Cation Exchange and Sorption Properties of TIN(IV) Phosphate

The ion exchange and sorption properties of crystalline Tin bis(monohydrogen orthophosphate) monohydrate of composition Sn(HPO(4))(2).H(2)O were studied in an aqueous solution of KCl over the temperature range 300-320 K, varying the pH and metal ion concentration in the solution. The data were explained on the basis of the law of chemical equilibrium. The metal ion sorption data were fitted to the Langmuir adsorption equation to evaluate the Langmuir parameters. The extent of adsorption was found to increase with an increase in temperature and metal ion concentration in the selectivity order Cu(2+)>Co(2+)>Ni(2+). The Langmuir parameters were used to calculate the thermodynamic functions like standard entropy, enthalpy, and free energy changes during the process of sorption. Copyright 2000 Academic Press.     

Studies on nessler's reagent and nessler's precipitate part II

The composition of the precipitate formed when the Nessler's reagent is treated with ammonia, is assumed as NH_n-1Hg₂I_n, aq. and has been studied potentiometrically from iodine-hypoiodite-system. It has been observed that the value of n depends on the concentrations of [HgI₄]^-2 and OH^- ions as well as on the amount of ammonia added and it may vary from 1 to 3. The colour of the precipitate deepens from brown to chocolate as the value of n increases.     

On periodic solutions of certain second order ordinary differential equations with periodic coefficients

Acta Mathematica Hungarica -     

Syntheses of the terpenoid precursors cyclopent-2-enone and cyclohex-2-enone diesters

Summary Two reaction pathways were elaborated for the practical and convenient synthesis of the title compounds. The first route applies a bromination-dehydrobromination sequence to introduce the double bond into 1-alkoxycarbonyl-2-oxocycloalkylacetic and propionic esters (4a–c,7a,b). The application of 2,6-lutidine for dehydrobromination of -bromocycloalkanones diesters (5a–c,8a,b) provides sufficient selectivity to carry out this step without affecting the sensitive ester group. Alternative pathways, involvingMichael reaction of diethyl 2-acetylsuccinate or -glutarate with acrolein and subsequent intramolecular aldol condensation, are presented in the case of cyclohex-2-enone derivatives2a,b.

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Zusammenfassung Für praktische und bequeme Synthesen der Titelverbindungen werden zwei Reaktionswege präsentiert. Der erste Weg basiert auf einer Bromierungs-Dehydrobromierungs-Sequenz zur Einführung der Doppelbindung in die 1-Alkoxykarbonyl-2-oxocycloalkylessig- und-propionsäureester (4a–c,7a,b). Die Anwendung von 2,6-Lutidin zur Dehydrobromierung der -Bromocycloalkanone-diester (5a–c,8a,b) sichert die ausreichende Selektivität, ohne die empfindlichen Estergruppen anzugreifen. Im Falle der Cyclohex-2-enon-Derivate (2a,b) zeigen wir einen alternativen Weg, der auf derMichael-Reaktion von Diethyl-2-acetyl-succinat bzw. -glutarat mit Acrolein basiert; die anschließende intramolekulare Aldol-Kondensation liefert die Zielprodukte.