Chelating agent, choice

In 1956 it was found that when pyridine is refluxed with a modified Raney-nickel catalyst, 2,2 -bipyridine (1) is formed in satisfactory yield. The isomeric bipyridines could not be detected, and the product was readily purified. Similar heterocyclic biaryls have been formed in the same way from substituted pyridines and from some related compounds, the yield being dependent on the nature of the compound. The reaction has become the method of choice for the preparation of 2,2 -bipyridine, and it is now used on an industrial scale. Bipyridyls are of particular importance as chelating agents. 

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. 

During oxide lead flotation, the choice of collector is rather limited to xanthates, which are used in operating plants. Dithiophosphates and mercaptans are used as secondary collectors. This is due to the fact that natural ores contain a variety of floatable gangues, for which the anionic flotation process is not applicable. The use of chelating agents as flotation collectors for oxide lead flotation have been extensively examined [5,6], Oximes/fuel oil... 

Analysis of inorganic complexes. Valuable information has been arrived at by proper choice of a chelating agent and confirmation of the structure of complexes has been arrived. 

As we have seen, the body has essentially no means of eliminating iron, so an excessive intake of iron causes various problems known as siderosis. Chelating agents are used to treat the excessive buildup of iron. In many cases (he chelates resemble or are identical to the analogous compounds used by bacteria to chelate iron. Thus desferrioxamine B is the drug of choice for African siderosis.1)7 The ideal chelating... 

This danger is minimal if calcium disodium EDTA is used as the chelating agent and it has now become the material of choice in cases of lead poisoning. Except in massive doses it is almost nontoxic and treatment with CaNa2EDTA results in a rapid depletion of lead in the soft tissues prolonged treatment is necessary for the removal of lead from bone72). 

The choice of the bioreactor type for denitrification of NO to N2 and the regeneration of the chelating agent Fe(II)EDTA2 is another important decision. A properly designed and controlled bioreactor should ensure high biomass concentration, constant temperature and pH, optimal mixing and correct shear conditions. Other important aspects are listed below ... 

Crosslinking catalyst Through choice of die appropriate metal (Ti or Zr) and chelating agent reactivity can be controlled Increased reaction rate in silicone, polyurethane, and epoxy systems... 

Five of the compounds shown below are good chelating agents and five are pdor. Decide which are good and which are poor and justify your choices. 

The Choice of a Chelating Agent for inactivating Trace Metals. Parti. A Survey of commercially available Chelating Agents. 

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