Macroreticular cationic resins

New Macroreticular Cationic Resins from Natural Products... 

Esterification. Extensive commercial use is made of primary amyl acetate, a mixture of 1-pentyl acetate [28-63-7] and 2-metliylbutyl acetate [53496-15-4]. Esterifications with acetic acid are generally conducted in the Hquid phase in the presence of a strong acid catalyst such as sulfuric acid (34). Increased reaction rates are reported when esterifications are carried out in the presence of heteropoly acids supported on macroreticular cation-exchange resins (35) and 2eohte (36) catalysts in a heterogeneous process. Judging from the many patents issued in recent years, there appears to be considerable effort underway to find an appropriate soHd catalyst for a reactive distillation esterification process to avoid the product removal difficulties of the conventional process. 

MTBE is currently synthesized industrially from methanol and isobutene over an acidic ion-exchange resin, mostly Amberlyst 15 which is in fact a macroreticular cation-exchange resin [1,2]. ETBE which is obtained by reaction of isobutene with ethanol, is also an attractive octane enhancer for gasoline [3]. Although the commercial catalyst is very efficient, it suffers from several drawbacks such as thermal instability, acid leaching from the resin... 

Moeur, H. R, Swatik, S. A., and Pinnell, R. P. Microscale Dehydration of Cyclohexanol Using a Macroreticular Cation Exchange Resin. Journal of Chemical Education, 74 (July 1997) 833. 

Bio-Rex 70 2.4 0.70 Weakly acidic cation exchanger with car-boxylate groups on a macroreticular acrylic matrix for separation and fractionation of proteins, peptides, enzymes, and amines, particularly high molecular weight solutes. Does not denature proteins as do styrene-based resins. 

Cation exchange resin— -macroreticular type- — sulfonic acid functionality... 

Macroporous cation exchangers, 14 387 Macroporous gels, 13 738 Macroporous molecular sieves, 16 849 Macroporous particles, apparent effective diffusivity and, 15 730 Macroporous resins, 14 393, 397 Macroreticular sulfonated styrene-... 

Yamabe, K., Ihara, T., Jyo, A., Metal ion selectivity of macroreticular chelating cation exchange resins with phosphonic acid groups attached to phenyl groups of a styrene-divinylbenzene copolymer matrix, Sep. Sci. Technol. 36,2001,3511-3528. 

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. 

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. 

Figure 25-1, p. 290, is a detail of the resin composition, Bio-Rad AG 11A8, in which the anion portion is a quaternary amine and the cation portion is carboxylic acid. Figure 25-2, p. 290, illustrates this technique with the same resin. This type of resin was developed in 1957 (Hatch, M.J., Dillon, J.A., and Smith, H.D., Ind. Eng. Chem., 49, 1812). They used a resin that had very little cross-linking called a macroreticular resin, which has very large openings... 

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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