Dowes® ion exchanger resin

One important factor to consider in the preparation of the organic phase is the presence of inhibitors in the monomers. Some formulae call for the removal of inhibitors, primarily TCB, from the monomers. The TCB inhibitor forms highly colored complexes with metallic salts rendering the final product colored. Styrene has about 50 ppm of TCB. DVB, being more reactive, contains about 1000 ppm of TCB. There are several options for the removal of inhibitors. Columns packed with DOWEX MSA-1 or DOWEX 11 ion-exchange resins (Dow Chemical Company) can be used. White drierite or activated alumina also works well. 

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). 

Dow Chemical Company, Dowex ion exchange resins product data sheet, http //www.dow.com/liquidseps/prod/ prd dowx.htm, 20 August 2006. 

T0209 Dow Chemical Company, DOWEX Ion Exchange Resins... 

Dow Chemical Company Dowex Ion Exchange Resins Abstract... 

Dowex ion exchange resins include a range of anion and cation resins for multibed demineralization, mixed-bed condensate polishing, as well as nuclear and other specialty applications. Most Dowex resins are based on styrene copolymerized with divinylbenzene (DVB). According to Dow, styrene/DVB structures are the preferred matrices for ion exchange resins because... 

Trade literature published by the manufacturers of ion exchange resins is a valuable source of information. These manufacturers include the Chemical Process Co., Redwood City, Calif. Dow Chemical Co., Midland, Mich. and Rohm and Haas, Philadelphia, Pa. 

Installations The Dow Chemical Co. (Dow), developed their ion exchange resin based BPA technology in the late 1960 s. Dow has continued to improve the technology, especially in the areas of product quality, higher operating efficiency and reduced capital cost. Dow has a total production capacity exceeding 300,000 mty in four plants located in Texas and Stade, Germany. 

Resin requirements for two extremes of ion concentration are analyzed in Example 15.3. The high concentration stream clearly is a candidate for continuous ion exchange. Manufacturers and distributors of ion exchange resins are Dow, Rohm and Haas, Bayer, Kasai, Sybron Chemical and Purolite. 

HCR [Dow], TM applied to ion-exchange resin used in water-treating and chemical process applications strong acid cation-exchange resin, 8% divinylbenzene cross-linked. 

Dow, "Dowex Marathon C, Ion Exchange Resins Engineering Information, Dow Chemical Company, Midland, Michigan, 2002. 

Sulfonic acid resins can be used as solid catalysts for esterifications and other acid-catalyzed reactions. Am-berlyst 15 was a more effective catalyst for the preparation of esters of phenethyl alcohol and cyclohexanol than sulfated zirconia, an acid clay, and dodecatungstophos-phoric acid.113 (Amberlyst and Amberlite are trademarks of Rohm Haas.) (See Chap. 6 for more detail on solid acids and bases.) The same catalyst gave 86-96% yields of hydroxyesters when a lactone was stored with a hy-droxyacid.114 Diols can be monoacylated in 58-92% yields by transesterification with ethyl propionate in the presence of Dowex 50W (a product of the Dow Chemical Co.).115 Modification of the sulfonic acid resin with 2-mercaptoethylamine produced a catalyst for the reaction of phenol with acetone to produce bisphenol A (5.30) in 99.5% yield.116 After 20 cycles the yield was still 98.7%. When used as catalysts, ion-exchange resins can last for 6 months to 2 years. 

Even in 1960 a catalytic route was considered the answer to the pollution problem and the by-product sulfate, but neady ten years elapsed before a process was developed that could be used commercially. Some of the earlier attempts included hydrolysis of acrylonitrile on a sulfonic acid ion-exchange resin (69). Manganese dioxide showed some catalytic activity (70), and copper ions present in two different valence states were described as catalytically active (71), but copper metal by itself was not active. A variety of catalysts, such as Urushibara or Ullmann copper and nickel, were used for the hydrolysis of aromatic nitriles, but aliphatic nitriles did not react using these catalysts (72). Beginning in 1971 a series of patents were issued to The Dow Chemical Company (73) describing the use of copper metal catalysis. Full-scale production was achieved the same year. A solution of acrylonitrile in water was passed over a fixed bed of copper catalyst at 85°C, which produced a solution of acrylamide in water with very high conversions and selectivities to acrylamide. 

Ion exchange resins Dowex 50 W-X8 from Dow Chemical Co., Midland, Michigan, USA and Amberlite IRC-50 from BDH Chemicals Ltd., Poole, England. 

Dowex. [Dow] Catalysts for prod, of motor fuel oxygenates ion exchange resins. 

Ion-exchange resins Dow, Purohte, ResinTech, Rohm Haas, Sybron, USFilter... 

Rubber grade 1,3-butadiene was purchased from the Phillips Petroleum Company. Two columns, one packed with the potassium form of a sulfonic acid ion exchange resin (Dowex MSC-l-K) and the other packed with an activated alumina, were used to purify the butadiene. Isoprene was purchased from Aldrich Chemical Company. Stabilizer-free styrene monomer was obtained directly from the Dow styrene monomer plant. Alpha-methylstyrene (AMS) was purchased from U.S. Steel Corporation. The last three monomers were all purified by passing through a column packed with activated alumina and then vacuum distilled over calcium hydride. 

In the early 1970s, ion chromatography was developed by Hamish Small and co-workers at Dow Chemical Company as a novel method of lEC usable in automated analysis. This later led to the formation of Dionex Corp (Dow -Ion Exchange). IC uses weaker ionic resins for its stationary phase and an additional neutralizing stripper, or suppressor, column to remove background eluent ions. It is a powerful technique for determining low concentrations of ions and is especially useful in environmental and water quality studies, among other applications. 

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