Effect of K(+) on the Stoichiometry of Carbonated Hydroxyapatite Obtained by the Hydrolysis of Monetite

This study investigates the stoichiometry and the thermal stability of K(+)- and CO(3)(2)(-)-containing apatites (KCAp's) obtained by the hydrolysis of monetite. The analysis results of the samples after drying reveal that the KCAp's start to lose carbonate at temperatures V(Ca) + CO(3)(2)(-) + V(OH)] and [Ca(2+) + PO(4)(3)(-) <--> K(+) + CO(3)(2)(-)], where V(X) stands for a vacancy in the X-sublattice. Moreover, a small part of the CO(3)(2)(-) ions are presumably incorporated according to [Ca(2+) + 2PO(4)(3)(-) <--> V(Ca) + 2CO(3)(2)(-)]. A comparison of the contributions of these fundamental mechanisms with the results for precipitated Na(+)- and CO(3)(2)(-)-containing apatites shows that no intrinsic coupling whatsoever exists between these mechanisms.     

Chemoenzymatic Synthesis of Stannylated Metomidate as a Precursor for Electrophilic Radiohalogenations – Regioselective Alkylation of Methyl 1<Emphasis Type="Italic">H</Emphasis>-Imidazole-5-carboxylate [1]

Summary. Metomidate (ee 99%) substituted with iodine in the phenyl ring was prepared from (S)-1-(4-iodophenyl)ethanol (ee >98%) obtained by lipase-catalysed resolution and methyl 1H-imidazole- 5-carboxylate. The two fragments were joined highly regioselectively (alkylation only at N-1 of substituted imidazole) with inversion of configuration using the Mitsunobu reaction. Finally, p-iodometomidate was transformed into the p-trimethylstannyl derivative.     

Beiträge zur Chemie der Enaminoketone, 3. Mitt.: Darstellung und Eigenschaften neuer 3-Amino-1-phenylpropenone

Zusammenfassung Die Reaktion von 3-Dimethylamino-1-phenyl-propenon mit 2-Aminothiazol, 2-Aminopyridin, 3-Aminopyridin und 2-Aminopyrimidin verläuft unter Abspaltung von Dimethylamin zu den heterocyclisch substituierten Enaminoketonen3, 4, 5 und6. Diese Verbindungen liegen bei Raumtemperatur überwiegend in dercis-Form vor, nur im Thiazolylamino-tolyl-propenon (3) herrscht dietrans-Form vor.

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Enaminoketones, III.: Preparation and properties of some novel 3-amino-1-phenylpropenones

Reaction of 3-dimethylamino-1-phenyl-propenone with 2-aminothiazol, 2-aminopyridine, 3-aminopyridine and 2-aminopyrimidine, resp., proceeds with the elimination of dimethylamine to give the heterocyclic enaminoketones3, 4, 5, and6, resp. At room temperature thecis-form of these compounds predominates; only thiazolylaminotolylpropenone3 exists in thetrans-form.

     

Bestimmung von Perchlorethylen (PCE) in Tierk?rpermehlen mittels HPLC

Ohne Zusammenfassung

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Determination of perchlorethylene in carcasse meal by means of HPLC

     

New Peptide Lactones of the Streptogramin Family (Group B). Structures of Virginiamycin S5 and Viridogrisein II

Virginiamycin S₅ and viridogrisein II were isolated by liquid chromatography from the crude antibiotics virginiamycin and viridogrisein, respectively. Their structures were elucidated by amino-acid analysis and mass spectrometry.     

Spezielle analytische Methoden für die Arbeitsmedizin und Industriehygiene. IV

Zusammenfassung Eine vor kurzem publizierte Methode zur Bestimmung kleinster Mengen von Hexamethylendiisocyanat in Luft erwies sich im Konzentrationsbereich von 10^–2 ppm als zu wenig genau. Die Grundlagen dieser Methode wurden deshalb erneut untersucht. Mit Hilfe des verbesserten Verfahrens ist es möglich, Hexamethylendiisocyanat in Luft auch im Konzentrationsbereich von 10^–2 ppm und darunter sehr genau zu bestimmen. Mit demselben Verfahren können auch sehr stark verdünnte Lösungen von Hexamethylendiamin analysiert werden.

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Summary A recently published method for the determination of tiny amounts of hexamethylenediisocyanate in the air proved to be not accurate enough in the concentration area of 10^–2 ppm. Consequently the bases of this method were studied again. By means of the improved procedure it is possible to determine hexamethylenediisocyanate in air also in the concentration domain of 10^–2 ppm and below with high accuracy. Very highly diluted solutions of hexamethylenediamine can be analyzed likewise by means of this same method.

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III. Mitteilung⁶.