Anion exchange resins Amberlite

In order to obtain paromomycin In free base form, the hydrochloride is dissolved in water as a 3% solution, the solution Is poured into an adsorption column containing an anion exchange resin (Amberlite IR-45 or preferably IRA-411 or IRA-400) in the hydroxyl form and the column is washed with a small amount of water. 

Iron Conversion to bathophenanthroline complex adsorption om anion exchange resin (Amberlite A27) Densitometric scanning of resin at 550 nm [350]... 

When an anion exchange resin Amberlite IRA 400 [CN-] is used as a cyanating agent, the final products of the aldonitrone cyanating reaction are a-iminonitriles (Scheme 2.173) (Table 2.14) (634). 

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... 

Cyanohydrins are readily racemized with base, and this has been exploited by Oda and co-workers in a dynamic kinetic resolution of these substrates[10, n. In a typical procedure (Fig. 9-4), the cyanohydrins were formed by transhydrocyanation with acetone cyanohydrin, catalyzed by the hydroxide form of an anion exchange resin (Amberlite IRA-904). The reversible nature of the cyanohydrin formation allows racemization to proceed during the course of the enzyme-catalyzed acetylation, and the choice of isopropenyl acetate as the acyl donor means that the only by-product is acetone. 

Aldehydes may be dimerized, either to p-hydroxy aldehydes or to a,P-unsaturated aldehydes, by the use of the anion-exchange resins Amberlite and Dowex. ... 

Figure 5.11 Equilibrium distribution of UOj between anion-exchange resin Amberlite IRA-400 and aqueous solution containing 5 g HjSOg/liter and enough MgS04 to bring total SO4 " to 30 g/liter.

In this case the base used was the anion-exchange resin Amberlite IRA-400. 

Another recyclable chlorinating reagent, 3-(dichloroiodo)benzoic acid (60), can be conveniently prepared by the chlorination of commercially available 3-iodobenzoic acid (59). A reduced form of reagent 60, 3-iodobenzoic acid (59), can also be easily separated as a solid from the products of chlorination by basic aqueous work-up followed by acidification with HCl [68,69]. Scheme 5.24 shows an example of a chlorination cycle using reagent 60 [69]. Alternatively, 59 can be separated from the reaction products by treatment with anionic exchange resin Amberlite IRA 900 (Section 5.3.2). 

Iodosylbenzoic acid (85) is also a convenient recyclable hypervalent iodine oxidant for the synthesis of a-iodo ketones by oxidative iodination of ketones [88], Various ketones and p-dicarbonyl compounds can be iodinated by this reagent system under mild conditions to afford the respective a-iodo substituted carbonyl compounds in excellent yields. The final products of iodination are conveniently separated from by-products by simple treatment with anionic exchange resin Amberlite IRA 900 HCOs" and are isolated with good purity after evaporation of the solvent. The reduced form of the hypervalent iodine oxidant, 3-iodobenzoic acid (59), can be recovered in 91-95% yield from the Amberlite resin by treatment with aqueous hydrochloric acid followed by extraction with ethyl acetate [88]. 

A quaternary ammonium hydroxide type of anion exchange resin, Amberlite IRA-400 (OH ), is an effective catalyst for the alkylation of ethyl malonate, ethyl cyanoacetate, or cyanoacetamide with various alkyl halides.— E Molar equivalents of 2-ethylcyanoacetamide and allyl bromide stirred 2 hrs. at room temp, with Amberlite IRA-400 (OH ) in ethanol-water 2-allyl-2-ethylcyano-acetamide. Y 82%. F. e. s. K. Shimo and S. Wakamatsu, J. Org. Ghem. 28, 504 (1963). 

As membrane material for their direct ammonia-oxygen fuel cells, Lan and Tao used a blend of the anion-exchange resin Amberlite IRA 400 (hydroxide form) and poly(vinyl alcohol). As cathode material, Mn02 deposited on carbon materials was used. In different cell versions the anodes were prepared from Pt-Ru-C and from chrom-decorated nanosized nickel (size about 6 nm). Experiments with such cells at room temperature showed maximal power densities in the range 12 to 16 mW/cm. In some cases the power densities for ammonia-fed cells were higher than those for hydrogen-fed cells. The authors note that the development of direct ammonia fuel cells with alkaline membranes and inexpensive catalysts is still at an early stage. 

The more positive potential ( + 1.20 V vs Ag/AgCl) required for oxidation of Hg(dtc)2 precluded its determination using in situ formation unless a suppressor column was employed. The function of the suppressor column, which was packed with a commercially available anion exchange resin (Amberlite CG-400), is to remove excess dithiocarbamate ligand after separation but prior to detection. The suppressor column performed this operation very successfully and a sensitive, reproducible (over a period of 25 injections) Hg(dtc>2 response was observed. 

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