Ion-exchangers alkali metal

P-07 - Effects of ion-exchanged alkali metal cations on the photolysis of alkyl ketones included within ZSM-5 zeolite cavities A study of ab-initio molecular orbital calculations... 

Yamashita, H., Nishimura, M., Bessho, H., Takada, S., Nakajima, T, Hada, M., Nakatsuji, H., and Anpo, M., Effect of ion-exchanged alkali metal cations on the photolysis of 2-pentanone included within ZSM-5 zeolite cavities a study of ah initio molecular orbital calculations. Res. Chem. Intermed., 27, 89, 2001. 

The interlayer separation directly depends on the number of water molecules present between the layers. In the anhydrous phases ZrM(P04)2 (M = Mg, Ca, Sr, or Ba) and the half exchanged phases ZrHM(P04)2 (M = Li, Na, K, Rb, or Cs) the interlayer separation is independent of cation size, indicating that the interlayer cavity, which contains one water molecule in the unexchanged compound, is sufficiently large to accommodate a single cation. In contrast, in the fully exchanged alkali metal ion compositions, the interlayer separation increases with increasing cation radius. 

The selective reduction of steroid ketones by means of LiAlH4-activated template polymers can be carried out following the principle of an ion exchanger. Although the application of polymers in template syntheses is currently limited, and the reactions do not always run satisfactorily, this method appears to be a landmark for future rational syntheses. Microporous phases with three-dimensional lattice networks and defined pore structures and sizes can be obtained by the use of molecules or hydrated ions of alkali metals or alkaline earth metals as templates [73]. A concept developed by the Mobil Oil Company for the synthesis of porous materials employs a regular arrangement of molecules formed... 

The various tunable properties of zeolites have inspired a great variety of concepts in electrochemistry with zeolite-modified electrodes. For example, silver ions inside the zeolite pore system arc not electrochemically active in amperometric detection. Flowever, indirect analyte detection can occur when the analyte causes the removal of silver ions into the solution where they are electrochemically detected.[94] This indirect approach was extended to different copper-exchanged zeolites and demonstrated for the detection of several non-elcctroactive ions including alkali metal, ammonium and calcium.[95] A zeolite-modified electrode (ZME) with high selectivity towards Pb over Cd in cyclic voltammetry was prepared via electrophoretic deposition of zeolite Y, coated with Nafion.[96]... 

Carbanions as intermediates have been suggested in the base-catalyzed isomerization of imsaturated nitriles. As long as zeolites with anion-exchange properties are not available, basic centers must be introduced by exchange of the nonframework ions by alkali metal ions or of silicon by germanium, by precipitation... 

Modified Zeolites. As described above, alkali ion-exchanged zeolites are weak bases. Various efforts have been made to increase the base strength of alkali metal-ion exchanged zeolites. Metallic sodium particles in zeolites are formed by the decomposition of occluded sodium azide (59). These sodium particles are capable of performing base-catalyzed reactions. These catalysts catalyze the isomerization of butenes at 300 K and the side-chain alkylation of toluene with ethylene at 523 K. 

AMP-1 4.0 Microcrystalline ammonium molybdo-phosphate with cation exchange capacity of 1.2 mequiv/g. Selectively adsorbs larger alkali metal ions from smaller alkali metal ions, particularly cesium. 

Base catalysis is most effective with alkali metals dispersed on solid supports or, in the homogeneous form, as aldoxides, amides, and so on. Small amounts of promoters form organoalkali comnpounds that really contribute the catalytic power. Basic ion exchange resins also are usebil. Base-catalyzed processes include isomerization and oligomerization of olefins, reactions of olefins with aromatics, and hydrogenation of polynuclear aromatics. 

Separation of Some Alkali Metals Using an Ion Exchange Resin in Conjunction with a Cation Micro-Membrane Ion... 

Triple bonds can also be selectively reduced to double bonds with DIBAL-H, " with activated zinc (see 12-36), with hydrogen and Bi2B-borohydride exchange resin, ° or (internal triple bonds only) with alkali metals (Na, Li) in liquid ammonia or a low-molecular-weight amine.Terminal alkynes are not reduced by the Na—NH3 procedure because they are converted to acetylide ions under these conditions. However, terminal triple bonds can be reduced to double bonds by the... 

The nonnuclear chemistry of Fr reduces to studies of coprecipitation in which Fr shows the behavior of the heavier alkali metal. Coprecipitation is followed by ion exchange to concentrate Fr Physical (mp, density, crystal parameters) and chemical (thermodynamics, solvation entropies) properties are theoretically derived or extrapolated from the trends exhibited by the other alkali metals. 

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