Metal ion complexing agents

Hydrolysis increases the terpolymer limiting viscosity number in water by a factor of up to 45. Other previously published data(66-68) show that these terpolymers are nonnewtonian viscosifiers, metal-ion complexing agents, and effective flocculators. These materials are still "small" molecules in aqueous solution, however, and do not function as effectively when used 1. as nonnewtonian viscosifiers or 2. drag reducing agents as do poly(l-amidoethylene-co-(sodium 1-carboxylatoethylene)) copolymers. 

S.No. Interfering Heavy Metal Ions Complexing Agent Remarks... 

A dramatic solvent effect in the thermolysis of tetramethyldioxetane, which followed the isokinetic relationship A/7 = /3A5 for a variety of solvents, formed the basis for the postulation of the concerted mechanism. However, it was shortly thereafter reported that the dramatic solvent effect in methanol was the result of catalysis by transition-metal ion impurities. In the presence of metal-ion complexing agents such as EDTA or Chelex 100, the menacing catalysis could be suppressed. That utmost care must be taken in measuring reliable kinetic parameters in 1,2-dioxetane decomposition cannot be overemphasized. 

Metallations of allyl sulfoxides have been achieved at -78 C with n-butyllithium in THP or more efficiently with LDA under similar conditions. - - Alkylations with primary alkyl iodides - - - and allylations with allyl - or phenyl bromides proceed in good yield, usually below -20 C and in less than 6 h. The reaction takes place predominantly at the a-site but there is often competition from y-alkylation leading to a-alkenyl sulfoxides (Scheme 98 Scheme 99). Changing the solvent, or introducing metal ion complexing agents, such as TMEDA were unsuccessful in changing the a y ratios observed in THF. 

In this technique, a polymerizable metal ion complexing agent in a hydrophobic solvent is sorbed by the polypropylene and polymerized with a free radical initiator in the membrane either with or without additional comonomers (19). Stability studies are carried out by determining the membrane s ability to transport Cu(II) from pH 4.2 sulfate/bisulfate buffer solutions over a number of weeks (20). The concept is illustrated in Figure 2. 

A. Warshawsky and A. Patchornik, Impregnated resins Metal ion complexing agent.s incorporated physically in polvmcric matrices, Israel J. Chem.. 17 (I97X). 307. 

This interpretation is in agreement with the solvent effect that is evident for the 5-decyl system data in Table 5.15. The extent of syn elimination is much higher in the nondissociating solvent benzene than in DMSO. The ion pair interpretation is also supported by the fact that addition of specific metal ion-complexing agents (crown... 

This compound is the most widely-used of the family of aminopolycarboxylic acids, which act as strong metal ion-complexing agents. Its near-ubiquity in surface waters has begun to cause concern. OH-induced degradation represents one way to cope with this problem. Radiolytic studies focusing on the action of OH have been undertaken recently [54, 55]. 

The geometry of the interactions of metal ions with selected side-chain groups found in proteins will now be considered this provides a promising avenue for the design of supramolecular metal ion-complexing agents. 

By comparing the residence times an image of the selectivity of the surface for the electrolyte components can be developed. The deposition of an alloy of two similarly sized components A and B has been chosen as an example. By a suitable selection of the experimental parameters (concentration of metal ions, complexing agents, potential, etc.), the deposition rates of A and B can be made equal and equivalent to the equal partial current densities = ig. Therefore one can distinguish between three cases. 

Source of calcium ions Source of zinc ions Source of metal ions Complexing agent... 

Separation, concentration, and recovery of both valued and toxic metal ions are becoming increasingly important due to dwindling mineral resources and the need to protect the environment, respectively (/,2). Therefore the development of efficient and selective metal ion complexing agents which may be utilized in such operations is of great interest. In this paper, we describe the preparation of several types of acyclic amide ligands and their evaluation in heavy metal ion separations. 

Because metal ions bind to and modify the reactivity and structure of enzymes and substrates, a wide spectrum of techniques has been developed to examine the nature of metal ions which serve as templates, redox-active cofactors, Lewis acids/bases, ion-complexing agents, etc. 

The pH at which metal ions are extracted depends on the distribution coefficient for the particular metal and complexing agent. As a result, the pH at which the metal ions are extracted varies, as shown by the results in Figure 11.10. This behavior allows one metal to be separated from another. For example, consider the separation of copper and iron with LIX 64N. As Figure 11.10 shows, LIX 64N extracts copper at pH 1.5-2.0, but iron is not extracted until above pH 2.5. The separations obtained when 0.2 % solutions of copper and iron are tested with a LIX 64N membrane at various pHs are shown in Figure 11.11. The copper flux is approximately 100 times higher than the iron flux at a feed pH of 2.5. 

---