Chelating agents for

Selected Chelating Agents for the Fluorometric Analysis of Inorganic Metal Ions... 

The carbanions derived from acylthiophenes have been condensed with aldehydes,and, through the Claisen condensation with esters, thienylsubstituted -diketones have been obtained. 2-Thenoyl trifluoroacetone, first prepared by Reid and Calvin through the Claisen condensation of 2-acetylthiophene with ethyl trifluoracetate, has become an extremely useful chelating agent for the extraction of numerous elements from strongly acidic solutions, The tautomeric form which dominates in aqueous solution is the ketone hy-drate. Other thiophenes have also proved useful for analytical purposes. ... 

The choice of a satisfactory chelating agent for a particular separation should, of course, take all the above factors into account. The critical influence of pH on the solvent extraction of metal chelates is discussed in the following section. 

Neale, C.N., Bricka, R.M. and Chao, A.C., Evaluating acids and chelating agents for removing heavy metals from contaminated soils, Environ. Progr., 16, 274-280, 1997. 

Brechbiel, M.W., McMurry, T.J., and Gansow, O.A. (1993) A direct synthesis of a bifunctional chelating agent for radiolabeling proteins. Tetrahedron Lett. 34, 3691-3694. 

Meares, C.F. (1986) Chelating agents for the binding of metal ions to antibodies. Nucl. Med. Biol. 13, 311-318. 

Subramanian, R., and Meares, C.F. (1991) Bifunctional chelating agents for radiometal-labeled monoclonal antibodies. In Cancer Imaging with Radiolabeled Antibodies (D.M. Coldenberg, ed.), pp. 183-199. Kluwer, Boston, MA. 

Preparation of Highly Active Co/Si02 Catalyst with Chelating Agents for Fischer-Tropsch Synthesis Role of Chelating Agents... 

Fig. 10. Typical chelating agents for radionuclides having the ability for further derivatization with biomolecules for targeted delivery.

Use of immobilised chelating agents for sequestering trace metals from aqueous and saline media presents several significant advantages over chelation-solvent extraction approaches to this problem [193,194], With little sample manipulation, large preconcentration factors can generally be realised in relatively short times with low analytical blanks. 

Monien and Stangel [598] studied the performance of a number of alternative chelating agents for vanadium, and their effect on vanadium analysis, by atomic absorption spectrometry with volatilisation in a graphite furnace. Two promising compounds were evaluated in detail, namely 4-(2-pyridylazo) resorcinol in conjunction with tetraphenylarsonium chloride and tetramethylenedithiocar-bamate. These substances, dissolved in chloroform, were used for extraction... 

BAL is the standard treatment for poisoning by arsenic compounds and will alleviate some effects from exposure to arsenic vesicants. It may also decrease the severity of skin and eye lesions if applied topically within minutes after decontamination is complete (i.e., within 2-5 minutes postexposure). Additional chelating agents for the treatment of systemic arsenic toxicity include meso-2,3-dimercaptosuccinic acid (DMSA) and 2,3-dimercapto-l-propanesulfonic acid (DMPS). 

Acetylacetone (AcAc) is a chelating agent for many metals. 50 cm3 of an aqueous solution of M2+ (5 x 10 3 M) is equilibrated with 20 cm3 of ether containing an excess of AcAc. If 94% of M is extracted into the ether, calculate the value of the distribution ratio given that M2+ + 2AcAcr —> M (AcAc)2 is the only reaction. 

Reaction with chelating agents. Such reactions have been used primarily for partial dealumination of Y zeolites. In 1968, Kerr (8,21) reported the preparation of aluminum-deficient Y zeolites by extraction of aluminum from the framework with EDTA. Using this method, up to about 50 percent of the aluminum atoms was removed from the zeolite in the form of a water soluble chelate, without any appreciable loss in zeolite crystallinity. Later work (22) has shown that about 80 percent of framework aluminum can be removed with EDTA, while the zeolite maintains about 60 to 70 percent of its initial crystallinity. Beaumont and Barthomeuf (23-25) used acetylacetone and several amino-acid-derived chelating agents for the extraction of aluminum from Y zeolites. Dealumination of Y zeolites with tartaric acid has also been reported (26). A mechanism for the removal of framework aluminum by EDTA has been proposed by Kerr (8). It involves the hydrolysis of Si-O-Al bonds, similar to the scheme in Figure 1A, followed by formation of a soluble chelate between cationic, non-framework aluminum and EDTA. 

A very important ligand (or chelating agent) for titrimetric analysis is the ethylenediaminetetraacetate (EDTA) ligand. It is especially useful in reacting with calcium and magnesium ions in hard water such that water hardness can be determined. The next section is devoted to this subject. 

Yazdi, A. V. and Beekman, E. J. Mater. Res. 10 (1995) 530-537. Design of highly C02-soluble chelating agents for carbon dioxide extraction of heavy metals. 

Hydroxypyranones and hydroxypyridinones are promising candidates as chelating agents for the treatment of iron overload, since many are readily available, they form stable complexes with Fe, and some are permitted food additives. Hydroxypyridinones are to be preferred to hydroxypyranones as the former form the more stable complexes and are less readily metabolized. An extensive literature on synthetic iron chelators has been built up over the past 20 years -we can cite only a very small proportion here. In the 1980s it was established that hydroxypyridinones, usually in the form of... 

The treatment of metal poisoning is to administer a compound that binds the metal ion more strongly than does the group in the active centre of the enzyme. These compounds are known as chelating agents. For lead, the compound ethyl-enediaminetetraacetic acid (EDTA) is used. For mercury, dimercaptopropanol (dimercaprol) is used. 

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