Dowex® ion exchanger resin

Dow Chemical Company, Dowex ion exchange resins product data sheet, http //www.dow.com/liquidseps/prod/ prd dowx.htm, 20 August 2006. 

Uracils and related pyrimidines undergo oxidative addition to the 5,6-double bond, and the reaction with a number of oxidants to form 5,6-epoxides and 5,6-diols was discussed in CHEC-II(1996) <1996CHEC-II(6)93>. Oxidative halogenation can also occur <1996SC3583, 1998NN1125>, as shown by the formation of 5-bromo-5,6-dihydro-6-methoxyuracil 100 from uracil 99 by treatment with a mixture of potassium bromate and potassium bromide in the presence of Dowex ion-exchange resin in methanol <1996SC3583>. 

T0209 Dow Chemical Company, DOWEX Ion Exchange Resins... 

Dow Chemical Company Dowex Ion Exchange Resins Abstract... 

Dowex ion exchange resins include a range of anion and cation resins for multibed demineralization, mixed-bed condensate polishing, as well as nuclear and other specialty applications. Most Dowex resins are based on styrene copolymerized with divinylbenzene (DVB). According to Dow, styrene/DVB structures are the preferred matrices for ion exchange resins because... 

Disodium succinate [150-90-3] M 162.1. Crystd twice from water. Freed from other metal ions by passage of an 0.1 M soln through a column of Dowex ion-exchange resin A-l, sodium form. 

Discussion In principle, acetals are cleaved by acid-catalyzed hydrolysis. In most cases aqueous acetic acid, aqueous trifluoracetic acid, dilute HC1 in THF or DOWEX 50W (H+) resin are used. Thus, treatment of 6 with DOWEX ion exchange resin in methanol rapidly furnishes the corresponding 1,2-diol without any further chromatographic purification steps. Generally, polymer supported reagents benefit from the ease of removal from the reaction mixture just by filtration of the insoluble resin. The resulting diol is acetylated by addition of acetic anhydride and pyridine. Final acetal exchange is achieved by acetic anhydride and catalytic amounts of concentrated sulfuric acid. A mixture (2 1) of anomers is obtained. 

Karadjova and coworkers [90] in a detailed and comprehensive investigation established a scheme for fractionation of wine components and Cu, Fe, and Zn determination in the different fractions. Like Fe, the other two metals may analogously exist in wines as free ions, as complexes with organic acids and as complexes with proteins, polyphenols and polysaccharides. The resin XAD-8 was used for the separation of wine polyphenols. Dowex ion exchange resins were used for the separation of cationic and anionic species of metals that were subsequently quantified off-line in Bulgarian and Macedonian wines by FAAS or ET-AAS (depending on their concentration levels). 

DOWEX Ion Exchange Resins and Adsorbents, Optipore L493 and V493, Product InFormation, 1998. 

M buffer. These structures have been assigned after comparison of their CD and NMR spectra to spectra of the corresponding nucleosides. For enzymic studies, these compounds may be purified further by passage over Dowex ion-exchange resin as described for [y- -Pj-a-fo UTP below. 

The oxysulfate (orthorhombic) and the oxysulfide (trigonal) of californium have been reported (see Table 11.5) [121]. These compounds can be prepared by thermally decomposing either Dowex ion-exchange resin beads containing Cf(iii) or hydrated Cf2(S04)3 the oxysulfide is obtained in vacuum or reducing (hydrogen-containing) atmospheres. The oxysulfate does not decompose to the sesquioxide when heated in air until the temperature exceeds 860°C. 

The Suzuki reaction has been appHed to the synthesis of a biarylcyclopep-tide through a resin-capture-release methodology [123]. This involved the capture of aryl boronic acids, containing a remote aryl hahde, on ammonium hydroxide-form Dowex ion exchange resin, followed by a releasing... 

Vaultier has developed a solid-phase synthesis of macroqfdic systems by intramolecular Suzuki-Miyaura aryl-aryl macrocydization of polymer ionically bound borates 87 obtained by trapping of the respective aryl boronic adds by an ammonium hydroxide form Dowex ion exchanger resin (D-OH), leading to macro-cydes of type 88 in 16-22% yield (Scheme 3.38) [57]. 

Fig. 3. The elution of tnpositive actinide and lanthanide ions. Dowex-50 ion-exchange resin was used with ammonium a-hydroxyisobutyrate as the eluant.

One important factor to consider in the preparation of the organic phase is the presence of inhibitors in the monomers. Some formulae call for the removal of inhibitors, primarily TCB, from the monomers. The TCB inhibitor forms highly colored complexes with metallic salts rendering the final product colored. Styrene has about 50 ppm of TCB. DVB, being more reactive, contains about 1000 ppm of TCB. There are several options for the removal of inhibitors. Columns packed with DOWEX MSA-1 or DOWEX 11 ion-exchange resins (Dow Chemical Company) can be used. White drierite or activated alumina also works well. 

Aromatization of 8-(cyano or ethoxycarbonyl)-2-oxo-2,3,4,4a,7,8-hexa-hydropyrido[l,2-A][l,2]oxazine-8-carbonitriles 12 by treatment with CS2CO3 resulted the formation of (2-pyridyl)propionic acids 13 (00OL4007). Application of other bases, e.g. DBU, NEt3, Dowex 1X8-400 ion-exchange resin afforded (2-pyridyl)propionic acids in irreproducible or considerably lower yields. 

Deoxy-D-ribo-hexono-l,4-lactone. To 286 mg. of 2-deoxy-D-ribo-hexose in 4 ml. of water is added 0.3 ml. of bromine. The solution is kept overnight at 37°C. and is then aerated to remove the excess bromine. Silver carbonate (1.5 grams) is added and the mixture is filtered. The clear filtrate is stirred with 5.4 grams of Dowex-50W X8 (H+) ion-exchange resin, decolorized, and filtered, and the filtrate is evaporated... 

Place 200 g of ion exchange resin Dowex 50W-X8, 100-200 mesh, hydrogen form into a 1-L beaker and add 600 ml of 1 M hydrochloric acid solution. Allow to stand for 24 h with occasional swirling. Decant off the liquid and filter off the resin using filter funnel and paper. Place the resin in a beaker and add 600 ml of distilled water. Stand for 24 h with occasional swirling. Decant off the liquid and repeat the washing procedure until the wash water is neutral to pH paper. 

Gardell, S. Separation on Dowex 50 Ion Exchange Resin of Glucosamine... 

Toteja RSD, Jangida BL, Sundaresan M, Venkataramani B (1997) Water sorption isotherms and cation hydration in dowex 50w and amberlyst-15 ion exchange resins. Langmuir 13 2980-2982... 

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