Macroreticular polystyrene sulfonate

Stationary Phase Use prepacked macroreticular polystyrene sulfonate divinylbenzene cation-exchange resin (2% to 8% cross-linked, 8- to 25-ptm particle size), preferably in the calcium or silver form. Examples of acceptable resins are Bio-Rad Aminex HPX-87C, or equivalent, for separating DPi-DP4 saccharides, and Aminex HPX-42C and HPX-42A, or equivalent, for separating DP1-DP7 saccharides. Maintain the column at 85° during operation. 

Ainberlyst-type catalysts were as active as and more selective than the best homogeneous catalyst, II2SO4. Amberlyst 15 and 3G are macroreticular type polystyrene sulfonic acid resins partially cross-linked with divinylbenzene. The absence of the N—benzyl product when solid acid catalysts were employed suggests the possibility that the reaction could be carried out in a single step. It is also expected to provide all the aforementioned advantages of solid catalysts over liquid catalysts. 

Zhao and co-workers848 synthesized macroreticular para-( -sulfonic-perfluor-oalkylated) polystyrene (FPS) and used it in the cyclization of pseudoionone into a-ionone 241a an important fragrance material. The ring closure induced by the catalyst led to complete conversion and the product was formed in low yield but selectively (/3-ionone was not observed) [Eq. (5.309)]. Amberlyst proved to be less active and less selective. A new catalyst loaded with perfluoroalkanesulfonic as well as phenylsul-fonic acid groups (FPSS) exhibited improved performance849 [Eq. (5.309)]. 

Ag and Co functionalized adsorbents for the PPhs adsorption. These transition-metal functionalized adsorbents were prepared by immobilizing Ag and Co onto a solid carrier, for which Amberlyst IS has been selected. Amberlyst 15, a macroreticular polystyrene - crosslinked by divinylbenzene - sulfonated cation exchange resin, has been selected as carrier because of its large pore diameter of approximately 100 [nm]. These macropores ensure the accessibility for the relatively large PPh3 ligands. 

Paul et al. (25) observed that for polymer volume fractions less than 0.8, the functional dependence of the diffusion coefficients on the polymer volume fraction was, generally, in accordance with Equation 40. Muhr and Blanshard (26) provide additional supporting data on different polymers than those reported by Paul et al, Roucls and Ekerdt (27) measured the diffusion of cyclic hydrocarbons in benzene-swollen polystyrene beads their diffusion coefficients satisfy the general form of Equation 40. The effective dlffuslvltles of organic substrates in crossllnked polystyrene reported by Marconi and Ford (17) also follow trends predicted in Equation 40. In the absence of experimental data, it appears that Equation 40 provides a reasonable, and the simplest, means to estimate D for use in detailed modeling or in estimation methods such as Equation 38. Equation 40 was used by Dooley et al. (11) in their study of substrate diffusion and reaction in a macroreticular sulfonic acid resin which involved vapor phase reactants. 

The most widely used catalysts for acid-catalyzed aldol condensations are the molecular sieve zeolites, for example, crystalline aluminosilicates of group I and II elements, in which the latter have been replaced by protons. The surface protons confer Br0nsted acidity. Among the acidic zeolites we can mention HZSM-5 (pentasil zeolite), HY (faujasite), or HM (mordenite). Recently, polystyrene-supported sulfonic acids such as those of the macroreticular strongly acidic cation-exchange resins (59) and acid-base functionalized mesoporous materials such as amine and sulfonic acid-containing SBA-15 (60) have been shown to promote the acid-catalyzed aldol condensation of aldehydes with ketones at low temperatures. 

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