Cation exchanger resin, preparation

The liquid chromatograph used 1n this study consisted of a Cheminert Model CMP-2K (Laboratory Data Control, Riviera Beach, FI.) which is capable of a maximum flow rate of 2 ml/min at a maximum pressure of 500 PSI. This pump has all liquid contact parts limited to glass, teflon or KEL-F materials to reduce corrosion to a minimum. The Injection valve is a Laboratory Data Control Model SU 8031 slider valve with a 0.5 ml sample loop. The injection valve is located at the top of the column to minimize dead volume. The separating column is a Laboratory Data Control type MB glass column, 30 cm long with a 2 mm bore capable of a maximum pressure of 500 PSI. The column is packed with surface sulfonated cation exchanger resin prepared in this laboratory in the following manner. 

A polyfunctional cation-exchange resin prepared by heating a mixture of furfural and /)-phenolsulphonic acid with a prepolymer from furylacrylic add at 60 °C for 5-6 h is stable up to 100 °C, swells 135 % in water (in H form), and possesses static exchange capadty of 4.9-5.0, 2.3, 2.7, and 3.5 meq/g for O.IN NaOH, O.IN CaQj, —COOH groups, and O.IN salsolidine, respectively. 

Definition Potassium salt of a low crosslinked carboxylic cation-exchange resin prepared from methacrylic acid and divinylbenzene Properties Wh. to off-wh. free-flowing powd., odorless to faint odor, tasteless pract. insol. in water and in most liqs. 

Direct, acid catalyzed esterification of acryhc acid is the main route for the manufacture of higher alkyl esters. The most important higher alkyl acrylate is 2-ethyIhexyi acrylate prepared from the available 0x0 alcohol 2-ethyl-1-hexanol (see Alcohols, higher aliphatic). The most common catalysts are sulfuric or toluenesulfonic acid and sulfonic acid functional cation-exchange resins. Solvents are used as entraining agents for the removal of water of reaction. The product is washed with base to remove unreacted acryhc acid and catalyst and then purified by distillation. The esters are obtained in 80—90% yield and in exceUent purity. 

Numerous types of both cation and anion exchange resins have been prepared, but only a few can be mentioned here. Cation exchange resins include that prepared by the copolymerisation of methacrylic acid (E) with glycol... 

Deoxy-6-fluoro-L-ascorbic acid ° (314) was prepared from methyl 2,3-<9-isopropylidene-6-0-tosyl-a-L-gulosonate (313) by reaction with KP followed by isomerization of the product (with H" " cation-exchange resin). 

Palmer showed that F-2DFG prepared from 61 and F2 could be separated, by liquid chromatography on a cation-exchange resin (Aminex-A5, Rb form), from [ F]fluoride and less-polar impurities, but not from F-2DFM. 

Analyses for the Saxitoxins. Early methods for analysis of the saxitoxins evolved from those used for toxin isolation and purification. The principal landmarks in the development of preparative separation techniques for the saxitoxins were 1) the employment of carboxylate cation exchange resins by Schantz et al. (82) 2) the use of the polyacrylamide gel Bio-Gel P2 by Buckley and by Shimizu (5,78) and 3) the development by Buckley of an effective TLC system, including a new solvent mixture and a new visualization technique (83). The solvent mixture, designated by Buckley as "E", remains the best for general resolution of the saxitoxins. The visualization method, oxidation of the saxitoxins on silica gel TLC plates to fluorescent degradation products with hydrogen peroxide and heat, is an adaptation of the Bates and Rapoport fluorescence assay for saxitoxin in solution. Curiously, while peroxide oxidation in solution provides little or no response for the N-l-hydroxy saxitoxins, peroxide spray on TLC plates is a sensitive test for all saxitoxin derivatives with the C-12 gemdiol intact. 

Phosphorous acid has also been of use for additions to imines. Originally investigated by Moedritzer and Irani,241 who developed a Mannich-type procedure for the preparation of phosphorus-centered species, the approach was found later to be useful for both primary and secondary amines in reaction with formaldehyde and phosphorous acid. The approach was later used for the preparation of a cationic exchange resin using a polymer substrate.242... 

Cation exchange resins are mainly used in softening hard water by replacing Ca2+ and Mg2+ ions present in it by Na+ ions. They are also used in analytical and preparative chemistry. 

Wang et al. investigated the catalytic behavior of cation exchange resin supported lanthanide(III) salts of the general structure (31) (Scheme 4.15), prepared from Dowex, Amberlite, Amberlyst and other resins [99]. It turned out that Am-berlyst XN-1010 and Amberlyst 15 complexed best with lanthanides(III). Thus, among others, electrophilic substitution of indole with hexanal and Mukayiama-type aldol reaction of benzaldehyde with ketene silyl acetal proceeded in excellent yields under catalytic conditions (Scheme 4.16). 

Sorbitol easily dehydrates into its 1 4-3 6-dianhydro derivative, isosorbide (III), in the presence of an acid catalyst such as sulfuric, hydrochloric, or toluenesul-fonic acid or a cation exchange resin in a one-step preparation in high yield (75-85%)(1) ... 

Hydrobromic acid also may be prepared by hydrogen exchange with a sodium or potassium bromide solution when the solution is passed through a cation-exchange resin. 

Yttrium sulfate is produced as an intermediate in recovering yttrium from monazite or xenotime (see Yttrium, Recovery). Rare earth sulfates are separated on a cation exchange resin bed. Yttrium fraction is purified by fractional crystallization. Alternatively, yttrium sulfate may be prepared by reacting yttrium oxide with sulfuric acid. 

Polymer-supported persulfonic acid was prepared from potassium persulfate and the cation exchange resin P—SO3H in water. The authors reported various applications of this new oxidizing reagent such as epoxidation of olefins, Baeyer-Villiger reaction and cleavage of disulfide and Af-formylamino acids. 

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