Using the Ion-Exchange Resin

Dimethylamine (109), putrescine (111), and spermidine (110), isolated from various insects (Table VIII), were obtained as p,p -nitrophenylazobenzoyl, p-phenylazobenzenesulfonyl, and I-dimethylaminonaphthalene-5-sulfonyl (dan-syl) derivatives and picrates or were detected by high-performance liquid chromatography (HPLC) using the ion-exchange resin (106,343). V,V-Dimethyl-3-phenylethylamine (131) from spiders of the genus Sclerobunus (Table VIII) has been identified by mass spectral comparison with a synthetic sample (117). 

The effluent stream from the stack contained a high moisture content and even under these conditions the method functioned properly. The results shown in Table XIV show that a proportional increase in concentration was obtained as the charge rate increased. Appendix A describes the analytical method in total using the ion exchange resin as the sampling adsorbent. 

For anions such as F, MeO or MesSiO, anion exchange can be carried out in solvents such as dimethylsulfoxide by reacting the metal salt of the anion with the peralkylated polyaminophosphonium chloride. Yields are typically around 85% after work-up. Using the ion-exchange resin method yields products that contain typically 20 ppm methanol and between 10 and 15% w/w water, which solvate and stabilize the ion-pair. Dehydration of the catalyst results in... 

In most ion exchange operations, an ion in solution is replaced with an ion from the resin and the former solution ion remains with the resin. In contrast, ion exchange chromatography uses the ion exchange resin as an adsorption or separation media, which provides an ionic environment, allowing two or more solutes in the feed stream to be separated. The feed solution is added to the chromatographic column filled with the separation beads and is eluted with solvent, often water in the case of fermentation products. The resin beads selectively slow some solutes while others are eluted down the column (Fig. 1). As the solutes move down the column, they separate and their individual purity increases. Eventually, the solutes appear at different times at the column outlet where each can be drawn off separately. 

Matouq et al [3.31] tested two types of catalysts an ion exchange-resin (the form of Amberlyst 15) and a heteropolyacid (HPA) in the production of MTBE from methanol and -butyl alcohol (TBA). Both were shown, active, but the ion-exchange resin showed poor selectivity, producing substantial amounts of by-product isobutylene (IB). Matouq et al. [3.31] tested the production of MTBE using the ion-exchange resin in a reactive distillation column. It was difficult to test the HPA catalyst in the reactive distillation system, however, because its particle size was too small and was carried out by the liquid phase. Matouq et al. [3.31] proposed, instead, the use of a PVMR incorporating a PVA membrane. As shown in Figure 3.9, in the proposed system the PVMR is coupled with a con-... 

To ensure the lowest possible ionic strength, the suspensions are sealed in contact with a mixed bed of ion exchanger resins in cylindrical quartz cells 5 days prior to the experiments. Before use the ion exchange resin is washed several times with ultrapure water till we find that a small amount of water that has been in contact with the resin for several days does not contain any contamination, such as polyelectrolyte, that absorb in the UV range [17]. 

The purified commercial di-n-butyl d-tartrate, m.p. 22°, may be used. It may be prepared by using the procedure described under i o-propyl lactate (Section 111,102). Place a mixture of 75 g. of d-tartaric acid, 10 g. of Zeo-Karb 225/H, 110 g. (136 ml.) of redistilled n-butyl alcohol and 150 ml. of sodium-dried benzene in a 1-litre three-necked flask equipped with a mercury-sealed stirrer, a double surface condenser and an automatic water separator (see Fig. Ill, 126,1). Reflux the mixture with stirring for 10 hours about 21 ml. of water collect in the water separator. FUter off the ion-exchange resin at the pump and wash it with two 30-40 ml. portions of hot benzene. Wash the combined filtrate and washings with two 75 ml. portions of saturated sodium bicarbonate solution, followed by lOu ml. of water, and dry over anhydrous magnesium sulphate. Remove the benzene by distillation under reduced pressure (water pump) and finally distil the residue. Collect the di-n-butyl d-tartrate at 150°/1 5 mm. The yield is 90 g. 

This is the basis of their use as ion exchange resins. The resin can be regenerated by treatment with dilute acids. Further developments have... 

Removal of brine contaminants accounts for a significant portion of overall chlor—alkali production cost, especially for the membrane process. Moreover, part or all of the depleted brine from mercury and membrane cells must first be dechlorinated to recover the dissolved chlorine and to prevent corrosion during further processing. In a typical membrane plant, HCl is added to Hberate chlorine, then a vacuum is appHed to recover it. A reducing agent such as sodium sulfite is added to remove the final traces because chlorine would adversely react with the ion-exchange resins used later in the process. Dechlorinated brine is then resaturated with soHd salt for further use. 

The Asahi process (Fig. 16-63) is used principally for high-volume water treatment. The hquid to be treated is passed upward through a resin bed in the adsorption tank. The upward flow at 30-40 m/h [12-16 gal/(min ft")] keeps the bed packed against the top. After a preset time, 10 to 60 min, the flow is interrupted for about 30 s, allowing the entire bed to drop. A small portion (10 percent or less) of the ion-exchange resin is removed from the bottom of the adsorption tank and transferred hydraulically to the hopper feeding the regeneration tank. 

To be suitable for industrial use, an ion-exchange resin must exhibit durable physical and chemical characteristics which are summarized by the following properties. 

Solubility - The ion-exchange substance must be insoluble under normal conditions of use. Most ion-exchange resins in current use are high molecular weight... 

If the ion-exchange resin is used for removing phenol, it is regenerated by employing caustic soda to convert phenol into sodium phenoxide (a salable compound) according to the following reaction ... 

The structures of these ylide polymers were determined and confirmed by IR and NMR spectra. These were the first stable sulfonium ylide polymers reported in the literature. They are very important for such industrial uses as ion-exchange resins, polymer supports, peptide synthesis, polymeric reagent, and polyelectrolytes. Also in 1977, Hass and Moreau [60] found that when poly(4-vinylpyridine) was quaternized with bromomalonamide, two polymeric quaternary salts resulted. These polyelectrolyte products were subjected to thermal decyana-tion at 7200°C to give isocyanic acid or its isomer, cyanic acid. The addition of base to the solution of polyelectro-lyte in water gave a yellow polymeric ylide. 

In recent years, the rate of information available on the use of ion-exchange resins as reaction catalysts has increased, and the practical application of ion-exchanger catalysis in the field of chemistry has been widely developed. Ion-exchangers are already used in more than twenty types of different chemical reactions. Some of the significant examples of the applications of ion-exchange catalysis are in hydration [1,2], dehydration [3,4], esterification [5,6], alkylation [7], condensation [8-11], and polymerization, and isomerization reactions [12-14]. Cationic resins in form, also used as catalysts in the hydrolysis reactions, and the literature on hydrolysis itself is quite extensive [15-28], Several types of ion exchange catalysts have been used in the hydrolysis of different compounds. Some of these are given in Table 1. 

There are several apparent advantages to the use of ion-exchange resins as either acid or base catalysts, several of which are as follows ... 

The LLW from nuclear power plants contains ion exchange resins as well as clothing, tools, and chemicals. Ion exchange resins, which comprise the majority of this LLW, are used to filter the water circulated in nuclear power plants. The ion exchange resins isolate and trap dissolved materials, much of which can be radioactive. Approximately three-fourths of commercially or privately generated LLW is in the form of the contaminated plastic beads that make up ion exchange resins. 

The most important minerals of the lanthanide elements are monazite (phosphates of La, Ce, Pr, Nd and Sm, as well as thorium oxide) plus cerite and gadolinite (silicates of these elements). Separation is difficult because of the chemical similarity of the lanthanides. Fractional crystallization, complex formation, and selective adsorption and elution using an ion exchange resin (chromatography) are the most successful methods. 

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