Synthesen von Heterocyclen, 100. Mitt.: Zur Chemie der Spiro-1,3-oxazindione

Zusammenfassung Spirooxazindione, dargestellt aus hydroaromatischen Anilen und monosubstituierten Malonsäuren, erleiden beim Erhitzen auf 130–150° in Gegenwart von Phenylisocyanat eine thermische Spaltung in CO₂, Cyclanonanil und ein Ketencarbonsäureanilid, welch letzteres zu Derivaten des 4-Hydroxycarbostyrils ringschließt. Das 3-Benzyl-spiran1 reagiert mit einem Überschuß an Phenylisocyanat auch zur 5-Benzyl-5-carboxanilino-1,3-diphenyl-barbitursäure. Der Reaktionsmechanismus wird diskutiert.

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Spirooxazindiones, obtained from hydroaromatic aniles and monosubstituted malonic acids, are cleaved at 130–150° in the presence of phenylisocyanate yielding CO₂, cycloalkylideneaniline and ketene acid anilide. The latter reacts to derivatives of 4-hydroxycarbostyrile. The 3-benzyl-spirooxazindione1 reacts with an excess of phenylisocyanate to 5-benzyl-5-carboxanilino-1,3-diphenyl-barbituric acid. The mechanism of these reactions is discussed.

     

Zur Chemie und Strukturchemie der Phosphide und Polyphosphide. 35 [1]

Chemistry and Structural Chemistry of Phosphides and Polyphosphides. 35. Eu₃P₄, Sr₃P₄, and Ba₃P₄. Polyphosphides with P₄^6? Chains in a α-ThSi₂ Type Defect Structure Eu₃P₄, Sr₃P₄, and Ba₃P₄ are formed by direct synthesis from the respective elements and by thermal decomposition of the diphosphides. The black, brittle compounds are very sensitive to hydrolysis. According to single crystal studies, the compounds have the Sr₃As₄ structure (space group Fdd2) with P₄^6?-chains. It is shown, that this structure type is a defect α-ThSi₂ structure. The central P—P-bonds are essentially longer than the peripheral bonds (232 pm vs. 223 pm, respectively). The bond angles and torsion angles are influenced by the trigonal-prismatic arrangement of the metal atoms. Eu₃P₄ is paramagnetic with μ = 7.78 B. M. per Eu and orders ferromagnetically at 19 K. Sr₃P₄ and Ba₃P₄ substitute the former incorrect identified phosphides M₄P₅. — The lattice constants of the isotypic arsenides Eu₃As₄, Sr₃As₄, and Ba₃As₄ were redetermined.     

Electrolyte diodes with weak acids and bases. II. Numerical model calculations and experiments

This is the second part of our work dealing with electrolyte diodes with weak acids and bases. In the first part an approximative analytical solution was derived for the steady-state current-voltage characteristic (CVC) of a reverse-biased diode (a quasi-one-dimensional gel connecting an acidic and an alkaline reservoir), applying either strong or weak electrolytes. An approximative analytical solution is compared here with a numerical solution free of any approximations and with CVCs measured experimentally with both strong and weak electrolytes. It is shown that the deviations between the numerical and analytical solutions are mostly due to assumptions made for the fixed charge concentration profiles. The concept of optimal analytical solution is introduced which does not use such assumptions and applies only the quasielectroneutrality and quasiequilibrium approximations. It is proven that the slope of the CVC based on the optimum analytical solution can be calculated without the complicated derivation of that solution itself. The calculation of that slope is based on the fact that in the optimum analytical solution all currents are inversely proportional to the length if the boundary conditions are held constant and realizing that in the middle part of the gel the only mobile counterions of the fixed ionized groups are hydrogen ions. In the experimental part the apparatus and the preparation of the gel are described together with the CVCs measured with strong and weak electrolytes. From these CVCs the fixed ion concentration in the middle part of the gel can be determined. That fixed ion concentration is 1.96 x 10(-4)M measured with weak electrolytes and 3.48 x 10(-4)M measured with strong electrolytes. The deviation indicates that the strong base causes some hydrolysis of the gel. Finally, possible applications of weak acid-weak base diodes are discussed.     

Theoretical aspects of C metabolic flux analysis with sole quantification of carbon dioxide labeling

The potential of using sole respirometric CO2 labeling measurement for 13C metabolic flux analysis was investigated by metabolic simulations. For this purpose a model was created, considering all CO2 forming and consuming reactions in the central catabolic and anabolic pathways. To facilitate the interpretation of the simulation results, the underlying metabolic network was parameterized by physiologically meaningful flux parameters such as flux partitioning ratios at metabolic branch points and reaction reversibilities. For real case flux scenarios of the industrial amino acid producer Corynebacterium glutamicum and different commercially available (13)C-labeled tracer substrates, observability and output sensitivity towards key flux parameters was investigated. Metabolic net fluxes in the central metabolism, involving, e.g. glycolysis, pentose phosphate pathway, tricarboxylic acid cycle, anaplerotic carboxylation, and glyoxylate pathway were found to be determinable by the respirometric approach using a combination of [1-13C] and [6-13C] glucose in two parallel studies. The reversibilities of bidirectional reactions influence the isotopic labeling of CO2 only to a negligible degree. On one hand, they therefore cannot be determined. On the other hand, their precise values are not required for the quantification of net fluxes. Computer-aided optimal experimental design was carried out to predict the quality of the information from the respirometric tracer experiments and identify suitable tracer substrates. A combination of [1-13C] and [6-13C] glucose in two parallel studies was found to yield a similar quality of information as compared to an approach with mass spectrometric labeling analysis of secreted products. The quality of information can be further increased by additional studies with [1,2-13C2] or [1,6-13C2] glucose. Respirometric tracer studies with sole labeling analysis of CO2 are therefore promising for 13C metabolic flux analysis.     

Zur Struktur der metallreichen Borid-Phase bei V,Nb und Ta

Zusammenfassung Für das metallreiche Borid der ungefähren Zusammensetzung Me₂B in den Systemen: V–B, Nb–B und Ta–B werden Gitterkonstanten und ein Strukturvorschlag angegeben. Der Aufbau wird aus dem T 2-Gitter hergeleitet. Für eine Zusammensetzung Me₃B₂ ergibt sich Isotypie mit U₃Si₂. Bei Ersatz eines Bor-Paares durch 1 B-Atom würde die Phase bei Me₃B liegen.Mit 1 Abbildung     

Homogeneous and heterogeneous asymmetric reactions. Part 5. Diastereoselective and enantioselective hydrogenation of cyclic β-keto esters on modified Raney-nickel catalysts

The hydrogenations of methyl 2-oxoeyclopentanecarboxylate ( 1 ), ethyl 2-oxocyelohexanecarboxylate ( 3 ), and 2-methylcyclohexanone ( 5 ) on unmodified Raney-Ni catalyst lead predominately to the formation of the cis-hydroxy diastereoisomers of 2 , 4 , and 6 , respectively (Scheme 2). In the asymmetric hydrogenations on catalysts modified with chiral tartaric acid ((R, R )-C₄H₆O₆/Raney-Ni and (R, R)-C₄H₆O₆/NaBr/Raney-Ni), the predominance of the cis-isomer increases significantly. The hydrogenations of β-keto esters 1 and 3 proceed with an enantioselectivity of 10–15% on the modified catalysts, while the similar hydrogenation of 5 yields optically inactive 6 . The (1S,2R)-enantiomers of the cis-isomers of 2 and 4 are formed in larger quantity, whereas the (lR,2R)-enantiomers of the corresponding trans-isomers predominate (Scheme 1). The enantioselective formation of trans- 2 and trans- 4 can be interpreted mainly in terms of the asymmetric hydrogenation of cyclic β-keto esters through the keto form, while that of the corresponding cis-hydroxy esters proceeds through the enol form.     

Die Kristallstruktur des Lithium-enneagermanats Li4[Ge9O20]

The crystal structure of lithium enneagermanate, Li₄[Ge₉O₂₀], has been determined and refined by least-squares, using three-dimensional single-crystal data. The compounds crystallizes with monoclinic symmetry (a=12.43,b=8.00,c=7.49 Å, =91.0^o; C2–C₂ ³) building up a framework structure which exhibits some similarity with the structures of Li₂[Ge₄O₉] and Li₂[Ge₇O₁₅]. Out of the 18 Ge-atoms in the unit cell 14 are surrounded tetrahedrally by oxygen showing an average distance of 1.757 Å; the remaining 4 Ge-atoms are octahedrally coordinated with an average distance of 1.886 Å.

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Die Kristallstruktur des Lithium-enneagermanats Li₄[Ge₉O₂₀]

Zusammenfassung Die Kristallstruktur von Lithium-enneagermanat Li₄[Ge₉O₂₀] wird an Hand dreidimensionaler Einkristalldaten ermittelt und nach der Methode der kleinsten Quadrate verfeinert (R=0,083). Die monoklin kristallisierende Verbindung (a=12,43;b=8,00;c=7,49 Å; =91,0^o; C2–C₂ ³) besitzt eine Gerüstruktur, die einen ähnlichen Aufbau wie Li₂[Ge₄O₉] und Li₂[Ge₇O₁₅] zeigt. Von den 18 Ge-Atomen in der Elementarzelle liegen 14 in tetraedrischer Koordination mit einem mittleren Ge–O-Abstand von 1,757 Å vor; 4 Ge-Atome sind oktaedrisch umgeben, mit einem mittleren Ge–O-Abstand von 1, 1886 Å.

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Mit 3 Abbildungen

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Herrn Professor Dr.O. Hromatka zum 65. Geburtstag gewidmet.     

Über das Verhalten von Betainen gegenüber Phenylisocyanat

Zusammenfassung Pyridinbetain reagiert mit Phenylisocyanat unter Verlust von CO₂ und H₂ zum 2-Oxo-1,3-diphenyl-4-(1-pyridinio)-2,3-dihydro-imidazol-5-olat (1a), während sich Thetin mit dem genannten Reagens zum 2,4-Dioxo-1,3-diphenyl-5-(dimethylsulfonio)-1,2,3,4-tetrahydro-pyrimidin-6-olat (2a) umsetzt.

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Reaction of betaines with phenyl isocyanate (reactions with betaine, III)

(1-Pyridinio)acetate reacts with phenyl isocyanate under the loss of CO₂ and H₂ yielding 2-oxo-1.3-diphenyl-4-(1-pyridinio)-2.3-dihydro-imidazol-5-olate (1a). The reaction of thetine with phenyl isocyanate gives 2.4-dioxo-1.3-diphenyl-5-(dimethylsulfonio)-1.2.3.4-tetrahydro-pyrimidin-6-olate (2a).

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Auszugsweise vorgetragen anläßlich der Chemikertagung in Wien, September 1968.     

Über Diphosphate vom Typ Me(IV)P2O7

Zusammenfassung Einkristalle von GeP₂O₇ werden hergestellt und röntgenographiert. Die Elementarzelle erweist sich, entgegen einer früheren Annahme¹, als kubisch, jedoch mita=22,85₄Å, und entspricht somit der 27fachen Zelle von ZrP₂O₇ nach dem Strukturvorschlag vonG. R. Levi undG. Peyronel ². Auf Diffraktometeraufnahmen werden auch für die analogen Verbindungen mit Si, Sn, Pb, Ti, Zr, Hf, Th und U zusätzlich sehr schwache Reflexe nachgewiesen, welche durch die gegenüber der einfachen Zelle niedrigere Symmetrie hervorgerufen werden. Danach besitzen offensichtlich alle Verbindungen Me(IV)P₂O₇ die große Zelle; die in der Literatur angegebenen Werte für die Gitterkonstante beziehen sich daher auf die Unterzelle. Bei CeP₂O₇ lassen sich wegen ungenügender Homogenität und mäßig kristallimen Zustandes die Überstrukturlinien nicht beobachten. Die Zugehörigkeit zu den übrigen Vertretern (Isotypie) ist aber wahrscheinlich. Die vonL. M. Borlera undA. Burdese ³ für die Unterzelle von CeP₂O₇ und GeP₂O₇ angegebenen Gitterparameter können nicht bestätigt werden. Die 6er-Koordination von Silicium sowie die Winkelung der P-O-P-Bindung in der P₂O₇-Gruppe werden diskutiert. Die Existenz der Unterzelle in anderen Temperaturbereichen ist möglich.Mit 2 Abbildungen     

Chlorsulfonierung von Aromaten mittels Malonsäurediamid-N,N′-disulfochloriden

Zusammenfassung Die Malonsäurediamid-N,N-disulfochloride1–4 übertragen beim Erhitzen in Benzol oder Toluol die SO₂Cl-Gruppe auf den Aromaten, wobei das Diamiddisulfochlorid in gasförmige Bruchstücke zerfällt. Das Massenspektrum von Isopropylmalonsäurediamid-N,N-disulfochlorid (1) wird diskutiert.

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Chlorosulfonation of aromatic hydrocarbons by means of malondiamide disulfochlorides

Malonamide-N,N-disulfochlorides (1–4) transfer their SO₂Cl-group to aromatic solvents if heated to reflux. Under these conditions the malonamide-N,N-disulfochlorides are cleaved into gaseous fragments. The mass spectrum of isopropylmalonamide-N,N-disulfochloride (1) is discussed.