Resins hydroxide-selective

Abbreviations Amberlite IRA 400 borohydride resin, commercially available resin for selective reduction of a,/3-unsaturated aldehydes and ketones DBU, 1,8-diazabicyclo [5.4.0]undec-7-en DCM, dichloromethane DMF, dimethylformamide EtOAc, ethyl acetate Et2NH, diethylamine Et3N, triethylamine HBr, hydrobromic acid HC1, hydrochloric acid MS, mass spectrometry MeOH, methyl alcohol NH4OH, ammonium hydroxide NaBHj, sodium borohydride NaOH, sodium hydroxide NaOMe, sodium methanolate PAMAM, polyaminoamide resin (commercially available) RT, room temperature THF, tetrahydrofuran. 

Solvents such as benzene, carbon disulfide, ether, methyl ethyl ketone, toluene, xylene, trichloroethylene, and trichloroethane will attack the resin. Sulfuric acid above 70%, sodium hydroxide, and 30% chromic acid will also attack the resin. Refer to Table 3.8 for the compatibility of bisphenol-A fumarate polyester resin with selected corrodents. Table 3.9 lists the compatibility of hydrogenated bisphenol-A fumarate polyesters with selected corrodents. Reference [1] provides a more comprehensive listing. 

Hydroxide-Selective Grafted Polymers Dionex (now part of Thermo Fisher Scientific) also introduced a hydroxide-selective, surface-functionalized EVB/DVB resin featuring a covalently attached anion-exchange polymer under the trade... 

DeioniZa.tlon, The removal of cations and anions from water and replacement of them with hydrogen and hydroxide ions is called deionization. The completeness of the ionic removal is dependent on resin selection, design of the system, operating conditions, and the quaUty of treated water required. In general, systems become more complex as quaUty requirements increase. 

In the three-step process acetone first undergoes a Uquid-phase alkah-cataly2ed condensation to form diacetone alcohol. Many alkaU metal oxides, metal hydroxides (eg, sodium, barium, potassium, magnesium, and lanthanium), and anion-exchange resins are described in the Uterature as suitable catalysts. The selectivity to diacetone alcohol is typicaUy 90—95 wt % (64). In the second step diacetone alcohol is dehydrated to mesityl oxide over an acid catalyst such as phosphoric or sulfuric acid. The reaction takes place at 95—130°C and selectivity to mesityl oxide is 80—85 wt % (64). A one-step conversion of acetone to mesityl oxide is also possible. 

Synthetic Marble. Synthetic marble-like resin products are prepared by casting or molding a highly filled monomer mixture or monomer—polymer symp. When only one smooth surface is required, a continuous casting process using only one endless stainless steel belt can be used (52,53). Typically on the order of 60 wt % inorganic filler is used. The inorganic fillers, such as aluminum hydroxide, calcium carbonate, etc, are selected on the basis of cost, and such properties as the translucence, chemical and water resistance, and ease of subsequent fabrication (54,55). 

A Friedel-Crafts-type reaction of phenols under basic conditions is also possible. Aqueous alkaline phenol-aldehyde condensation is the reaction for generating phenol-formaldehyde resin.34 The condensation of phenol with glyoxylic acid in alkaline solution by using aqueous glyoxylic acid generates 4-hydroxyphenylacetic acid. The use of tetraalkylammonium hydroxide instead of sodium hydroxide increases the para-selectivity of the condensation.35 Base-catalyzed formation of benzo[b]furano[60]- and -[70]fullerenes occurred via the reaction of C60CI6 with phenol in the presence of aqueous KOH and under nitrogen.36... 

The first fractionation of urinary ampholytes in this way was carried out by Boulanger et al. (BIO) in 1952 with the use of ion-exchange resins. They had designed this procedure previously for the fractionation of ampholytes in blood serum (B8). According to this method, deproteinized urine was subjected to a double initial procedure aiming at the separation of low-molecular weight substances from macro-molecular ones. One of the methods consisted of the fractionation of urinary constituents by means of dialysis, the second was based on the selective precipitation of urinary ampholytes with cadmium hydroxide, which, as had previously been demonstrated, permits separation of the bulk of amino acids from polypeptides precipitated under these circumstances. Three fractions, i.e., the undialyzable part of urine, the dialyzed fraction, and the so-called cadmium precipitate were analyzed subsequently. 

Materials. Epoxy novolac, DEN-431, obtained from Dow Chemical Co. was selected as the epoxy component. A 3,3 -diazidodiphenyl sulfone synthesized in our laboratory (5) was used as the azide compound. Poly(/7-vinyl phenol) obtained from Maruzen Oil Co. was used as the phenolic resin matrix. The coating solvent was cyclohexanone. The developer used in this study was 0.1 N tetramethylammonium hydroxide aqueous solution. 

The XAD-4 quaternary resin used in these studies was prepared by the Ames Laboratory in Ames, Iowa. This resin had been used in studies by the Ames group for the adsorption and selective separation of acidic material in waste waters. For this study, the resin was chosen for its effectiveness in concentrating anionic material from solution. At the same time, it was thought that sufficient sites would be available to effectively adsorb neutral organic compounds from water. The resin was basically an XAD-4 macroreticular cross-linked polystyrene into which a trimethylamine group was introduced. The resin was stored in the chloride form but was converted to the hydroxide form before use in the resin sorption experiments. 

Sample Preparation. The three primary resoles selected for inclusion in this study were synthesized in laboratory glassware in 4000 gram batches, using 99+% commercial phenol, ion-exchanged (low formic acid content) 50% aqueous formaldehyde, reagent grade 50% aqueous sodium hydroxide, and tap water. The three resins, coded A, B, and C, were allowed to react to the same apparent bulk viscosity as measured by the Gardner-Holdt bubble tube method. In addition to the same final viscosities, the resins also were synthesized from identical mole ratios F/P = 2.0, Na/P = 0.71. 

An alternative strategy towards benzimidazole synthesis relies on the palladium-catalysed cyclisation of (2-bromophenyl)amidines. This chemistry has been reported to take place under aqueous reaction conditions, in the presence of sodium hydroxide in sealed microwave vials. The products were isolated by a catch and release method using a strongly acidic ion exchange resin, thereby avoiding conventional chromatographic purification (Scheme 3.14)23. Selectively, N-functionalised benzimidazoles were conveniently prepared by this method. 

Various workers [28,34,41] have used different extraction solutions in the ion-selective electrode method, depending on the soil being analysed. The most important are [28,32,35-37] potassium sulfate [39], aluminium sulfate [30], copper (II) sulfate [32], calcium hydroxide [33], and copper sulfate(II) with aluminium and silver resins [41 ]. 

Borate is selectively concentrated on Amberlite XE-243 ion exchange resin and converted to tetrafluoroborate using 10% hydrofluoric acid. Tetrafluoroborate is strongly retained by the resin, thus allowing excess fluoride to be eluted without loss of boron. The tetrafluoroborate is eluted with lmol L 1 sodium hydroxide and is determined in the eluent by ion chromatography. Boron is quantified to a lower limit of 0.05mg L 1. 

But let us return to conventional IEC and consider the order of anion selectivities. It can be seen that an anion resin in the citrate form would be useless—citrate is the anion most strongly held, and it would not be appreciably displaced by any other anion in the list. To convert a citrate or sulfate resin to another form requires extensive washing with a mobile phase highly concentrated in the other ion in order to effect the displacement equilibrium. It is even difficult to convert completely a chloride resin to its hydroxide form. Thus, in purchasing a resin, it is important to note the counterion with which it is sold. Commonly anion resins are in the chloride form and cation resins in the hydrogen form. 

Chemistry, Physics, and Biology Laboratories. As a rule, before any artifact is subjected to treatment, the chemistry laboratory determines the causes of any alterations or deterioration. The nature and structure of the artifact, its pigments and inks, are identified to avoid negative reactions to prescribed treatment. Fixatives are recommended if required these may be cellulose acetate dissolved in acetone, soluble nylon, or acrylic resin sprays. Once stains are identified, several possible solvents are selected. For deacidification, either magnesium bicarbonate or barium hydroxide usually is recommended, depending on whether an aqueous or nonaqueous solution is called for. Bleaching is discouraged, but when necessary, hypochlorites are used with suitable antichlors. 

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