Zur Polymorphie von Dapson und Ethambutoldihydrochlorid

Zusammenfassung Bei den Arzneistoffen Dapson und Ethambutoldihydrochlorid liegen außergewöhnlich komplizierte Polymorphieverhältnisse vor. In beiden Fällen wurden vier Modifikationen nachgewiesen, beiDapson existiert außerdem noch ein Hydrat. Das Dapson-Anhydrat liegt als enantiotrope Mod. III vor, die bei 80° in Mod. II übergeht. Diese Form ist meist bis zu ihrem Schmelzpunkt beständig. Mod. I, die aus der Schmelze kristallisiert, ist ebenfalls mit Mod. II enantiotrop. Außerdem besteht zwischen Mod. I und Mod. III Enantiotropie. Die Umwandlung Mod. IIIMod. II erfolgt spontan und unabhängig von Keimen, so daß der Schmelzpunkt von Mod. III nicht bestimmt werden kann. Bei Mod. IV konnte keine Enantiotropie mit einer anderen Kristallform nachgewiesen werden. Ethambutoldihydrochlorid weist nur enantiotrope Umwandlungen durch Umklappen ganzer Kristalle in das Gitter der anderen Modifikation auf, so daß nur der Schmelzpunkt der Hochtemperaturform bestimmbar ist. Die Tieftemperaturform besteht aus Mod. II, Mod. IV ist bei Raumtemperatur metastabil, während die instabile Mod. III nur ein ganz schmales Existenzgebiet zwischen ca. 40 und 45° besitzt, da sie sowohl mit Mod. IV als mit Mod. I enantiotrop ist.

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On the polymorphism of dapsone and ethambutol dihydrochloride

Summary There are extraordinarily complicated polymorphism conditions in the drugs dapsone and ethambutol chloride. In both cases, four modifications were detected, and in the case of dapsone there exists a hydrate in addition. The dapsone anhydrate is present as enantiotropic Mod. III, which transforms into Mod. II at 80°. This form is mostly stable up to its melting point. Mod. I, which crystallizes from the melt, is likewise enantiotropic with Mod. II. In addition, there is enantiotropy between Mod. I and Mod. III. The transformation of Mod. IIIMod. II takes place continuously and independently from nuclei, so that the melting point of Mod. III cannot be determined. In Mod. IV, no enantiotropy with another crystal form could be detected.Ethambutol dihydrochloride only displays enantiotropic transformations by folding over of entire crystals into the lattice of the other modification, so that only the melting point of the high temperature form can be determined. The low temperature form consists of Mod. II, Mod. IV is metastable at room temperature, whereas the unstable Mod. III only possesses a quite narrow range of existence between about 40 and 45°, since it is enantiotropic both with Mod. IV and with Mod. I.

     

On the γ-spectrum following225Ac α-decay

The decay of a²²⁵Ac source in equilibrium mixture with its decay products was investigated using high-resolution HP/Ge/ detectors. Energies and intensities of more than 78 -photons were measured with an improved accuracy; 44 of them are reported for the first time. A tentative²²¹Fr level scheme was built on the basis of good energy sum relationships; seven new²²¹Fr excited levels are proposed at 496.9, 570.9, 603.5, 630.7, 637.7, 649.0 and 758.9 keV.     

Polarographisches Verhalten von 1,2,3-Cyclohexantrion-trioxim in sauren Lösungen

The deoximation kinetics of 1,2,3-cyclohexanetrione trioxime was studied polarographically in 0.5 and 1.0M-HClO₄ solutions. From the three vicinal oxime groups, that in position 2 is hydrolysed by protonisation, followed by water uptake and hydroxylamine loss. The probable mechanism of the deoximation was proved by the study of the polarographic behaviour of 1,2,3-cyclohexanetrione-1,3-dioxime and by means of amperometric determination of the unchanged trioxime with Ni(II)-salt.     

First direct observation of the decay of neutral charmed particles produced by neutrinos in emulsion

Three examples of the production in emulsion by neutrinos and subsequent decay of neutral short-lived particles are reported. The flight times are ≈ 10^?13s, similar in order of magnitude to those previously determined for charged charmed particles in the same experiment.     

A search for charmed particles originating from the interactions of 300 GeV/c protons in emulsion nuclei

The associated production of charmed particles by the interactions of 300 GeV/c protons with complex nuclei has been sought using nuclear emulsions. The failure to observe any candidates for this process among some 60,000 interactions investigated implies, provided charmed particles lifetimes are in the range 10^?12 to 10^?14 s, a cross section for their associated production by the interactions of 300 GeV/c protons with nucleons of less than 1.5 microbarns at a 90% confidence level.