Sulfonic acid cation

The choice of catalyst is based primarily on economic effects and product purity requirements. More recentiy, the handling of waste associated with the choice of catalyst has become an important factor in the economic evaluation. Catalysts that produce less waste and more easily handled waste by-products are strongly preferred by alkylphenol producers. Some commonly used catalysts are sulfuric acid, boron trifluoride, aluminum phenoxide, methanesulfonic acid, toluene—xylene sulfonic acid, cationic-exchange resin, acidic clays, and modified zeoHtes. 

Also, nylon-6 waste may be hydrolyzed in the presence of an aqueous alkali metal hydroxide or acid5 to produce an alkali metal or acid salt of 6-aminocaproic acid (ACA). The reaction of nylon-6 waste with dilute hydrochloric acid is rapid at 90- 100°C. The reaction mixture is poured into water to form a dilute aqueous solution of the ACA salt. Filtration is used to remove undissolved impurities such as pigments, additives, and fillers followed by treatment of the acid solution with a strong cation exchange resin. A sulfonic acid cationic exchanger absorbs ACA salt and pure ACA is eluted with ammonium hydroxide to form a dilute aqueous solution. Pure ACA is obtained by crystallization of die solution. 

Sulfonic acid cation-exchange resin Quarternary ammonium... 

Min et al. [17] Glucose L-Lactate Lactococcus lactis (ATCC 19435) fermentation Glucose oxidase (GOx) or L-lactate oxidase (LOx) with horseradish peroxidase (HRP)/in a carbon paste matrix with polyethyleneimine and a polyester sulfonic acid cation exchanger (Eastman AQ-29D) Carbon paste electrode/-50 mV vs. Agf AgCl ... 

Resin Beads. The resin beads are prepared from commercially available Dowex 50W-X8, a sulfonic acid cation exchange resin. The 8% cross-linked resin was chosen because it does not shrink or expand excessively in acid-water systems and because it is readily available. Resin cross-linkage had no detectable effect on the final oxide products in the development test runs. The resin is hydraulically classified to produce a size fraction that is predominately 60-80 m in diameter. The classified resin is washed with 6 M HC1 to remove contaminants such as iron and rinsed thoroughly with water. 

In our case a 6% Si02 solution of polysilicic acid was prepared by deionizing to pH 3 a dilute solution of filtered Du Pont JM grade sodium silicate with Dowex HCR-W2-H resin, a strongly acidic nuclear sulfonic acid cation exchanger supplied by Dow Chemical Company. 

Electrodes doped with mediators are also successful in analyses using NAD (P)-dependent dehydrogenases (86-88). In these cases, the mediator is firmly adsorbed to the electrode. The cofactor is oxidized by the mediator, which becomes reduced. The mediator is reoxidized by an electrochemical process on the electrode. This technology makes it possible to reduce the amount of cofactor needed, for example, in flow injection analysis and also eliminates the need for enzymatic regeneration systems. A further successful development uses a carbon paste chemically modified with a dehydrogenase, the coenzyme, and a phenoxazine mediator. This complex structure is then coated with a polyester sulfonic acid cation exchanger (86). The mediators used are of aromatic polycyclic structure and are firmly bound to graphite or other carbon electrodes (Fig. 2) (89). 

Ferromagnetic phenol-formaldehyde sulfonic acid cation-exchange resin has been synthesized by heating a mixture of phenolsulfonic acid and formalin containing magnesium ferrite at 65 °C for 3 h. 

To obtain potassium nitrate from chloride the strong sulfonic acid cation exchanger was converted to the K+-ion form and treated with 4 M HNO3 [43] or with 3-5 M NH4NO3 [56]. 

Ion-exchange chromatography is widely used to separate and analyze mixtures of amino acids. The most common ion-exchange resin used for this purpose is a sulfonic acid cation exchanger of the Dowex-50 (polystyrene) type. The structure of the resin is ... 

K 16. — E. F. Meitzcter, J. A. Oune, S. A. Fisher, and N. Frisch Characterization of Amberlyst 15 macroreticnlar sulfonic acid cation exchange resins. 

R 9. Rohm Haas Company Sulfonic acid cation exchange r in catalysts and chemical reactions involving the use thereof. Brit. Pat 956.357 (1964). 

Scheme 2.1 Condensation polymerization synthesis of a sulfonic acid cation exchange resin...

Table 4.4 Comparison of measured and calculated dry weight capacities of sulfonic acid cation exchange resins...

Water vapour sorption isotherms for a 10% crosslinked sulfonic acid cation exchanger and a 0.4% crosslinked reference resin are shown in Figure 5.2 together with a calculation of the swelling pressure. The anomalous relative positions of the curves at low values of relative humidity P/Pq may be explained in terms of van der Waals type intramolecular forces which weakly bind adjacent polymer chains in de-swollen exchangers of low crosslinking. 

Matantseva and co-workers87,101,103 separated the major opium alkaloids on a pellicular sulfonic acid cation-exchange stationary phase, using a pH 4.5 phosphate buffer containing 30% acetonitrile as mobile phase. 

Table 2 Effective diffusion coefficients for zinc ion in sulfonic acid cation resins of different cross-linking...

Cation Exchange Extractants. This class of extractants includes phenols, branched alkyl carboxylic acids, alkyl phosphoric acids, diketones, and alkyl-aryl sulfonic acids. The last group listed, sulfonic acids, are analogous to sulfonic-acid cation exchange resins and have very little selectivity. Diketones, alkyl phosphoric acids and carboxylic acids can provide both cation exchange functions and coordination functions. This feature has made bis(2-ethylhexyl)phosphoric acid one of the most versatile and powerful extractants of this type. (5) The nation below illustrates simple cation exchange extraction. 

Mixtures of carriers (ionic additiues). Cotransport of opposite-charged ions is the most obvious way to maintain electroneutrality, but alternative means may be explored as additives to LM. In recent years, many studies have been conducted which examine the use of anionic membrane additives for maintenance of electroneutrahty at cation transport [65, 84-89]. The anionic additives are typically fipophific carboxylic, phosphoric, or sulfonic acids. Cation or neutral macrocychc carriers coupled with anionic additives result in a synergistic transport of cations which exceeds that accomplished by each component individuaUy. This synergism was demonstrated in Ref. [90]. The authors observed a 10- to 100-fold enhancement of copper extraction. Enhanced extraction is achieved by adding the anionic group to the cation coordination macrocycle. 

Excellent separations of all the alkali metal cations plus ammonium in 10 min or less with a strong acid (sulfonic acid) cation exchanger and a dilute solution of a strong acid as the eluent (incomplete sentence). However, divalent metal cations are more strongly retained by this column and require either an eluent containing a divalent cation or a more concentrated solution of the H eluent. 

Since it is a zwitterion, cephalosporin C can also be adsorbed on low cross-linked sulfonic acid cation exchange resins, as shown in Figure 5, Although used successfully for cephamycin C (15), a related 8-lactam antibiotic, the strong acidity of these resins results in substantial degradation of cephalosporin C to its lactone. (Cephamycin C contains a carbamoyl ester in place of the acetyl ester at C-3, and is apparently more stable.) Elution of the adsorbed cephalosporin C with acetate buffers yields eluates with high lactone content. 

Figure 13. Average pore diameter of sulfonic acid cation exchange resin as a function of degree of cross-linking. (Ref. 20, page 46)...

All modern resins are polymeric structures, gnuerally hased on either a styrene or an acrylic matrix. Polystyrene Sulfonic Acid Cation Resins... 

---