Chelates, preparation

Ferric ammonium citrate [1185-57-5]—A mixture of complex chelates prepared by the iateraction of ferric hydroxide with citric acid ia the presence of ammonia. The chelates occur ia brown and green forms, are dehquescent ia air, and are reducible by light. 

Hydroxy ketones also give primarily syn 1,3-diols when chelates prepared with BC13 are reduced with quaternary ammonium salts of BH4 or BH3CN-.88... 

Table 8. Extraction of 5 ppm copper from ammoniacal solution using supported chelating agents and supported chelators prepared by the corkscrew method as noted above. Modified from [26] Summary...

Adverse effects. Bismuth chelate, particularly as a liquid formulation, darkens the tongue, teeth and stool the effect is less likely with the tablet, which is thus more acceptable. There is little systemic absorption of bismuth from the chelated preparation, but bismuth is excreted by the kidney and it is prudent to avoid giving the drug to patients with impaired renal fimction. Urinary elimination continues for months after bismuth is discontinued. 

The simpler method for blood Pb required 200 pL from a whole blood sample drawn into a metal-free tube containing EDTA as an anticoagulant. This sample is mixed with internal standard and vortex mixed briefly. Then, with gentle vortex mixing, 400 pL of 4 m HNO3 are added dropwise. The sample is centrifuged at 1760 g for 10 min and the supernate transferred to a clean tube. The pH is adjusted to 7-9 with concentrated NH4OH. This solution is then ready for the chelate preparation step. 

The disposition of the endocyclic N-atom of the quinoline and azomethine rings determines the coordination. In azomethine bis-chelates prepared from 3-aminoquinoline, the azine nitrogen is not coordinated in... 

On the other side, a totally insoluble cross-linked Schiff-base complex was prepared as follows. The glycidyl ether of bisphenol A was reacted with a Schiff-base chelate (prepared from 2,4-dihydroxybenzaldehyde and 1,3-diaminopropane followed by metallation) in a molar ratio of, for example, 6 1 at 150-200 °C to obtain the polymer 4 as shown in Eq. 6-3 (see Experiment 6-1, Section 6.6) [19]. Polymeric copper complexes in particular exhibit good thermal stabilities and good mechanical properties such as tensile strength. 

The elemental analysis data of M-PTASH chelates, prepared by the mixing method, showed that the maximum capacity of the polymer occurs at a metal / polymer repeat unit concentration of 1 1 on molar basis. Moreover, these data indicate the absence of chlorine in the prepared chelates. IR spectra of these chelates were compared with the spectrum of the polymer itself in order to intcr[Hct the nature of chelation. Table II summarizes the IR stretching vibration absorption peaks of the investigated chelates. The IR spectra of various M-PTASH chelates... 

Although the chelates prepared by the soaking method showed variation of their IR spectra similar to that for those prepared by the mixing method (Ikble H), their element analyses were unsatisfactory to predict similar mixed chelate structure. The soaked chelates were generally found to contain smaller metal content relative to that of the mixed chelates. This indicates that successful chelating occurs readily at the polymer film surface but complete penetration of the metal cation into the core of the film is restricted. 

The synthesis of several metallized PTASH films via coordination of the polymer to various transition metal salts followed by a chemical reduction of the resulting chelates films is described. Coordination reaction was carried out either by the mixing or the soaking method. The metallized films showed novel functions due to characteristic properties of metal chelates. The incorporation of metals improved the tensile strength as well as thermal stability of the systems as evidenced by mechanical properties and TGA measurements This improvement could be clearly demonstrated in chelates prepared by the mixing method rather than those prepared by the soaking method. Metallization of the these films has been shown by SHM, X-my diffraction and ESCA measurements which indicated the presence of the metal adhered to the surface of the films Finally, potential advantages of these metallized films lie in their versatility with which their synthesis and processability can be accomplished as well as in their stability towards humid environment. 

The structure of a rhenium(V) complex with l,3,5-trideoxy-l,3,5-tris (2-hydroxybenzylamino)-c /i -inositol has been described, and the metal ion sequestering abilities of borate esters of 2-amino-2-deoxy-D-gluconate and 2-amino-2-deoxy-D-galactonate have been studied. The largest effects were measured upon adding Cd(ll) or Ni(II) to the borate - 2-amino-2-deoxy-D-gluconate system. A ribonucleoside technetium chelate prepared from 2, 3 -diamino-2, 3 -dideoxyadenosine is mentioned in Chapter 20. 

The early history of the rare earth elements is primarily dominated by the attempts to separate and purify the individual elements using the classical techniques of fractional crystallization and precipitation (Vickery, 1953). These procedures generally involved aqueous solutions which contained the hydrated ion and in this sense could be considered as the earliest examples of studies of the complexing properties of the rare earths. From a practical standpoint, however, the existence of the complexed ions was only incidental and was probably not even considered by the early workers. Early reference works of the 1920 s which summarize the extant information discuss only some double salts and adducts of the rare earths and do not consider them in terms of coordination compounds (Moeller, 1967). The first chelates prepared were probably the acetylacetonates used by Urbain (1896) in a separation procedure. 

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