Amberlite resin

Several improved methods for the nitration of alkyl halides have been reported. For example, the use of KN02 in the presence of lS-crown-694 or nitrite ion bounded to macroporous quaternary ammonium amberlite resin (amberlite IRA 900) improves the yield of nitro compounds (Eq. 2.49) 95... 

Rate = /cobsd[H + ][RuH]. Conditions 70 mg of the complex and 2 g of Amberlite resin IRA-400(C1) were dissolved in 30 ml H20, stirred for 6 h, filtered, and stored at 5 °C. Reaction mixtures were made by mixing 2.5 cm3 Britten-Robinson buffer (ionic strength 0.12 mol/L, pH between 2 and 3) with 0.5 cm3 of the Ru-hydride solution. 

In order to look at the probable duration of treatment with topical agents for colonic drug delivery, we have conducted studies with normal subjects and patients with left-sided colitis. The subjects and patients were dosed daily with indium-Ill-labeled amberlite resin and imaged throughout the day. On the fourth, the division of activity in the colon was 67% in the proximal half and 33% in the distal half day for the control subjects, whereas for the patients with colitis the distribution was 90 10. These data emphasize the problem of treating left-sided colitis effectively during active periods of disease. 

A small piece of Na was added to MeOH (5 mL) and the resulting solution was added to tetra-O-acetyl-a-D-glucopyranosyl fluoride (130 mg, 0.37 mmol) and 4,6-di-6>-acetyl-2-deoxy-2-fluoro-3-0-(tetra-6>-acetyl-/3-D-glucopyranosyl)-/ -D-glucosyl fluoride (44 mg, 0.07 mmol) in MeOH (5 mL) and the solution stirred (1 h) before being neutralized with Amberlite resin IR-120 (H+), fdtered and concentrated to afford a colourless residue. 

The reaction of a -halocarboxylic acids with sodium nitrite has been used to synthesize ni-tromethane, nitroethane and nitropropane, although the reaction fails for higher nitroalkanes. " A number of other reactions have been reported which use nitrite anion as a nucleophile, including (1) reaction of alkyl halides with potassium nitrite in the presence of 18-crown-6, (2) reaction of alkyl halides with nitrite anion bound to amberlite resins, (3) synthesis of 2-nitroethanol from the acid-catalyzed ring opening of ethylene oxide with sodium nitrite, and (4) reaction of primary alkyl chlorides with sodium nitrite in the presence of sodium iodide. ... 

According to information supphed by the vendor in 1997, a minimum order of 400 of Amberlite resin would cost 530/ft (personal communication Barbara Kinch, Rohm and Haas Company, January, 1997). 

These PVP polymers provide a "proximal effect" without addition of free pyridine in the reaction mixture. Different studies have shown that only one pyridine per manganese catalyst is sufficient to enhance the rate of the catalytic oxygen atom transfer from the high-valent metal-oxo species to the organic substrate. The advantage of PVP polymer over a cationic Amberlite resin (see Scheme II for structures) have been recently illustrated in the modeling of ligninase (11). 

The final answer came from the atomic pile. J. A. Marinsky, L. E. Glendenin, and C. D. Coryell at the Clinton Laboratories at Oak Ridge (20) obtained a mixture of fission products of uranium which contained isotopes of yttrium and the entire group of rare earths from lanthanum through europium. Using a method of ion-exchange on Amberlite resin worked out by E. R. Tompkins, J. X. Khym, and W. E. Cohn (21) they were able to obtain a mixture of praseodymium, neodymium, and element 61, and to separate the latter by fractional elution from the Amberlite column with 5 per cent ammonium citrate at pH 2.75. Neutron irradiation of neodymium also produced 61. 

In some instances, combinations of Cig and silica columns are also used for better purification of the crude extracts (431, 445). A combination of Cg, silica, and amino solid-phase extraction columns has been successfully employed to fractionate anabolic and catabolic steroid hormone residues from meat in polar and nonpolar neutral and phenolic compounds, and to purify further each fraction effectively (452). Another combination of two solid-phase extraction columns, one using a graphitized carbon black sorbent and the other Amberlite resin in the hydroxyl form, allowed neutral anabolics to be isolated and separated from acidic anabolics and their metabolites (453). A combination of basic alumina column placed in tandem with an ion-exchange column has also been applied for the purification of the crude extracts in the determination of diethylstilbestrol and zeranol (427), and estradiol and zeranol in tissues (450). 

Adsorbents. Macroreticular Amberlite resins XAD-2 and XAD-4 (20-50 mesh Lots 90721 and 89829, respectively) were obtained from BDH Chemicals Ltd. Polyurethane foam (upholstery grade, Woodbridge Foam Co.) and vegetable charcoal (Darco G-60 Lot 363-53 Matheson Canada Ltd.) were purchased. 

Further analyses of representative extracts of each of the Amberlite resins employing GC-MS indicated the presence of significant concentrations of a variety of aromatic hydrocarbons, including alkylated derivatives of benzene, styrene, naphthalene, and biphenyl. A more comprehensive listing of these contaminants, including their approximate concentrations in the sorbent matrix, is provided in Table I. 

Ambersorb Resins. Chromatographable residues attributable to each of the Ambersorb resins, XE-340 and XE-348, as shown in Figure 1, are significantly lower than the values reported for each of the Amberlite resins. As shown in Figure 3, the majority of the components isolated from the Ambersorb XE-340 resin are readily classified as polycyclic aromatic hydrocarbons. (These are believed to be associated... 

Figure 1. Cross section of sampling cartridge 1, stainless steel swagelok nut, 0.64 cm ( 4 in.), no. SS-402-1 2, stainless steel swagelok male connector, 0.95 cm (fIn.), NPT no. SS-400-1-6 3, Teflon O-ring, 2.664 cm i.d., wall thickness 0.262 cm 4, stainless steel screen, 40 mesh 5, stainless steel swagelok cap (modified with female in. NPT through end), no. SS-2400-C 6, Pyrex brand glass wool 7, XAD-2 Amberlite resin and 8, 304 stainless steel tube, 3.81 X 0.305 cm (1.5 X 0.120 in.), ASTM A269.

The silicic acid used for column chromatography and the Amberlite resin were Silicar CC-7 100-200 mesh purchased from Mallinckrodt Chemical Works, St. Louis, Mo. The 5% palladium on charcoal catalyst was purchased from Engelhard Industries Ltd., Newark, N. J. The tri-O-acetyl-D-glucal and the tri-O-acetyl-D-galactal (as a 70% solution in benzene) were purchased from Raylo Chemicals Limited, Edmonton, Alberta. 

A method for the determination of 15 BAs in different foodstuffs, namely, Swiss cheese, salami, milk, beer, and wine, was developed by Petridis and Steinhart it is based on an automated precolumn derivatization of BAs [after acidification with TCA and solid-phase extraction (SPE) on Amberlite resin] with OPA/ME and separation on a Spherisorb ODS-2 column with gradient elution (ACN-MeOH-phosphate buffer) and fluorescence detection (71). 

The final step to achieve (-)-swansonine from the indolizidine 11 required oxidation of the alkene, which proved to be surprisingly nontrivial. A procedure to carry out this transformation using 0s04, NMO, acetone and water at room temperature has been reported to give good selectivity (88 12) in favour of the desired configuration. In the case of the oxidation of 11, after desilylation and triacetate protection almost no diastereoselectivity was observed (12-13 = 50 50-42 58). An alternative method was implemented which required AD-mix-alpha,22 which improved the diastereoselectivity of 12 13 to (20 1). Final hydrolysis of 12 using Amberlite resin yielded the desired product. 

Benzylsulfanyl-5-phenyl-[l,2,4]triazol-4-ylmethyl)-benzamide (33). A solution of 4-(3-mercapto-5-phenyl-[l,2,4]triazol-4-ylmethyl)-ben-zamide (32, 0.1 mmol) in THF (6 ml) was treated with Amberlite resin (OH form, 0.1 mmol OH ) and benzyl bromide (0.15 mmol). The resulting mixture was shaken at room temperature until complete consumption... 

Ethoxalylmethylpyridine-3-carbonitrile (19) underwent cyclization to ethyl 1-oxo-1,2-dihydro-2,7-naphthyridine-3-carboxylate (20) (an Amberlite resin, H20, EtOH, reflux 10%) 986... 

As common examples of monomers used for the production of resins, methacrylate and styrene can be mentioned, where the cross-linkers are ethylene dimethacrylate (EDMA) or divinyl benzene (DVB), respectively [205], The most important resins of this type are the poly(styrene-divinyl benzene) type or Amberlite resins, as well as the Wofatit and Lewatit [192] types. These materials have been widely applied as adsorbents [191,192,207] and as ion exchangers [193,194,208],... 

Bills et al. (1963) used pre-treated Amberlite resin dispersed in hexane to isolate FFAs from milk. Fat was removed from the resin using hexane, absolute ethanol and methanol and the FFAs were esterified prior to analysis by GC. Needs et al. (1983) extracted lipids from milk by using ether and the FFAs were isolated using a strong basic anion exchange resin (Amberlyst 26, BDH Ltd, Poole Dorset, UK). The FFAs were methylated and resolved by GC. McNeill et al. (1986) also used Amberlyst resin to isolate FFAs in conjunction with silicic acid to remove phospholipids. Extracted FFAs were then analyzed by GC. This method was used by McNeill and Connolly (1989) to quantify FFAs in a number of semi-hard cheeses. 

At the end of the period return the Dowex to the container provided by your instructor. (NOTE Do not allow the Dowex to become mixed with the Amberlite resin used in Day 3.)... 

Oliver [190] recommends the dissolution of the polymer if possible (see above) but in other cases a wet ashing procedure was used. The sample was heated with 2—3 ml of concentrated sulphuric acid and then hydrogen peroxide added drop-wise until the organic matter was destroyed. Twenty elements were determined in a 2% solution of polymer. Polymers may be dispersed in an organic solvent and trace metals removed by leaching with an appropriate aqueous solution, preferably the procedure should be repeated more than once to ensure complete extraction. To determine antimony in fire-retardant polypropylene, the sample was dispersed in xylene and extracted with 6M hydrochloric acid under reflux [191]. The filtered acid layer was combined with two further extracts prior to aspiration into the air/acetylene flame and measurement at 217.6 nm. Martinie and Schilt [45] reported that nylon would dissolve completely in perchloric/nitric acid digestion but potentially explosive problems were encountered in the dissolution of Amberlite resins and rubber. 

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