Tetrazole Azasydnone (C2N7O2H) And Its Salts: High-Performing Zwitterionic Energetic Materials Containing A Unique Explosophore

This work reports the first compound containing both a tetrazole and an azasydnone ring, a unique energetic material. Several energetic salts of the tetrazole azasydnone were synthesized and characterized, leading to the creation of new secondary and primary explosives. Molecular structures are confirmed by ¹H and ¹³C NMR, IR spectroscopy, and X-ray crystallographic analysis. The high heats of formation, fast detonation velocities, and straight-forward synthesis of energetic azasydnones should capture the attention of future energetics research.     

Indachlorins: Nonplanar Indanone‐Annulated Chlorin Analogues with Panchromatic Absorption Spectra between 300 and 900 nm

Indaphyrins, pyrrole‐modified porphyrins containing a cleaved pyrrole β,β′‐bond and two annulated indanone moieties, possess unusually broadened and redshifted UV/Vis spectra because of their π‐expanded chromophores. The parent free base indaphyrin has been crystallographically characterized, highlighting its strongly ruffled conformation incorporating a helimeric twist. It was shown to be susceptible to regiospecific derivatizations at the opposite side of the ring‐cleaved pyrrole (dihydroxylation, followed by functional group transformations of the resulting diol functionality), generating indaphyrin‐based chlorin analogues, indachlorins, that incorporate a dihydroxypyrroline, pyrrolindione, oxazolone, or a morpholine moiety. Structural modifications resulted in further broadening and hyper‐ and bathochromic shifts of the optical spectra, some of which possess a nearly panchromatic absorption between 300 to well above 900 nm. The extents to which these modifications affect their solid‐state conformations were analyzed.     

InCl3 Promoted Synthesis of Pyrano[3,2‐h]quinolines via Microwave Irradiation

An efficient and economical method has been developed for the synthesis of pyrano[3,2‐h]quinolines via an indium trichloride‐catalyzed one‐pot three‐component reaction of 8‐hydroxyquinoline with aromatic aldehydes and malononitrile/ethyl cyanoacetate under microwave irradiation.     

Higher regularity of the free boundary in the parabolic Signorini problem

We show that the quotient of two caloric functions which vanish on a portion of an \(H^{k+ \alpha }\) regular slit is \(H^{k+ \alpha }\) at the slit, for \(k \ge 2\). In the case \(k=1\), we show that the quotient is in \(H^{1+\alpha }\) if the slit is assumed to be space-time \(C^{1, \alpha }\) regular. This can be thought of as a parabolic analogue of a recent important result in De Silva and Savin (Boundary Harnack estimates in slit domains and applications to thin free boundary problems, 2014), whose ideas inspired us. As an application, we show that the free boundary near a regular point of the parabolic thin obstacle problem studied in Danielli et al. (Optimal regularity and the free boundary in the parabolic Signorini problem. Mem. Am. Math. Soc., 2013) with zero obstacle is \(C^{\infty }\) regular in space and time.     

Zur Bestimmung der Verwölbungen und Profilverformungen von elastischen Stäben mit beliebigen und dünnwandigen Querschnitten

Übersicht Eine bereits vorgestellte Theorie, die eine schrittweise Bestimmung der Verwölbungen und Profilverformungen von Stäben mit beliebiger Querschnittsform ermöglicht, wird zusammengefaßt und hinsichtlich des Problems gekoppelter Biegung und Torsion erweitert. Dabei wird auf einer allgemeinen Approximationsstufe die Lage des Schub und Drillruhepunkts für das zugehörige Verwölbungsproblem angegeben und die Einführung von Hilfskräften zur Erzeugung von Gleichgewichtszuständen für das zugehörige Profilverformungsproblem erörtert. Die Theorie wird anschließend auf Stäbe mit dünnwandigen Querschnitten spezialisiert, Beispiele aus der Ingenieurpraxis sollen die Anwendbarkeit des Verfahrens zeigen.

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On the determination of cross-sectional warpings and distortions of bars with arbitrary and thin-walled cross-sections

Summary An already presented theory which allows for a stepwise determination of cross-sectional warpings and distortions of bars with arbitrary cross-sections is summarized and extended with respect to the problem of coupled bending and torsion. On a general approximation level the locations of the shear centers due to bending and torsion are given for the corresponding warping problem and the introduction of auxiliary forces in order to get equilibrated states of stress is discussed for the corresponding distortional problem. The theory is then specialized to bars with thin-walled cross-sections. Examples from the engineering practice shall demonstrate the applicability of the method.

     

Diosgenin aus Yams als Hormonvorstufe

Diosgenin as a sapogenin is the aglycone of the saponine dioscin. It is occuring in plants such as yam, from which it is isolated on industrial scale since the 1940ies. Plant diosgenin is a starting substance for the synthesis of human, i.e. animal, hormones and “the pill”, which as a hormonal contraception represents a revolution in the control of human sexuality. History, isolation and spectroscopy of this complex sapogenin are reported. This article extends the briskly discussed feature “50 years pill in Germany” (Streller & Roth, ChiuZ, 2011 [( 1 ) ]) by a particular compound example. It belongs to the series on isolation and spectroscopy of natural products in this journal.     

Eucalyptol aus Eukalyptusöl

Eucalyptol (1,8‐cineol), a cyclic monoterpenoid ether, is the dominant portion of eucalyptus oil, an essential oil of Eucalyptus globulus, accessible by steam distillation of its leaves. Some herbs and spices such as basil and cardamom also contain it as characterising flavour compound. Eucalyptus is a very diverse genus of Myrtaceae naturally occurring in Australia to whom the species have adapted in evolution. Planting Eucalyptus trees outside Australia has both benefits for poor populations and drawbacks. Especially, the enormous water consumption has been criticized. The total impact is doubtful. Eucalyptol is used in flavorings, fragrances, confectionery, cosmetics, cough suppressants, and insect repellents. Higher than normal doses are a hazard. A convenient isolation of eucalyptol from eucalyptus is reported. All analytical spectra were recorded and are reproduced and interpreted either in the main part or in the supporting information. The project is a follow up of the recent book “Classics in Spectroscopy” by S. Berger und D. Sicker (Wiley‐VCH 2009).     

Steviosid aus Süßkraut

The diterpene glycoside stevioside is the most abundant among a group of sweet steviol glycosides, present in sweetleaf (Stevia rebaudiana), which is naturally occurring in Paraguay. It has already been used by the Guarani Indians as a sweetener. Since 2011 such “steviosides” have an EU approval as sweeteners E 960. They taste ca. 250 times sweeter than sucrose. Meanwhile, they have got a significant recognition, not least due to their use in Coca Cola life®. We describe the isolation of stevioside and rebaudioside A from dried leaves of the sweetleaf plant. The complete set of spectra for stevioside is reported. Based on students' laboratory work this project is a follow up of the book “Classics in Spectroscopy” by S. Berger und D. Sicker (Wiley‐VCH 2009).