction and isotope dilution mass spectrometry (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 566-571 
    Details
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The determination of pipecolic acid in serum or plasma by positive chemical ionization gas chromatography/mass spectrometry is assessed. This quantitative method involves stable isotope dilution and cation-exchange solid-phase extraction. Several derivatives of pipecolic acid and its octadeuterated analogue were investigated for their mass spectrometric characteristics. The beptafluorobutyric methyl ester derivatives afford optimal resolution on gas chromatography of biological extracts. Moreover, the derivatizing reagent (methanolic HCl) allows a combined elution and derivatization. Selected ion monitoring is performed on the [M + H]+ ions of both analyte and internal standard, at m/z 340 and 348, respectively. Serum or plasma samples from healthy subjects and patients suspected of peroxisomal diseases have been examined.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200180810
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  • 10
    Electronic Resource
    Electronic Resource
    Gas chromatographic determination of residual ethylene oxide in gas-sterilized, medical-grade plastics (1984)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 7 (1984), S. 587-589 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography, GC ; Packed glass columns ; Solvent extraction ; Plastics ; Ethylene oxide ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240071011
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