Ion exchange resin Dowex

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. 

The resulting product was dissolved in water and this solution was eluted through a strongly acidic ion-exchange resin (Dowex SOW). Lyophilization of the fractions provided the products cyanomethylsulfinylacetamide (70 mg, 51%) and cyanomethyl-sulfinylacetic acid (2S mg, 20%). 

In the method proposed by van Staden for the determination of three halides, these are separated in a short colunm packed with a strongly basic ion-exchange resin (Dowex i-X8) that is placed in an FI manifold. A laboratory-made tubular silver/silver halide ion-selective electrode is used as a potentiometric sensor. Van Staden compared the response capabilities of the halide-selective electrodes to a wide concentration range (20-5000 pg/mL) of individual and mixed halide solutions in the presence and absence of the ion-exchange column. By careful selection of appropriate concentrations of the potassixun nitrate carrier/eluent stream to satisfy the requirements of both the ion-exchange column and the halide-selective electrode, he succeeded in separating and determining chloride, bromide and iodide in mixed halide solutions with a detection limit of 5 /xg/mL [130]. 

HCl (6 M 1.5 mL) was added to a solution of oxazoline (500 mg, 1.48 mmol) in ethanol (1.5 mL), and the mixture heated at reflux for 24 h. After the solvent was removed in vacuo, the residue was purified by column chromatography (15% aqueous NH4OH) through an ion-exchange resin (Dowex 50WX8-100) to give (S)-(+)-a-benzyl serine as a white solid (365 mg, 98%). 

The methodology for the conversion of epoxyphosphonates into allylic alcohols has been used in the preparation of diethyl 2-formylvinylphosphonate by basic ring opening of diethyl 2,3-epoxypropylphosphonate. When the latter is allowed to react with MeONa in MeOH at 0°C and then treated with an ion-exchange resin (Dowex SOW), diethyl ( )-3-hydroxy-l-propenylphosphonate is isolated in quantitative yield. " It is converted by room temperature oxidation with PCC in CIFCF into pure diethyl ( )-2-formylvinylphosphonate in 52% yield (Scheme 5.27). 

The dicyclohexylammonium salt of diethyl I -(hydroxycarbonyl )vinylphosphonate appears to be a readily accessible Michael acceptor. It reacts with aldehydes in CgHg at 50°C to provide the desired adducts in satisfactory yields (70-75%). Chromatography using a strongly acidic ion-exchange resin (Dowex 50W) affords the corresponding aldehydes quantitatively (Scheme 5.32). ... 

The preparation of AEP via the reduction of oxime of diethyl 1-formylmethylphosphonate is of synthetic importance. The oxime is prepared from diethyl 1-formylmethylphosphonate and hydroxylamine hydrochloride in EtOH/Py, treated with (AcO)2O in AcOH, and then hydrogenated using 5% Pd/C. After acid hydrolysis using 6 M HCl and purification with ion-exchange resin (Dowex 50W), AEP is isolated in 43% yield. ... 

The 2-amino-4-phosphonobutanoic acid is available by a Michaelis-Arbuzov reaction from triethyl phosphite and ethyl 4-bromobutanoate followed by acid hydrolysis of the ester groups, bromination, and aimnonolysis. After treannent with ion-exchange resin (Dowex SOW), the pure acid is obtained in 48% yield - ... 

The synthesis of phosphonic analogues of aspartic acid and asparagine is accomplished by addition of diethyl phosphite to diethyl acctamidomcthylcncmalonate The sttongly activated double bond readily adds diethyl phosphite in an exothermic reaction catalyzed by EtONa (Scheme 8.84). Hydrolysis of the crude addition product with concentrated HCl at reflux delivers the amino acid purified using acidic ion-exchange resin (Dowex SOW). 

Treatment of protected (o-amino-(o-(alkoxycarbonyl)alkylphosphonates with 4-8 M HCl selectively removes the ester groups to generate the free acids in 70-75% yields. Treatment of acids with acidic ion-exchange resin (Dowex SOW) or with propylene oxide followed by recrystallization from EtOH-H2O affords pure (o-amino-(o-(hydroxycarbonyl)alkylphosphonic acids 890,919,925,927,933... 

PhNHNH2, AcOH, EtOH. This is a standard method that works well for a large variety of substrates. The cationic ion exchange resin Dowex 50-X8 is also a good catalyst for this reaction. ... 

Ion exchange resins Dowex 50 W-X8 from Dow Chemical Co., Midland, Michigan, USA and Amberlite IRC-50 from BDH Chemicals Ltd., Poole, England. 

The effect of binding complex ions to an ion-exchange resin (Dowex SOW) upon the rates of hydrolysis of the [Co(NH3)60Re08] + and [Cr(H20)6Cl] + ions, or the... 

Binding of the [Co(NH3)5(H20)] + ion with an ion-exchange resin (Dowex 50w) has no effect upon the water exchange rate, whereas the pH-dependence for 0-exchange between Hg and [ReOJ" ion is modified on binding to the resin. ... 

Rubber grade 1,3-butadiene was purchased from the Phillips Petroleum Company. Two columns, one packed with the potassium form of a sulfonic acid ion exchange resin (Dowex MSC-l-K) and the other packed with an activated alumina, were used to purify the butadiene. Isoprene was purchased from Aldrich Chemical Company. Stabilizer-free styrene monomer was obtained directly from the Dow styrene monomer plant. Alpha-methylstyrene (AMS) was purchased from U.S. Steel Corporation. The last three monomers were all purified by passing through a column packed with activated alumina and then vacuum distilled over calcium hydride. 

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