Metal halide complexing agents

Grafting in the Presence of Metal Halide Complexing Agents... 

Nakashio et al. reported the use of lipophilic dialkyIdimethlylammonium bromides as surfactants in the formation of emulsion liquid membrane systems (22). The two long alkyl chains provided a good hydrophilicity-lipophilicity balance (HLB) to form a stable emulsion membrane. This finding led us to attempt the use of such quaternary ammonium salts in an emulsion liquid membrane system for which the ammonium salt functions not only as the emulsifying agent but also as the carrier for heavy metal halide complexes (Figure 5). 

The alkali metal halides, particularly NaCl and KCl, find extensive application in industry (pp. 71 and 73). The hydrides are frequently used as reducing agents, the product being a hydride or complex metal hydride depending on the conditions used, or the free element if the hydride is unstable. Illustrative examples using NaH are ... 

The observation that the metal carbene complex, (CO)5W = C(Ph)2 [22], catalyzed the polymerization of cyclic olefins to ring opened polymers containing the diphenylmethylene unit of the catalyst provided additional evidence that carbenes were involved in the catalytic cycle. The formation of the initiating metal carbenes in the classic systems that consist of transition metal halides and alkylating agents was proposed to involve metal alkylation followed by oc-hydrogen loss, Eq. (6). Methane and propene were detected in the early stages of these reactions [23]. 

Hirooka (29) has proposed that copolymerizations of this type be named "complex copolymerization. Russian workers (55) have suggested that polymerizations initiated by radical catalysts in the presence of a complexing agent be called "complex-radical processes. Both polymerizations are more appropriately considered as polymerizations through activated charge transfer complexes, in which the Lewis acid or metal halide catalyzes the formation of the complex, and free radicals may or may not be necessary to initiate the homopolymerization of the complex. 

The. applications of ion-exchange chromatography are exemplified by the selection shown in table 4.18. Among the most notable are the separation of lanthanides and actinides using a citrate, lactate or EDTA eluting agent the separation of many metals as halide complexes on anionic resins and the separation of amino-acids with citrate buffers. The use of pressurized systems for complex mixtures is likely to become more widespread in the future. 

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