Resinous cation exchangers, chemical

Figure 6 Fractional attainment U(t) of equilibrium for the exchange, Cs /H, by a resin cation exchanger (0.4- and 0.8-mm particles in diameter), when added individually to a CsCl solution (c = 0.0001 M). (+-M-) experimental values. Solid lines calculated curve based on rate coefficients R, obtained for the two size fractions with Eq. (33). (Reprinted with permission from Ref. 26, Copyright 1991 American Chemical Society.)...

Phenol was the 33rd highest-volume chemical. The 1994 U.S. production of phenol was approximately 4 billion pounds. The current world capacity is approximately 15 billion pounds. Many chemicals and polymers derive from phenol. Approximately 50% of production goes to phenolic resins. Phenol and acetone produce bis-phenol A, an important monomer for epoxy resins and polycarbonates. It is produced by condensing acetone and phenol in the presence of HCI, or by using a cation exchange resin. Figure 10-8 shows the Chiyoda Corp. bisphenol A process. 

The copolymer produced in this way has been found to be insoluble and infusible but is still chemically reactive. On heating the polymer with a mixture of sulphur trioxide and sulphuric acid, the sulphonic acid group gets introduced into the aromatic rings. The resin so formed is known as a cation exchanger. 

Cation-exchange resins are used as catalysts in the produdion of MTBE (methyl tertiary-butyl ether, 2-methoxy-2-methylpropane) and various other oxygenates and, lately, also in the dimerization of isobutene [30]. Other commercial applications of the cation-exchange resins indude dehydration of alcohols, alkylation of phenols, condensation readions, alkene hydration, purification of phenol, ester hydrolysis and other reactions [31]. The major producers of ion-exchange resins are Sybron Chemicals Incorporated [32] (Lewatit resins), Dow Chemical Company [33] (DOWEX resins), Purolite [28] (Purolite resins), and Rohm and Haas Company [27] (Amberlyst resins). 

Separation and quantitation of carbohydrate mixtures may be achieved using HPLC, a method that does not necessitate the formation of a volatile derivative as in GLC. Both partition and ion-exchange techniques have been used with either ultraviolet or refractive index detectors. Partition chromatography is usually performed in the reverse phase mode using a chemically bonded stationary phase and acetonitrile (80 20) in 0.1 mol U1 acetic acid as the mobile phase. Anion- and cation-exchange resins have both been used. Carbohydrates... 

I Brand Name(s) Kayexalate, Kionex, SPS Chemical Class Cation exchange resin... 

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