Browsing by Author "Okadia, Charles"

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    Bis(Trimethylenediamine) Cobait (III) Mediated Hydrolysis of Tripolyphosphate and Trimetaphosphate: Mechanistic Considerations
    (Addis Ababa Universty, 1991-07) Okadia, Charles; Tafesse, Fikru (PhD)
    The hydrolysis of tripolyphosphate ( pppi ) and trimetaphosphate (mpppi ) at 10'3 M concentration by [tn 2Co(OH)(0H2 )]^, (tn = trimethylenediamine), using Eu2 f /H+ quenching was investigated. The europium quenching was adopted since other methods interfere with phosphate analysis. The reactions were monitored by measurement of orthophosphate (pi ), pyrophosphate (ppi ), tripolyphosphate ( pppi ) and trimetaphosphate ( mpppi ) in the quenched aliquots of the reaction mixtures of the reagents. A method was developed to separate and determine the different phosphate species in the orthophos phate form using acetone- phosphomolybdate complex as the analytical reagent. The reactive species with regard to the hydrolysis were found to be a 3: 1 tn2Co( 111)ppp i and tn2Co( 111)mpppi complexes. The results showed larger amounts of hydrolytic products for the directly added systems than those of stepwise additions . The production of phosphites in the reaction solution that contain [tn2Co(OH )(0H 2)j* and tri metaphosphate was ob served . Spectrophotometric determination of the phosphite was done by first oxidising it with iodine to orthophosphate and using acetone-phospho molybdate complex as the analytical reagent . Factors affecting the formation and degradation of the reactive and unreactive species have been discussed and plausible mechanisns formulated .