Amine oxides exchange

As with arene-amine radical ion pairs, the ion pairs formed between ketones and amines can also suffer a-deprotona-tion. When triplet benzophenone is intercepted by amino acids, the aminium cation radical can be detected at acidic pH, but only the radical formed by aminium deprotonation is detectable in base (178). In the interaction of thioxanthone with trialky lamines, the triplet quenching rate constant correlates with amine oxidation potential, implicating rate determining radical ion pair formation which can also be observed spectroscopically. That the efficiency of electron exchange controls the overall reaction efficiency is consistent with the absence of an appreciable isotope effect when t-butylamine is used as an electron donor (179). 

Farnum, M., Palcic, M., and Klinman, J. P., 1986, pH dependence of deuterium isotope effects and tritium exchange in the bovine plasma amine oxidase reaction a role for single base catalysis in amine oxidation and imine exchange. Biochemistry, 25 1898n 1904. 

Reductive desulfurization of the dithioketals 5.14 and 5.15 is performed under the same conditions as for thioethers [G02] LAH in the presence of copper salts or borohydrides in the presence of nickel salts (Figure 5.8). The deoxygenation of tertiary amine-oxides such as 5.16 and 5.17 can be performed with borohydride exchange resin-copper sulfate in methanol at room temperature or under reflux. This reaction tolerates other functional groups such as carbon-carbon double bonds, chlorides, epoxides, esters, amides, nitriles, sulfoxides, and sulfones [SA4] (Figure 5.8). 

The exchange of amine oxides has not yet been examined. Nitromethane (Gragerov and Levit, 1960) and nitrobenzene (Roberts, 1938 Gragerov and Levit, 1960) do not undergo exchange even under very drastic conditions. It should be recalled that exchange with the nitrate ion only occurs in strong acid solution by the reversible formation of a nitronium cation [N02]+ (Bunton et al., 1952). This mechanism cannot occur in... 

Betaines (WS), however, are not retained by the anion exchanger. If a betaine and/or weak bases (amines or amine oxides) are present, use a three-column system, as follows. 

Column 2 strongly basic anion exchanger hydroxide. Retains carboxy-lates and WW and SW amphoterics. Elute with hydrochloric acid. Car boxy lates and amphoterics are eluted rapidly. Response of phosphate esters is uncertain, but if they were not retained by column 1 they would be retained by column 2 and also eluted rapidly. Quaternary salts are converted to the hydroxide, weakly basic cationics (amines, amine oxides) to the free base and betaines to the zwitterionic form. All of these pass through. 

As in previous chapters, this chapter deals with the analysis of cationics and amphoterics either alone, as raw materials or as fractions isolated by ion exchange or otherwise, or in formulated products. Fractions isolated by ion exchange are likely to contain other materials, analogously with anionics. Amines, ethoxylated amines and amine oxides are included in this chapter because they are bases and capable of a cationic function. They are retained as cations by ion-exchange columns and do not appear in the nonionic fraction of separated mixtures, they can be titrated with acids and, in acid solution, with sodium dodecyl sulphate, provided the ethylene oxide chains of ethoxylates are not too long. 

Solvent recovery consists of two main processes, ion exchange of the dilute solvent then evaporation of the excess water to a concentration required in premixing. The ion exchange process consists of cation and anion beds which remove various ions that would destabilise the solution and the colour contaminants that would otherwise build up in the solvent. The ion exchange resins and regeneration procedures have been developed especially for amine oxide. 

Amine oxide from other surfactants Dowex 50W-X4 strongly acidic cation exchange resin, acid form Surfactant mixture is dissolved in 50 50 Et0H/H20 and passed through the column, washing with 300 mL EtOH/H20. The amine oxide behaves as a cationic under acid conditions and remains on the column. The amine oxide is then eluted with 300 mL 1 M ethanolic HCl solution. 109... 

Zirconium tetrachloride is instantly hydrolyzed in water to zirconium oxide dichloride octahydrate [13520-92-8]. Zirconium tetrachloride exchanges chlorine for 0x0 bonds in the reaction with hydroxylic ligands, forming alkoxides from alcohols (see Alkoxides, METAl). Zirconium tetrachloride combines with many Lewis bases such as dimethyl sulfoxide, phosphoms oxychloride and amines including ammonia, ethers, and ketones. The zirconium organometalLic compounds ate all derived from zirconium tetrachloride. 

Pyridine, 3-(dimethylamino)-amination, 2, 236 methylation, 2, 342 nitration, 2, 192 iV-oxide synthesis, 2, 342 Pyridine, 4-(dimethylamino)-in acylation, 2, 180 alkyl derivatives pK, 2, 171 amination, 2, 234 Arrhenius parameters, 2, 172 as base catalysts, 1, 475 hydrogen-deuterium exchange, 2, 286 ionization constants, 2, 172 methylation, 2, 342 nitration, 2, 192 iV-oxide synthesis, 2, 342... 

Purely parallel reactions are e.g. competitive reactions which are frequently carried out purposefully, with the aim of estimating relative reactivities of reactants these will be discussed elsewhere (Section IV.E). Several kinetic studies have been made of noncompetitive parallel reactions. The examples may be parallel formation of benzene and methylcyclo-pentane by simultaneous dehydrogenation and isomerization of cyclohexane on rhenium-paladium or on platinum catalysts on suitable supports (88, 89), parallel formation of mesityl oxide, acetone, and phorone from diacetone alcohol on an acidic ion exchanger (41), disproportionation of amines on alumina, accompanied by olefin-forming elimination (20), dehydrogenation of butane coupled with hydrogenation of ethylene or propylene on a chromia-alumina catalyst (24), or parallel formation of ethyl-, methylethyl-, and vinylethylbenzene from diethylbenzene on faujasite (89a). 

Also, the CL aqueous solution may be hydrogenated at 60°C in the presence of 20% sodium hydroxide and 50% palladium absorbed on carbon to provide caprolactam of very high purity after distillation. Treatment with an ion exchange resin before or after the oxidation or hydrogenation process also improves the quality of the CL obtained after distillation. CL has also been purified by treatment with alkali and formaldehyde followed by fractional distillation to remove aromatic amines and other products. 

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