Solvating reagent

Finally, Is the solvating reagent Is added In the vapor phase to the freeze dried polymer, It Is possible to prevent the coupling reaction completely. We think that the THF molecules are preferentially located around the living ends and this hindrance prevents the coupling when the macroradicals are formed. 

Similarly uranyl nitrate is moved across a circuit by stripping a solvating reagent,... 

It should also be taken into account that a lot of synthetic processes in coordination chemistry are carried out in solvating media. So, the reaction schemes (1.1)—(1.8) should include solvating reagents and consider the possibility of formation of adducts of final complexes with solvent molecules [Scheme (1.9)] ... 

Chiral P-Hydroxy-a-Aminophosphonic Acids. An enan-tioselective synthesis of substituted dihydrooxazolin-4-yl phos-phonates was reported by the reaction of an aldehyde with a-isocyanomethylphosphonate ester catalyzed by (i )-(5)-(l) (eq 12). The enantiomeric purity of the product was determined by P H NMR spectroscopy using the chiral solvating reagent (.S)-(+)-2,2,2-trifluoro-l-(9-anthryl)ethanol. Independently, an asymmetric synthesis of ot-aminophosphonic acids was reported using the chiral ferrocenylamine catalyst (R)-(S)-(3) (eq 13). ... 

The reaction seen in Eqs. 242-244 are controlled by polar effects. A reaction-kinetics investigation on l-phenyl-2,3-epoxypropane has revealed that the reaction with organomagnesium compounds proceeds in two steps. The first, fast step is a process between the oxirane and the solvated reagent, leading to an equilibrium. 

Figure 3.8 Estimation of the enantiomeric purities of the enantiomers of JH III by using a chiral solvating reagent in1H NMR measurements (400 MHz, CDCb). Modified by permission of Shokabo Publishing Co., Ltd...

In aqueous effluents with high concentration of hydrochloric acid, different iron and zinc chlorocomplex species have been reported in the open literature. Fe + and Fe form only cationic or neutral compounds such as FeCF and FeCl2 and FeCF" and FeCla, while Zn + in the presence of chloride usually forms anionic chlorocomplexes that are selectively extracted with the solvating reagents typically employed in the extraction of anionic compounds. ... 

Solvating reagents such as neutral compounds (e.g., ethers, ketones, alcohols, and esters of carboxylic acids, alkyl phosphates, phosphonates, phos-phinates, phosphine oxides, and phosphine sulfides) and also esters of pyridinecarboxylic acids and certain benzimidazole derivatives that have electron-withdrawing substituents form solvates with extracted neutral species. For example, dialkylpyridine-3,5-carboxylates extract Cu(II) at pH 3 from concentrated chloride solutions ... 

Solvating reagents can also extract charged species together with counterion(s). For example, tributyl... 

Solvating reagents can also extract bulky anions, e.g., Cr04, Mo04, and anionic chlorocomplexes, by means of the hydration mechanism. For example. 

The preprotonation of solvating reagents, sucj alcohols, and the extraction of anionic species also possible ... 

The solvating reagents are usually less selective than acidic extractants and the transferred complexes are not as well defined. A high concentration of salts and/or the presence of complexing anions are needed to obtain the efficient extraction of metal species. The drawbacks are coextraction of acids and water. The back-extraction is usually carried out with water. 

Another possibility to extract a metal ion is to replace its hydrate water by a solvating reagent. This makes the metal species less hydrophilic and it can be transferred to an organic phase. The solvating reagent can be the organic phase or it can be dissolved in a diluent. A well-known example is the extraction of uranium by tri-n-butyl phosphate from nitric acid ... 

This effective concentration is determined by the degree of solvation of the cross-linked macromolecule in the liquid reaction mixture and by the time for diffusion of reactants into this inner volume of the polymer. Since in particles cross-linked to < 1% (100-400 mesh) diffusion requires about 1—2 minutes, this parameter might be neglected when judging possible conversions on the gel phase, whereas it is essential to know the swelling factor of the polymer in the specific mixture of solvent and reactants. From this point of view, in the example of chloromethylation in n-hexane, the state of reaction of the polymer cannot be described exactly, since the small amount of solvating reagent just may suffice to transform outer parts of the coiled macromolecule into the reactive state. 

The reagent Acorga CLX-50 was a novel introduction about 10 years ago based on a pyridine dicarboxylic ester. This behaved as a solvating reagent and recovered copper from chloride media as the complex CUL2CI2 but has only been used on a pilot scale. 

Since the AuCl4 anion is the most readily extracted of all the precious metal species, it is important that it is removed first from the leach liquor so that it does not contaminate the downstream products. Gold can be selectively removed from solution using a weakly solvating reagent. Extractants include ketones, alcohols, TBP, and amines (Amer 1983a Mooiman 1983). 

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