Basic ion exchanger

The reactions are catalyzed by tertiary amines, quaternary ammonium salts, metal salts, and basic ion-exchange resins. The products are difficult to purify and generally contain low concentrations of acryhc acid and some diester which should be kept to a minimum since its presence leads to product instabihty and to polymer cross-linking. 

The peroxycarboxyhc acid can be generated m situ by autoxidation of aldehydes, either in the presence of anhydrides or an acyl chloride and a base, eg, sodium carbonate, or basic ion-exchange resins (44,187,188,210) ... 

Methyl formate and propylene oxide have close boiling poiats, making separation by distillation difficult. Methyl formate is removed from propylene oxide by hydrolysis with an aqueous base and glycerol, followed by phase separation and distillation (152,153). Methyl formate may be hydrolyzed to methanol and formic acid by contacting the propylene oxide stream with a basic ion-exchange resia. Methanol and formic acid are removed by extractive distillation (154). 

Acetone cyanohydrin is used as a raw material for insecticides manufacture and also to produce ethyl a-hydroxyisobutryate [80-55-7], a pharmaceutical intermediate. It has been used as a complexing agent for metals refining and separation. Acetone cyanohydrin complexes can be used to separate, Cu , , 7x5, Cd , or Fe from Mg , , Ca , Na , or on strongly basic ion-exchange resins (31). Acetone cyanohydrin is... 

Base catalysis is most effective with alkali metals dispersed on solid supports or, in the homogeneous form, as aldoxides, amides, and so on. Small amounts of promoters form organoalkali comnpounds that really contribute the catalytic power. Basic ion exchange resins also are usebil. Base-catalyzed processes include isomerization and oligomerization of olefins, reactions of olefins with aromatics, and hydrogenation of polynuclear aromatics. 

To a solution of 5 g of sisomicin in 250 ml of water add 1 N sulfuric acid until the pH of the solution is adjusted to about 5. To the solution of sisomicin sulfuric acid addition salt thereby formed, add 2 ml of acetaldehyde, stir for 10 minutes, then add 0.B5 g of sodium cyanoborohydride. Continue stirring at room temperature for 15 minutes, then concentrate solution In vacuo to a volume of about 100 ml, treat the solution with a basic ion exchange resin [e.g., Amberlite IRA401S (OH )], then lyophilize to a residue comprising 1-N-ethyl-sisomicin. 

These resins are similar to the sulphonate cation exchange resins in their activity, and their action is largely independent of pH. Weakly basic ion exchange resins contain little of the hydroxide form in basic solution. The equilibrium of, say,... 

Benzodiazepine 4-oxide 1 rearranges to the 1,5-diazocine 5-oxide 2 upon treatment with base sodium hydroxide, ammonia or a basic ion-exchange resin can be employed.53 - 56... 

Silica gel supported sodium metaperiodate was used for the selective oxidation of dibenzyl sulphide80. Metaperiodate anion soaked on strongly basic-ion-exchange resins Amberlite IRA-904 or Amberlyst A-26 was found to be able to oxidize sulphides into the corresponding sulphoxides in 82-99% yield81. 

As the solvent mixture also contained 225 mg of tetramethyl ammonium hydroxide pentahydrate per liter at a high water content (75%), the surface of the reverse phase would have been largely covered with the tetramethyl ammonium hydroxide pentahydrate. This would have acted as an adsorbed ion exchange stationary phase. It is clear that the free acids, salicylic acid, acetylsalicylic acid (aspirin) and benzoic acid were retained largely by ionic interactions with adsorbed basic ion exchanger and partly by dispersive interactions with the exposed reversed phase. The acetaminophen and the caffeine, on the other hand, being unionized substances, were retained only by dispersive interactions with the exposed reversed phase. 

Reaction between Two Molecules of the Same Aldehyde. The equilibrium lies far to the right, and the reaction is quite feasible. Many aldehydes have been converted to aldols and/or their dehydration products in this manner. The most effective catalysts are basic ion-exchange resins. Of course, the aldehyde must possess an a hydrogen. 

Chloroform extraction of uranium quinoline complex Uranium adsorbed as azide on basic ion exchange column, uranium desorbed with 1 M hydrochloric acid Uranium adsorbed on bismuthol(II) modified anion exchange resin, desorbed with 0.1 M cysteine Uranium, by square wave adsorptive stripping voltammetry... 

OH—on the adjacent (/ -) carbon atom. The possibility of such an elimination may displace the equilibrium over to the right in a number of simple aldol additions, where it would otherwise lie far over to the left. It is important to remember, however, that the overall process aldol addition + dehydration is reversible, i.e. (88) 4= (96), and that a -unsaturaled carbonyl compounds are thus cleaved by base under suitable conditions. It is also pertinent that (96) is still an aldehyde and can undergo further carbanion addition, followed by dehydration, and so on. This is how low molecular weight polymers are produced on heating simple aliphatic aldehydes with aqueous NaOH to stop at the aldol, the best catalysts are basic ion-exchange resins. 

The conversion of the quaternary ammonium iodide to the hydroxide may also be carried out using a strongly basic ion exchange resin. ... 

In a similar way, many acidic and basic ion-exchange polymers have been used to quench and work-up reactions as an alternative to aqueous conditions. This is especially valuable if the compound in question is moisture sensitive or hydroscopic, or if a rapid quench and work-up procedure is required. 

Other attempts at using such combinations include preconcentration of elements by using basic ion-exchange principles. Two methods of development are described here firstly, the work by Bysouth et al. [26—28] and secondly that of Gunther Knapp at the University of Graz. TTiese are now available commercially from Dionex, and from Knapp Logistics. 

Hydroxyurea Hydroxyurea (30.6.1) is made by reacting sodium cyanate with hydroxyl-amine. In this reaction, hydroxylamine hydrochloride and a basic ion-exchange resin are used [140,141],... 

Aqueous base (e.g., NaOH or basic ion-exchange resin) has been used for Aldol reactions. In this case, the performance of the ionic liquids containing 1 mol% NaOH was compared with that of water with the same NaOH content. In the Aldol... 

In the method proposed by van Staden for the determination of three halides, these are separated in a short colunm packed with a strongly basic ion-exchange resin (Dowex i-X8) that is placed in an FI manifold. A laboratory-made tubular silver/silver halide ion-selective electrode is used as a potentiometric sensor. Van Staden compared the response capabilities of the halide-selective electrodes to a wide concentration range (20-5000 pg/mL) of individual and mixed halide solutions in the presence and absence of the ion-exchange column. By careful selection of appropriate concentrations of the potassixun nitrate carrier/eluent stream to satisfy the requirements of both the ion-exchange column and the halide-selective electrode, he succeeded in separating and determining chloride, bromide and iodide in mixed halide solutions with a detection limit of 5 /xg/mL [130]. 

Addition of nucleophiles to the cyano group of cyanothiadiazole under basic conditions takes place with unusual ease <88AG(E)434,94ACS372). Hydrolysis to the amide, for example, can be effected at 0°C in the presence of a catalytic amount of sodium hydroxide or basic ion-exchange resin. At reflux temperature, hydrazine and monosubstituted hydrazines convert 3,4-dicyano-l,2,5-thia-diazole into the l,2,5-thiadiazole[3,4-. The base-catalyzed addition of acetone to cyanothiadiazole forms an enamino ketone, used as a key intermediate for the synthesis of a number of heterocyclic ring systems, e.g. isothiazole, isoxazole, pyrazole, pyrimidine, and thiazole <77H(6)1985>. 

They are useful only in hyperlipoproteinemias involving elevated levels of LDL i.e. type Ila, lib and V. They are basic ion exchange resins. They are neither digested nor absorbed in the gut. They bind bile acids in intestine and interrupt their entero-hepatic circulation, leading to increased faecal excretion of bile salts and cholesterol. There is increased hepatic conversion of choles-terol to bile acids. More LDL receptors are expressed on liver cells leading to increased clearance of IDL, LDL and indirectly of VLDL. 

It forms a picrate m 149° (from EtOH-pet ether) from which the free base can be recovered using a basic ion exchange resin and can then be distd through a Todd column using an automatic still head which only collects products boiling below 51°/atm. Polymeric materials if present will boil above this temperature. The hydrochloride has m 85-86°. The pKa in 40% EtOH is 5.33. [Roberts and Chambers JACS 73 5030 1951, Jones JOC 9 484 7944 Emmons J A CS 79 6522 1957. ... 

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