Quaternary anion exchange resins

Anion exchange resins of the quaternary ammonium hydroxide type (e.g., De-Acidlte FF, IRA-400 or Dowex I) are strong bases and are useful cataly s for the cyanoethylatlon of alcohols and possibly of other active hydrogen compounds. 

Anion exchange resins—gel type — Strongly basic- —quaternary ammonium functionality... 

Ion-exchange separations can also be made by the use of a polymer with exchangeable anions in this case, the lanthanide or actinide elements must be initially present as complex ions (11,12). The anion-exchange resins Dowex-1 (a copolymer of styrene and divinylben2ene with quaternary ammonium groups) and Amherlite IRA-400 (a quaternary ammonium polystyrene) have been used successfully. The order of elution is often the reverse of that from cationic-exchange resins. 

Strong"Base. Strong base anion-exchange resins have quaternary ammonium groups, - NR OH , where R is usually CH, as the functional exchange sites (see Quaternary ammonium compounds). These resins are used most frequentiy in the hydroxide form for acidity reduction. 

The most common catalysts in order of decreasing reactivity are haUdes of aluminum, boron, zinc, and kon (76). Alkali metals and thek alcoholates, amines, nitriles, and tetraalkylureas have been used (77—80). The largest commercial processes use a resin—catalyst system (81). Trichlorosilane refluxes in a bed of anion-exchange resin containing tertiary amino or quaternary ammonium groups. Contact time can be used to control disproportionation to dichlorosilane, monochlorosilane, or silane. 

Last time development of methods of iodine determination, which include preliminary sorption preconcentration of microcomponents and their subsequent determination in phase of concentrate get great practical significance. Silica gel (SG) with adsorptively modified quaternary ammonium salts (QAS) gets properties of anion-exchange resin. The sorbents modified in this way can be used successfully for determination of different anions. 

Equation (1) shows the simple conversion of a quaternary ammonium anion exchange resin from the chloride form to the cyanate form. Equation (2) shows the reaction of the resin in the cyanate form with hydroxylamine hydrochloride whereby hydroxyurea is formed and the anion Cl is retained by the quaternary resin. 

Strongly basic anion exchange resins, e.g. a cross-linked polystyrene containing quaternary ammonium groups, are largely ionised in both the hydroxide and the salt forms. Some of their typical reactions may be represented as ... 

Stirring of the methiodide with the anion exchange resin prior to introduction into the column is necessary, because of the insolubility of this quaternary salt in methanol. For methanol-soluble methiodides, a solution of the salt may be added directly to the methanol-washed resin column. 

Fujiwara, M., Matsushita, T., Kobayashi, T., Yamashoji, Y., and Tanaka, M., Preparation of an anion-exchange resin with quaternary phosphonium chloride and its adsorption behavior for noble metal ions, Anal. Chim. Acta, 274, 293, 1993. 

Anion exchange resins are also used frequently for the synthesis of specific quaternary ammonium salts [e.g. 29]. 

Commercial anion exchange resins have been used extensively for syntheses. A stoichiometric quantity of the anionic reactant is bound to the quaternary ammonium ion resin and allowed to react with an organic substrate in an organic solvent. The resin can be recovered and reused. Since the resins are not catalysts, they are not discussed further here. See other reviews for many examples l6,39,40 41 139). 

Polymer-bound reagent. Reaction of a quaternary ammonium anion-exchange resin (Amberlites) wth NaBH4 results in an immobilized borohydride reducing agent (1), which is somewhat less reactive than NaBH4.4... 

Consider a quaternary ammonium anion-exchange resin (R+) in its Cl form immersed in a solution of KC1. Let the concentration of an ion inside the resin be IX] and the concentration outside the resin be [X] . It can be shown from thermodynamics that the ion product inside the resin is approximately equal to the product outside the resin ... 

Duolite A-102, an anion exchange resin, has strong quaternary ammonium functional groups, with a capacity of 0.8 equivalent per liter. 

Separation of the Bitumen. The P. R. Spring bitumen was separated according to the flow diagram in Figure 1. Acidic compounds were isolated using a quaternary ammonium hydroxide anion exchange resin. Because the system is nonaqueous, ion exchange does not occur rather... 

POMs can he immobilized onto anion-exchange resins and surface-modified metal oxides with quaternary ammonium cation- or amino-functional groups via anion-exchange. Jacobs and coworkers tethered Venturello s catalyst [P04(W0(02)2)4]3-on a commercially available nitrate-form resin with alkylammonium cations and have carried out the epoxidation of allylic alcohols and terpenes with this supported catalyst [166, 167]. The regio- and diastereoselectivity of the parent homogeneous catalysts were preserved in the supported catalyst. For bulky alkenes, the reactivity of the POM catalyst was superior to that of Ti- 3 zeolite with a large pore size. The catalytic activity of the recycled catalyst was maintained completely after several cycles. 

Anion-exchange resins, particularly quaternary ammonium anion-exchange resins, are extensively applied to recover radionuclides from different process waste streams for instance, Pu(IV) and Th(IV) can be successfully recovered from uranyl ions using quaternary ammonium-based anionic resins in concentrated nitric acid [131-133],... 

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