نتایج جستجو برای: 120 cation exchange resin
تعداد نتایج: 340849 فیلتر نتایج به سال:
in this thesis, a better reaction conditions for the synthesis of spirobarbiturates catalyzed by task-specific ionic liquid (2-hydroxy-n-(2-hydroxyethyl)-n,n-dimethylethanaminium formate), calcium hypochlorite ca(ocl)2 or n-bromosuccinimide (nbs) in the presence of water at room temperature by ultrasonic technique is provided. the design and synthesis of spirocycles is a challenging task becaus...
Adsorption equilibrium of fructose, glucose and sucrose was evaluated on sulfonated poly(styrene-co-divinylbenzene) cation-exchange resins. Two types of resins were used: potassium (K+) gel-type and sodium (Na+) macroporous resins. Influence of the cation and effect of the resin structure on adsorption were studied. The adsorption isotherms were determined by the static method in batch mode for...
The first catalytic asymmetric Fischer indolization is reported. In the presence of a 5 mol % loading of a novel spirocyclic chiral phosphoric acid, 4-substituted cyclohexanone-derived phenylhydrazones undergo a highly enantioselective indolization. Efficient catalyst turnover was achieved by the addition of a weakly acidic cation exchange resin, which removes the generated ammonia. The reactio...
Various organic solutions are used in many industries such as the petrochemical industry. The presence of moisture in those solvents results in poor insulation, corrosion of apparatus and catalyst poisoning. Therefore, the moisture content of the solvents must be reduced to less than several ppm. Since ion exchange resins have an ability to adsorb selectively polar substances fromnonpolar solve...
An improved method is described for the separation of 22 compounds normally related to purine and 6-thiopurine metabolism in biological materials using high-pressure liquid cation-exchange chromatography on strongly acidic exchange resin. The column (0.8 X 100 cm) is eluted with 0.4 M ammonium formate, pH 4.6, at a linear flow velocity of 5.2 cm.min--1 at 50 degrees C. The elution volumes of su...
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