(2-Vinyloxyethyl)hydrazines

Reaction of hydrazine hydrate with 2-chloroethyl vinyl ether afforded (2-vinyloxyethyl)hydrazine and 1,1-bis(2-vinyloxyethyl)hydrazine in 20-38% yield.     

Chemical studies on nitrogen heterocyclic skeleton of the Daphniphyllum alkaloids

From a biogenetic point of view, a great variety of related alkaloids isolated from the plant Daphniphyllaceae are related to one another by bond formation or fission. Thus, daphnialcohol acetate (6), a derivative of the degradation products of daphniphylline (1), was subjected to von Braun degradation followed by acid-catalyzed recyclization to give an isomer (8) of daphnialcohol, which has a new type of nitrogen heterocyclic skeleton. Furthermore, daphnilactone-B (3) was converted into a daphniphylline-type compound (19) via a plausible intermediate (21).     

The polarographic determination of indium in zinc-base alloys : The determination of indium in zinc and in zinc alloys of low aluminium content

Studies of the application of an 8-hydroxyquinoline extraction and of a zinc oxide “collection” procedure for the separation of trace amounts of indium from zinc alloys are described and discussed. A combination of radio-chemical and polarographic determination were employed for this work. A polarographic method for the determination of indium in zinc and in zinc alloys of low aluminium content is presented     

Konstitution von PrMn2—PrAl2

Zusammenfassung PrMn₂ (Th₆Mn₂₃-Struktur) löst etwa 0,5 Mol% PrAl₂. Eine C14-Struktur ist stabil von 2,25 bis 22,5 Mol% PrAl₂ und PrAl₂ (C15) löst 66,3 Mol% PrMn₂.

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Constitution of PrMn₂—PrAl₂

PrMn₂ (Th₆Mn₂₃ type) dissolves about 0.5 mole% PrAl₂. A C14 structure is stable from 2.25 to 22.5 mole% PrAl₂ and PrAl₂ (C15) dissolves 66.3 mole% PrMn₂.

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Herrn Prof. Dr.H. Nowotny gewidmet.     

Beitrag zur Sauerstoffbestimmung in Urancarbiden

Zusammenfassung Es wurden vergleichbare Versuche über die Bestimmung von Sauerstoff in Urancarbiden nach der Heißextraktionsmethode sowohl unter Vakuum als auch mit Hilfe des Trägergasverfahrens durchgeführt. Dabei zeigte es sich, daß für unsere Zwecke die Vakuumextraktion der Trägergasmethode überlegen ist. Von den untersuchten Badmetallen Eisen, Kobalt und Nickel lieferte das Kobalt bei Temperaturen von 1900 und 2000° C die besten Ergebnisse. Das Analysengut wurde in Stückchen in die Bäder gegeben. Die Verwendung von Pulvern erwies sich als ungünstig. Durch metallographische und autoradiographische Untersuchungen konnte dieses Verhalten u. a. durch Graphitausscheidungen in den Bädern erklärt werden. Thermodynamische Abschätzungen stimmten mit den Experimenten überein.

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Summary Comparable experiments on the analysis of oxygen impurities in uranium carbides by vacuum-fusion and inertgas-fusion methods have been performed, using various temperatures and bath compositions (iron, cobalt, and nickel). The latter fusion method proved to be unsatisfactory. Best results were obtained by the vacuum-fusion method, using a cobalt bath at 1900–2000° C. Thermodynamic evaluations were in good agreement with the experimental results. Metallographic and autoradiographic investigations explained that the unfavourable behaviour of powdered samples compared to massive samples was above all due to the increasing graphite precipitation in the bath.

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Fräulein U. Haarmann und Frau E. Popien danken wir für die tatkräftige Mithilfe bei der Durchführung der experimentellen Arbeiten.     

Determination of copper impurities in nickel and cobalt salts by atomic absorption spectroscopy

Summary A method is described for the rapid determination of traces of copper in the ppm range in cobalt and nickel salts. The % standard deviation for the analysis is reported as 3.4 to 3.7 for aequous solutions and 4.8 to 5.0 for carbon tetrachloride sprayed directly into the flame after extraction.

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Zusammenfassung Ein Verfahren zur raschen Bestimmung von Kupferspuren im ppm-Bereich in Kobalt- und Nickelsalzen wurde beschrieben. Die Standardabweichung in wäßrigen Lösungen beträgt 3,4 bis 3,7%, bei unmittelbarem Versprühen der Tetrachlorkohlenstoffextrakte in die Flamme 4,8 bis 5,0%.

     

Mass spectrometry in cardenolide chemistry—I

The mass spectrum of penta acetyl gitoxin is reported and discussed. This cardenolide derivative has recently been the subject of extensive metabolic study. Fragmentation processes are described which account for all of the major ions. High resolution measurements, metastable peaks and mass shifts, for the propionyl derivative, are reported to establish the validity of these proposals. A brief indication of the potential value of this technique, when combined with deuteroacetylation, to metabolic studies in this field is given, along with comments on the spectra of related compounds.     

High-throughput cytochrome P450 inhibition screening via cassette probe-dosing strategy. IV. Validation of a direct injection on-line guard cartridge extraction/tandem mass spectrometry method for simultaneous CYP3A4, 2D6 and 2E1 inhibition assessment

A highly efficient direct injection on-line guard cartridge extraction/tandem mass spectrometry (DI-GCE/MS/MS) method has been validated for high-throughput evaluation of cytochrome P450 (CYP) 3A4, 2D6 and 2E1 inhibition potential via cassette dosing of midazolam, dextromethorphan and chlorzoxazone using human hepatic microsomes and 96-well microtiter plates. Microsomal incubations were terminated with formic acid, centrifuged, and the resulting supernatants were injected for analysis by DI-GCE/MS/MS. Due to the novel use of an extremely short C(18) guard cartridge (4 mm in length), this method exhibits several advantages such as no sample preparation, excellent on-line extraction, short run time (2.5 min), and minimized source contamination and performance deterioration. The DI-GCE/MS/MS method demonstrates acceptable accuracy and precision for the simultaneous quantification of 1'-hydroxymidazolam, dextrorphan and 6-hydroxychlorzoxazone in microsomal incubations. The inhibition potential of CYP3A4, 2D6 and 2E1 has been evaluated using their known selective inhibitors. The IC(50) values measured by the cassette dosing approach (high-throughput) are consistent with those observed by an individual dosing regimen (conventional) and are all in good agreement with the literature values. The results suggest that the cassette probe-dosing strategy may provide an in vitro approach to minimize cost while maximizing throughput of CYP inhibition evaluation of new chemical entities in support of drug discovery and development.     

Yeast protein farnesyltransferase. Binding of S-alkyl peptides and related analogues

[reaction: see text] Protein farnesyltransferase (PFTase) catalyzes alkylation of cysteine residues by farnesyl diphosphate (FPP). The dissociation constants for the PFTase-peptide analogue complexes for the series of analogues fl-RTRC(X)VIA (X = H, methyl, dodecyl, farnesyl) were measured by fluorescence anisotropy. The results indicate that an ionizable sulfhydryl moiety is important for substrate binding and the farnesyl group in the product facilitates binding.