Thermal decomposition of the pyridinium salt of 1,3-bis(trimethylsilyl)-2,4-dimercapto-2,4-dithioxo-1,3-diaza-2λ5, 4λ5-diphosphetidine

It was found that the first step of thermal decomposition of the pyridinium salt of 1,3-bis(trimethylsilyl)-2, 4-dimercapto-2,4-dithioxo-1,3-diaza-2⁵,4⁵-diphosphetidine (I) most probably involves breakdown to the acid form HS(S)P(NHSiMe₃)₂P(S)SH (II). The latter is very unstable and decomposes further, the end-product being a polymer (PNS)_x. In this work, the mechanism of this process is investigated.

---

Zusammenfassung Man fand, daß der erste Schritt der thermischen Zersetzung des Pyridiniumsalzes von 1,3-Bis(trimethylsilyl)-2,4-dimercapto-2,4-dithioxo-1,3-diaza-25,45-diphosphetidin (I) sehr wahrscheinlich einen Abbau zur Säureform HS(S)P(NHSiMe₃)₂P(S)SH (II) beinhaltet. Letztere ist sehr unbeständig und zersetzt sich, wobei als Endprodukt ein (PNS)_x-Polymer entsteht. In vorliegendem Manuskript wird der Mechanismus dieses Prozesses näher untersucht.

     

Extraction--spectrophotometric determination of oxalate in urine and blood serum

An extraction--spectrophotometric method is described for the determination of oxalate, based on the formation of a mixed ligand vanadium (V)--mandelohydroxamic acid--oxalate complex. The complex was extracted into a solution of trioctylmethylammonium chloride (Adogen 446) in toluene and the absorbance measured at 535 nm. The experimental variables and interferences in this determination were studied. The detection limit is 0.5 microgram ml-1 and the range of application is between 2 and 8 micrograms ml-1. The method was applied to the determination of oxalate in urine and blood serum.     

An investigation of some homo- and heterobinuclear complexes of copper(II) and nickel(II) with pyridine-2-aldoxime

The reactions between copper(II) or nickel(II) with thecis-pyridine-2-aldoxime complexes of the same metal ions have been investigated by spectrophotometric measurements. The homo and heterobinuclear chelates involved have been isolated as the chlorides and characterized by spectroscopic and thermoanalytical techniques. The first decomposition step is not dependent on the furnace atmosphere (N₂ or O₂) and is accompanied by a large exothermic effect (DSC curves in N₂). TG curves show that binuclear complexes are generally slightly less stable than the respective mononuclear complexes but, in the case of [Cu(NiL₂)Cl₂(H₂O)₂], the complexation of copper(II) gives rise a drastic decrease of its thermal stability.

---

Zusammenfassung Die Reaktionen zwischen Kupfer(II) und Nickel(II) mit den cis-Pyridin-2-aldoxim-Komplexen der gleichen Metallionen wurden spektrophotometrisch untersucht. Die homo- und heterobinuklearen Chelate wurden als Chloride isoliert und durch spektroskopische und thermoanalytische Methoden charakterisiert. Der erste Zersetzungsschritt ist unabhängig von der Ofenatmosphäre (N₂ oder O₂) und ist stark exotherm (s. DSC-Kurven in Abb. 1). Die TG-Kurven lassen erkennen, dass zweikernige Komplexe im allgemeinen etwas weniger stabil als die entsprechenden einkernigen Komplexe sind, im Falle von [Cu(NiL₂)Cl₂(H₂O)₂], aber die Anlagerung von Liganden an das Kupfer zu einer drastischen Verminderung der Stabilität führt.

---

- -2- . - , . ( ) , -, . , , , , [Cu(NiL₂)Cl₂(H₂O)₂], .

---

---

This work was carried out with financial support by MPI National Project.     

Is nitrate really an inert electrolyte? A brief review

It has been common practice to use sodium or potassium nitrate as a supposedly inert background electrolyte or for adjustment of ionic strength, but nitrate forms sufficiently stable complexes with many metals for its use to result in erroneous values for stability constants. This note surveys the effects.     

Diffuse-reflectance Fourier transform-infrared spectroscopic microanalysis of the flavonolignans

Diffuse-reflectance Fourier transform-infrared spectroscopic (DRIFT) microanalysis (10 g samples) of a selected series of flavonoids was studied, comparing to transmission FT-IR spectroscopic analysis of the same samples at the mg level. DRIFT was shown to be a useful, sample-saving and reliable IR technique for the structural analysis and compound identification of the mainSilybum genus 3-OH-flavonolignans (silybin, isosilybin, silydianin, silychristin and isosilychristin) and the dihydroflavonol taxifolin.     

Kováts' coefficients for predicting polarities in silicone stationary phases and their mixtures

Summary A correlation between the retention polarity and the Kováts' coefficient has been found for a number of commercial stationary phases used in gas chromatography. The correlation has been used to predict the polarity of a few mixed stationary phase columns prepared as binary mixtures of OV-101 with OV-25, DC-550 or Carbowax 20M, and also mixtures of OV-225 with SP-2340. A linear relationship was found between polarity and mixture composition. The temperature dependence of the Kováts' coefficient was investigated and found to increase linearly with temperature, the rate of increase depending on the polarity of the stationary phase, with greater increases for more polar stationary phases.     

Photochemical degradation of hyaluronic acid by singlet oxygen

Changes of the rheological properties of hyaluronic acid (sodium-magnesium salt) solutions after exposure to UV radiation indicate a vigorous decrease in their viscosity, but its still strong shear rate dependence. Whereas the presence of the singlet oxygen sensitizer (anthracene-1-sulphonic acid) brings about a loss of shear dependence; the studied solutions show newtonian behavior.     

Chromatic number of Hasse diagrams,eyebrows and dimension

We construct posets of dimension 2 with highly chromatic Hasse diagrams. This solves a previous problem by Nesetril and Trotter.     

Longitudinal acceptance computation for A 50 MeV race track microtron

The algorithm for analysing of longitudinal motion and for calculating phase trajectory in race track microtron (RTM) with small injection energy and small energy gain per turn is described. A longitudinal acceptance is calculated.We are indebted to E. A. Perelshtein and N. Ju. Kazarinov and A. Ju. Molodozhencev for stimulating advices. We thank M. Slodika for work with program coding.