Ion exchange resins preparation

Pouilloux, Y., Abro, S., Vanhove, C., and Barrault, J. 1999. Reaction of glycerol with fatty acids in the presence of ion-exchange resins preparation of monoglycerides. J. Mol. Cata. A Chem.,149,243-254. 

Also, with ion-exchange resins the same principles ruling pore stability are encountered as were found in their parent matrices. Ion-exchange resins prepared from matrices having sufficient DVB content and relatively wide pores, mostly connected with a high pore volume, retain their volume during removal of solvent better than types having lower pore volumes and smaller pores. 

The choice of the amine can have a substantial influence on the selectivity of the separations, even for simple inorganic ions. The elution behavior is a function of the hydrophobicity of the functional group (5,6). As an example, the retention of inorganic anions on pellicular latex-based ion-exchange resins prepared from different amines is shown in Table 12.1 (5). 

After preparation, colloidal suspensions usually need to undergo purification procedures before detailed studies can be carried out. A common technique for charged particles (typically in aqueous suspension) is dialysis, to deal witli ionic impurities and small solutes. More extensive deionization can be achieved using ion exchange resins. 

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. 

Suspension Polymerization. Suspension polymerisation yields polymer in the form of tiny beads, which ate primarily used as mol ding powders and ion-exchange resins. Most suspension polymers prepared as mol ding powders are poly(methyl methacrylate) copolymers containing up to 20% acrylate for reduced btittieness and improved processibiUty are also common. 

The organic and aqueous phases are prepared in separate tanks before transferring to the reaction ketde. In the manufacture of a styrenic copolymer, predeterrnined amounts of styrene (1) and divinylbenzene (2) are mixed together in the organic phase tank. Styrene is the principal constituent, and is usually about 90—95 wt % of the formulation. The other 5—10% is DVB. It is required to link chains of linear polystyrene together as polymerization proceeds. DVB is referred to as a cross-linker. Without it, functionalized polystyrene would be much too soluble to perform as an ion-exchange resin. Ethylene—methacrylate [97-90-5] and to a lesser degree trivinylbenzene [1322-23-2] are occasionally used as substitutes for DVB. 

Suspension Polymers. Methacrylate suspension polymers are characterized by thek composition and particle-size distribution. Screen analysis is the most common method for determining particle size. Melt-flow characteristics under various conditions of heat and pressure are important for polymers intended for extmsion or injection molding appHcations. Suspension polymers prepared as ion-exchange resins are characterized by thek ion-exchange capacity, density (apparent and wet), solvent sweUing, moisture holding capacity, porosity, and salt-spHtting characteristics (105). 

In Canada, ion-exchange (qv) technology has been used to produce potassium sulfate (4). Ion-exchange resins remove sulfate ions from lake water containing sodium sulfate. This is followed by a wash with aqueous solutions prepared from lower grade muriate of potash. High purity potassium sulfate is collected from the crystallizers into which the wash mns. 

ButylatedPhenols and Cresols. Butylated phenols and cresols, used primarily as oxidation inhibitors and chain terrninators, are manufactured by direct alkylation of the phenol using a wide variety of conditions and acid catalysts, including sulfuric acid, -toluenesulfonic acid, and sulfonic acid ion-exchange resins (110,111). By use of a small amount of catalyst and short residence times, the first-formed, ortho-alkylated products can be made to predominate. Eor the preparation of the 2,6-substituted products, aluminum phenoxides generated in situ from the phenol being alkylated are used as catalyst. Reaction conditions are controlled to minimise formation of the thermodynamically favored 4-substituted products (see Alkylphenols). The most commonly used is -/ fZ-butylphenol [98-54-4] for manufacture of phenoHc resins. The tert-huty group leaves only two rather than three active sites for condensation with formaldehyde and thus modifies the characteristics of the resin. 

Brine Preparation. Rock salt and solar salt (see Chemicals frombrine) can be used for preparing sodium chloride solution for electrolysis. These salts contain Ca, Mg, and other impurities that must be removed prior to electrolysis. Otherwise these impurities are deposited on electrodes and increase the energy requirements. The raw brine can be treated by addition of sodium carbonate and hydroxide to reduce calcium and magnesium levels to below 10 ppm. If further reduction in hardness is required, an ion-exchange resin can be used. A typical brine specification for the Huron chlorate ceU design is given in Table 6. 

Ion-exchange resins swell in water to an extent which depends on the amount of crosslinking in the polymer, so that columns should be prepared from the wet material by adding it as a suspension in water to a tube already partially filled with water. (This also avoids trapping air bubbles.) The exchange capacity of a resin is commonly expressed as mg equiv./mL of wet resin. This quantity is pH-dependent for weak-acid or weak-base resins but is constant at about 0.6-2 for most strong-acid or strong-base types. 

Ion exchange resins are also useful for demineralising biochemical preparations such as proteins. Removal of metal ions from protein solutions using polystyrene-based resins, however, may lead to protein denaturation. This difficulty may be avoided by using a weakly acidic cation exchanger such as Bio-Rex 70. 

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. 

The DNP derivative, prepared from 2,4-dinitrofluorobenzene is released from the nitrogen with an anionic ion exchange resin." When used for histidine protection, the DNP group has been observed to migrate to nearby [ysine residues during Fmoc cleavage. ... 

Ion exchange resin synthesis paths for the preparation of ionic liquids (adapted from... 

Ion exchange column. Prepare the Chelex-100 resin (100- 500 mesh) by digesting it with excess (about 2-3 bed-volumes) of 2M nitric acid at room temperature. Repeat this process twice and then transfer sufficient resin to fill a 1.0 cm diameter column to a depth of 8 cm. Wash the resin column with several bed-volumes of de-ionised water. 

ALKENES via HOFMANN ELIMINATION USE OF ION-EXCHANGE RESIN FOR PREPARATION OF QUATERNARY AMMONIUM HYDROXIDES DIPHENYLMETHYL VINYL ETHER... 

The free oil can be determined by an ion exchange HPLC technique. A solution of the sample in ethyl alcohol is analysed by high-performance ion exchange chromatography using a specially prepared ion exchange resin stationary phase, ethanol mobile phase, and differential refractive index detection. 

A synthesis of 5-(aioylamino)-2-aryloxazoles 39 is outlined in Scheme 9. Heating the glycol 37 (Bt = benzotriazol-l-yl), prepared from glyoxal and benzotriazole, with an amide in the presence of an ion exchange resin yields the acylated diamine 38, which cyclises by the action of sodium hydiide in DMF <95JHC1651>. 

---