Ion resins

Alkylation of 2-naphthoxide ion (Eq. (6)) occurs mainly on carbon in aqueous solvents and mainly on oxygen in aprotic solvents. The product distribution is often used as a probe of the solvent environment in heterogeneous reactions. Brown and Jenkins 54) found that 40-100 % RS spacer chain catalysts 15 and 16 gave up to 98 % O-benzylation of 2-naphthoxide ion with benzyl bromide. The shorter spacer chain catalyst 16 gave 85% O-alkylation, and a conventional benzyltrimethylammonium ion resin 2 gave about 70 % O-alkylation. Because of low activity, product distribution data were obtained with varied amounts of catalyst and were extrapolated to equimolar amounts of catalyst and substrate to obtain the catalyzed O/C product ratios. Interpretation of the data also was complicated by independent evidence that catalysts 15 adsorbed 2-naphthoxide ion, in addition to that bound by ion exchange54). Essentially the same results were obtained with catalysts 24 which lack the ester link in the spacer chain 106). 

Commercial anion exchange resins have been used extensively for syntheses. A stoichiometric quantity of the anionic reactant is bound to the quaternary ammonium ion resin and allowed to react with an organic substrate in an organic solvent. The resin can be recovered and reused. Since the resins are not catalysts, they are not discussed further here. See other reviews for many examples l6,39,40 41 139). 

On the basis of the charge of the exchangeable ions, there are cation (positive mobile ions) and anion (negative mobile ions) resins. Both types are manufactured from the very same basic organic polymers. However, the ionic groups that are introduced into the matrix... 

Ion exchange processes function by replacing undesirable ions of a liquid with ions such as H+ or OH- from a solid material in which the ions are sufficiently mobile, usually some synthetic resin. Eventually the resin becomes exhausted and may be regenerated by contact with a small amount of solution with a high content of the desired ion. Resins can be tailored to have selective affinities for... 

Pecina et al. (26) used fixed-ion resin columns in hydrogen ion form to separate in a satisfactory way mixtures of low-MW alcohols. At the same time, glycerol is also well resolved from other alcohols present. The authors worked with columns of 300 X 7.8 mm, thermostated at 50°C, using as the eluent a solution of 0.01 N of H2S04 with a flow of 0.7 ml/min and an RI detector. For fast screenings, the use of shorter columns has been suggested (27) with an elu-... 

UOP/Chiyoda Corp. Bisphenol-A Phenol and acetone Process has highest product purity, high selectivity/conversion using proprietary cation-ion resin catalyst, low operating/capital investment costs 3 1998... 

Without access to the ion resin, Bronk and Ward (1999) switched to vacuum distillation to remove NH4+, followed by peroxide oxidation under UV radiation to convert DON to NOs". The nitrate was then reduced to nitrite and isolated by solvent extraction using tricholoroethanol (Olson, 1981) (Section 3.3). As noted above, Miyajima et al. (2005) have recently also analyzed DON by conversion to nitrate but employed GC-MS analysis of the PFB derivative. Their approach has the advantage of requiring small sample sizes, which also permits simply drying the sample to remove NH4+ during the DIN removal step. Clearly, any of the methods for NOs analysis (Section 3.3) would be suitable for this purpose too. 

Ion exchange processes function by replacing undesirable ions of a liquid with ions such as H+ or OH from a solid material in which the ions are sufficiently mobile, usually some synthetic resin. Eventually the resin becomes exhausted and may be regenerated by contact with a small amount of solution with a high content of the desired ion. Resins can be tailored to have selective affinities for particular kinds of ions, for instance, mercury, boron, ferrous iron, or copper in the presence of iron. Physical properties of some commercial ion exchange resins are listed in Table 15.4 together with their ion exchange capacities. The most commonly used sizes are -20 + 50 mesh (0.8-0.3 mm) and -40 -h 80 mesh (0.4-0.18 mm). 

Both empirical and more fundamental relationships have been established to describe and predict equilibrium states for ion exchange systems. Virtually by definition, an empirical model found to suit a particular system being studied is unlikely to apply unchanged to all different circumstances since the empirical coefficients and exponents do not relate to fundamental properties of the ions, resin, and solvent concerned - otherwise the model would not be empirical. 

Diminishing the Flame Production of Explosives , GerP 2530656 (1976) CA 85, 7959 (1976) [The inventor suggests that addn of a cationic ion resin charged vnth enough alkali metal cations to create a neutral reaction in aq soln suppresses flame formation in a doublebase proplnt. Thus, no flame is observed from a compn con NC 89.5, NG 5, DPA 1, DNT 1.5 and TNT 1.5p, to which 1.5p of Lewasorb AlO has been added after activation with K ions]... 

Or Other Cation-Exchange Type, e.g.. Ion Resin, o Carbon... 

A variety of ion exchange resins with strong and weak acid, weak base, and quaternary ammonium ion functionality are available in bead form well suited for filtration from reaction mixtures and for use in continuous flow processes. They have been used for >30 years in flow systems for water deionization. Sulfonic acid resins are already used on a large scale as catalysts for the addition of methanol to isobutylene to form methyl terr-butyl ether, for the hydration of propene to isopropyl alcohol, and for a variety of smaller scale processes. Tertiary amine resins have been used as catalysts for the addition of alcohols to isocyanates to form urethanes. The quaternary ammonium ion resins could be used as reagents with any of a large number of counter ions, and as catalysts in two and three phase reaction mixtures, although the author is not aware of any commercial process of this sort at present. 

The last trace of electrolytes can be removed From silica sol produced by conventional means by heating and again passing it through a hydrogen ion resin to remove alkali liberated from the particles, according to Mindick and Reven (65). 

The fixed ion resin technique, in particular Ca and Ag " forms of resin, is replacing traditional GPC for routine corn syrup analysis in the food industry. The major drawback of these columns includes the compressibility of the gel matrix, extended analysis time, efficiency losses of the order of 50% for a doubling of the flow-rate, the need for high temperature (850 operation, and the need for specialized regeneration and re-packing of contaminated columns. However these drawbacks are offset by the ability to obtain an almost total analysis of material applied to the column and the use of water as the only eluant. 

Discontinuous recovery of CO2. This is required whenever the contents of a batch extractor are discharged or whenever the contents of an activated carbon or ion resin adsorber require changing. In order to minimise the downtime associated with the above operations, the expansion should take place as rapidly as possible, but subject to the following restraints. 

Addition of HF to cyano- and carbonyl-activated triple bonds gives the j8-fluoroalkenes from H2FJ in a macroporous quaternary ammonium ion resin. Fluoride ions resins also are used as bases for alkylations of 2,4-pentanedione and phenols, addition of thiophenol to 3-buten-2-one, and autooxidative sulfenylation of 2,4-pentanedione as shown in equation (19). ... 

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