Thiocyanate-assisted demetallation of α,β,γ,δ-tetra(p-sulfophenyl)porphinatoindium(III) in aqueous media

The rate law for the demetallation of the title indium(III)-porphin complex in aqueous acidic thiocyanate media at 3.00M ionic strength was found to be of the form where [H₄P^2?] is the concentration of the diacid product formed, [InP]_t is the total concentration of all forms of indium(III)-porphin complex present, and a and b are constants. The constant a is a pseudo-third-order rate constant with the value (0.057 ± 0.005)M^?2 s^?1 and b has the value 0.704M^?2 at 50.5°C. If the mechanism for demetallation involves ringpuckering with the attachment of two H⁺ ions, then 1/b can be identified with the product K₁K₂ for the stepwise dissociation of two protons from two ring pyrrolic nitrogen atoms of H₂InP^?. In the sulfonated tetraphenylporphin used for these studies the ring pyrrolic nitrogen atoms seem to be the most probable sites for protonation. If this identification is correct, the value of 1.42 ± 0.13 found for the product K₁K₂ shows the enormous effect that the presence of the In³⁺ center has on the ionization constants of these two protons. That the kinetic studies show saturation effects with respect to proton addition to InP^3? may result from the fact that In³⁺ sits about 0.6 Å above the porphin ring.     

Ein verallgemeinerter Kettenbruch-Algorithmus zur rationalen Hermite-Interpolation

Summary In this paper we consider rational interpolation for an Hermite Problem, i.e. prescribed values of functionf and its derivatives. The algorithm presented here computes a solutionp/q of the linearized equationsp–fq=0 in form of a generalized continued fraction. Numeratorp and denominatorq of the solution attain minimal degree compatible with the linearized problem. The main advantage of this algorithm lies in the fact that accidental zeros of denominator calculated during the algorithm cannot lead to an unexpected stop of the algorithm. Unattainable points are characterized.

Herrn Prof. Dr. Dr. h.c.mult. L. Collatz zum 70. Geburtstag gewidmet     

Vollautomatische titrimetrische Einzelanalyse in der Praxis

Zusammenfassung Voraussetzungen einer effektiven Automation der individuellen titrimetrischen Analyse werden dargestellt. Ein nach diesen Gesichtspunkten entwickeltes Gerät wird beschrieben und seine Anwendung in den Gebieten der Farbstoffe, Agrochemikalien, Additiven und Pharmaka aufgezeigt.

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Fully automated titrimetric individual analysis in practice

Summary Criteria for effective automation of individual titrimetric analyses are presented. Based on these, an automatic titration system has been developed which is described. Its performance and its applicability in the field of dyestuffs, agrochemicals, additives and pharmaceuticals has been investigated.