Organophosphoric acid

Nickel and Cobalt. Often present with copper in sulfuric acid leach Hquors are nickel [7440-02-0] and cobalt [7440-48-4]. Extraction using an organophosphoric acid such as D2EHPA at a moderate (3 to 4) pH can readily take out the nickel and cobalt together, leaving the copper in the aqueous phase, but the cobalt—nickel separation is more difficult (274). In the case of chloride leach Hquors, separation of cobalt from nickel is inherently simpler because cobalt, unlike nickel, has a strong tendency to form anionic chloro-complexes. Thus cobalt can be separated by amine extractants, provided the chloride content of the aqueous phase is carefully controUed. A successhil example of this approach is the Falcon-bridge process developed in Norway (274). 

Moreover organophosphoric acid esters have found application as insecticides (e.g. Parathion). Some derivatives are highly toxic to man (e.g. Sarin, Soman). The organophosphonates act as inhibitors of the enzyme cholinesterase by phosphorylating it. This enzyme is involved in the proper function of the parasympathetic nervous system. A concentration of 5 x 10 g/L in the air can already cause strong toxic effects to man. 

Zhu, T. A structure parameter characterizing the steric effect of organophosphorous acid extractants. International Solvent Extraction Conference, Cape Town, South Africa, Mar. 17-21, 2002, 203-207. 

The potential use of foams has also been demonstrated for the decontamination of nerve agents [80]. In these applications, the detoxification of the nerve agent was carried out by immobilizing the enzyme organophosphorous acid anhydrase within either a fire fighting or blast-containment foam carrier. 

Dichlorvos (9.50) is an insecticide of reportedly wide use, the metabolites of which in humans include dichloroethanol and dimethyl phosphate. Like paraoxon, dichlorvos is hydrolyzed by human serum. However, the enzyme activities hydrolyzing the two substrates were shown to differ by a number of criteria [114], Clearly large gaps remain in our understanding of the human metabolism of organophosphorus insecticides and other toxins. A bacterial phosphodiesterase appears as a promising tool to understand the catalytic mechanisms of organophosphoric acid triester detoxification [115-117],... 

Zirconium phosphonates are solid materials typically synthesized in amorphous forms under aqueous conditions by the reaction of a soluble salt of a tetravalent metal and a phosphonic acid or an organophosphoric acid ... 

Seifert J, Pewnim T. 1992. Alteration of mice L-tryptophan metabolism by the organophosphorous acid triester diazinon. Biochem Pharmacol 44(11) 2243-2250. 

Pyrophosphates may hydrolyze to inorganic phosphoric acid (phosphate) and an organophosphoric acid. 

The chemistry of the extraction of UO + by mixtures of organophosphoric acids and neutral organophosphorus compounds has been the subject of many studies, and the available information has been widely discussed.75 118 127 131 134 There is no general agreement on the mechanism of the synergistic effect, although an addition process such as... 

In the addition mechanism, the coordination number of uranium is increased from six to seven, whereas in the substitution mechanism, there is no increase in the coordination number. The absence of any synergistic effect for uranium(IV) and thorium(IV),127 which give coordination-saturated complexes M(HA2)4 with organophosphoric acids in which the metal ions are eight coordinate, is in accord with the addition mechanism. 

The degradation by gamma radiolysis of the mixed solvents DMDOHEMA-organophosphoric acid has been studied in the presence of acidic aqueous phase. Some G-values related to the disappearance of DMDOHEM A have been estimated ... 

Kislik V and Eyal A. Mechanisms of titanium(IV) and some other transition metals extraction by organophosphoric acids. In Logsdail DH and Slater Ml Eds. Proceedings of ISEC 93, London, July 1993. Elsevier Applied Science for SCI 1993 3 1353-1361. 

Kdtzsch, H.J., Seiler, C.D., and Vahlensieck, H.J., Eunctional group-containing organophosphoric acid esters as adhesive or coatings for metal, Dynamit Nobel A.-G., German Patent Appl. DE 2344197, 1975 Chem. Abstr, 83, 44864, 1975. 

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