The hydrolysis of some acidic metal cations in acetonitrile containing traces of  water

Acetonitrile is a solvent in which the halogen acids are highly associated. The strongly polarizing Al3+ and Ti4+ ions, when present in acetonitrile with comparable concentrations of water, form very stable hydroxy complexes. These two factors bring about the formation of halogen acids when the metal ions are dissolved in solvent containing halide ions. The results show (at least for aluminium) that it is the dissociation of water rather than of solvent molecules which is involved. Values obtained by polarography for the degrees of hydrolysis of Al3+ and Ti4+ in 25mM H2O and 0.1M tetrapropylammonium chloride were 0.82 and 0.18 respectively. In 0.1M perchlorate media the values for AlCl3 and TiCl4 were 0.45 and 0.40 respectively, indicating that the hydrolysis of Ti4+ is limited as a result of complexing by competing chloride ions. Potentiometric titrations, conductance measurements, and u.v. spectra (for TiCl4) support the polarographic results. No significant hydrolysis could be detected for Mg2+, So3+, Ga3+, and Sn4+ in halide solutions of acetonitrile.

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Potentiometric titration of metal ions in methanol

Canadian Journal of Chemistry ◽

10.1139/v03-035 ◽

2003 ◽

Vol 81 (6) ◽

pp. 495-504 ◽

Cited By ~ 28

Author(s):

Graham Gibson ◽

Alexei A Neverov ◽

R S Brown

Keyword(s):

Metal Ions ◽

Potentiometric Titration ◽

Metal Ion ◽

Potentiometric Titrations ◽

Solvent Molecules

The potentiometric titrations of nine lanthanideIII triflates, ZnII and CuII triflate, and the NiII, CoII, MgII, and TiIV perchlorates were obtained in methanol to determine the titration constants (defined as the sspH at which the [OCH3]/[Mx+]t ratios are 0.5 and 1.5) as well as the apparent sspKa values for deprotonation of the metal-bound solvent molecules. The titrations were performed under various conditions with and without added salts as electrolytes, and the variations in the titration constants are discussed. In selected cases (La3+, Zn2+) the titration profiles were analyzed using a complex fitting program to obtain information about the species present in solution.Key words: potentiometric titration, methanol, sspH, metal ion, lanthanides, apparent sspKa.

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Perchlorate and difluorophosphate coordination derivatives of manganese carbonyl

Australian Journal of Chemistry ◽

10.1071/ch9780267 ◽

1978 ◽

Vol 31 (2) ◽

pp. 267 ◽

Cited By ~ 37

Author(s):

FL Wimmer ◽

MR Snow

Keyword(s):

Mass Spectroscopy ◽

Room Temperature ◽

Halide Ions ◽

Substitution Reactions ◽

Decomposition Products ◽

Solvent Molecules ◽

Ion Yields ◽

Manganese Carbonyl ◽

Hydrolysis Of ◽

Derivatives Of

The complexes Mn(CO)5(OClO3) and Mn(CO)3L2(OClO3) (L = PPh3, P(OPh)3; L2 = bpy*) are formed by abstraction reactions with AgClO4 from the corresponding bromo complexes in dichloromethane. The perchlorato complexes have been characterized by i.r. and mass spectroscopy. They undergo facile substitution reactions in which the perchlorato group is replaced by halide ions (X- = Cl, Br, I), phosphines [PR3 (R = Ph, p- tolyl, m-tolyl), dpe, dpm]* or solvent molecules (MeCN, PhCN, MeOH, Me2CO, py*). Reaction with fluoride ion yields Mn(CO)3F3 plus other decomposition products. When Mn(CO)5X and Mn(CO)3L2X (X = Br) are made to react with AgPF6 in dichloromethane, hydrolysis of the PF6- ion occurs to yield the corresponding difluorophosphato complexes (X = PO2F2-), which have been characterized by i.r., 19F N.M.R. and mass spectroscopy. They are reasonably stable at low temperatures, but decompose at room temperature. The difluorophosphato group is more inert than perchlorato with the rate of substitution decreasing in the order CO ≈ PPh3 > bpy > P(OPh)3.

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Factors Influencing the Separation of Glu-Plasminogen Affinity Forms I and II by Affinity Chromatography

Thrombosis and Haemostasis ◽

10.1055/s-0038-1661211 ◽

1984 ◽

Vol 52 (03) ◽

pp. 347-349 ◽

Cited By ~ 6

Author(s):

Daan W Traas ◽

Bep Hoegee-de Nobel ◽

Willem Nieuwenhuizen

Keyword(s):

Affinity Chromatography ◽

Dissociation Constants ◽

Ionic Composition ◽

Chloride Ions ◽

Factors Influencing ◽

Two Factors ◽

Human Plasminogen

SummaryNative human plasminogen, the proenzyme of plasmin (E. C. 3.4.21.7) occurs in blood in two well defined forms, affinity forms I and II. In this paper, the feasibility of separating these forms of human native plasminogen by affinity chromatography, is shown to be dependent on two factors: 1) the ionic composition of the buffer containing the displacing agent: buffers of varying contents of sodium, Tris, phosphate and chloride ions were compared, and 2) the type of adsorbent. Two adsorbents were compared: Sepharose-lysine and Sepharose-bisoxirane-lysine. Only in the phosphate containing buffers, irrespective of the type of adsorbent, the affinity forms can be separated. The influence of the adsorbent can be accounted for by a large difference in dissociation constants of the complex between plasminogen and the immobilized lysine.

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Reactions of Metal Ions in Dilute Solution: RECALCULATION OF HYDROLYSIS OF IRON (III) DATA

American Water Works Association ◽

10.1002/j.1551-8833.1969.tb03736.x ◽

1969 ◽

Vol 61 (4) ◽

pp. 190-192 ◽

Cited By ~ 14

Author(s):

J. Edward Singley ◽

James H. Sullivan

Keyword(s):

Metal Ions ◽

Dilute Solution ◽

Hydrolysis Of

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Hydrolysis of 5′,5′-Tri- or Tetraphosphate-mRNA 5′-cap Analogs Promoted by Cu2+or Zn2+Metal Ions

Nucleosides Nucleotides & Nucleic Acids ◽

10.1080/15257770.2010.551722 ◽

2011 ◽

Vol 30 (2) ◽

pp. 135-148 ◽

Cited By ~ 1

Author(s):

Alicja Stachelska-Wierzchowska ◽

Zbigniew J. Wieczorek

Keyword(s):

Metal Ions ◽

Hydrolysis Of

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Hypochlorite and superoxide radicals can act synergistically to induce fragmentation of hyaluronan and chondroitin sulphates

Biochemical Journal ◽

10.1042/bj20040148 ◽

2004 ◽

Vol 381 (1) ◽

pp. 175-184 ◽

Cited By ~ 65

Author(s):

Martin D. REES ◽

Clare L. HAWKINS ◽

Michael J. DAVIES

Keyword(s):

Metal Ions ◽

Metal Ion ◽

Transition Metal Ions ◽

Chloride Ions ◽

Superoxide Radicals ◽

Thermal Source ◽

Site Specific ◽

Trace Metal Ions ◽

Electron Reduction ◽

Polymer Fragmentation

Activated phagocytes release the haem enzyme MPO (myeloperoxidase) and also generate superoxide radicals (O2•−), and hence H2O2, via an oxidative burst. Reaction of MPO with H2O2 in the presence of chloride ions generates HOCl (the physiological mixture of hypochlorous acid and its anion present at pH 7.4). Exposure of glycosaminoglycans to a MPO–H2O2–Cl− system or reagent HOCl generates long-lived chloramides [R-NCl-C(O)-R′] derived from the glycosamine N-acetyl functions. Decomposition of these species by transition metal ions gives polymer-derived amidyl (nitrogen-centred) radicals [R-N•-C(O)-R′], polymer-derived carbon-centred radicals and site-specific strand scission. In the present study, we have shown that exposure of glycosaminoglycan chloramides to O2•− also promotes chloramide decomposition and glycosaminoglycan fragmentation. These processes are inhibited by superoxide dismutase, metal ion chelators and the metal ion-binding protein BSA, consistent with chloramide decomposition and polymer fragmentation occurring via O2•−-dependent one-electron reduction, possibly catalysed by trace metal ions. Polymer fragmentation induced by O2•− [generated by the superoxide thermal source 1, di-(4-carboxybenzyl)hyponitrite] was demonstrated to be entirely chloramide dependent as no fragmentation occurred with the native polymers or when the chloramides were quenched by prior treatment with methionine. EPR spin-trapping experiments using 5,5-dimethyl1-pyrroline-N-oxide and 2-methyl-2-nitrosopropane have provided evidence for both O2•− and polymer-derived carbon-centred radicals as intermediates. The results obtained are consistent with a mechanism involving one-electron reduction of the chloramides to yield polymer-derived amidyl radicals, which subsequently undergo intramolecular hydrogen atom abstraction reactions to give carbon-centred radicals. The latter undergo fragmentation reactions in a site-specific manner. This synergistic damage to glycosaminoglycans induced by HOCl and O2•− may be of significance at sites of inflammation where both oxidants are generated concurrently.

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