Tetrabutyl ammonium salts

It is shown that both Sb(III) and Bi(III) can speed reduction of 12-molybdophosphate (12-MPC) to the corresponding heteropoly blue (12-MPB) by ascorbic acid (AA). It is found that mixed polyoxometalates can be formed in solution which reduce considerably more rapidly than 12-MPC. Complete formation of mixed POM is observed only if significant excess of Me(III) ions is used in the reaction. POM responsible for blue color was synthesized by selective extraction. Chemical analysis of tetrabutyl-ammonium salt is in accordance with formula of (TBAl PMeflllfMo O j (Me = Sb, Bi). IR spectmm of mixed POM is identical to 12-MPC. 

The peak capacity is not pertinent as the separation was developed by a solvent program. The expected efficiency of the column when operated at the optimum velocity would be about 5,500 theoretical plates. This is not a particularly high efficiency and so the separation depended heavily on the phases selected and the gradient employed. The separation was achieved by a complex mixture of ionic and dispersive interactions between the solutes and the stationary phase and ionic, polar and dispersive forces between the solutes and the mobile phase. The initial solvent was a 1% acetic acid and 1 mM tetrabutyl ammonium phosphate buffered to a pH of 2.8. Initially the tetrabutyl ammonium salt would be adsorbed strongly on the reverse phase and thus acted as an adsorbed ion exchanger. During the program, acetonitrile was added to the solvent and initially this increased the dispersive interactions between the solute and the mobile phase. 

As the acetonitrile concentration increased, however, the concentration of adsorbed tetrabutyl ammonium salt would also be reduced and it would be desorbed from the reverse phase with a resulting reduction in the ionic interactions of the solutes with the stationary phase. At higher concentrations of acetonitrile, the tetrabutyl ammonium salt would be completely desorbed from the stationary phase and the interactions of the solutes with the stationary phase would become almost exclusively dispersive. This is an example... 

Tetrachlorooxotechnetate(V) results from action of cone. HC1 on perteeh-netate at ambient temperatures and is preferably isolated as the tetrabutyl-ammonium salt [19]. Tetrabromooxotechnetate(V) was similarly obtained with hydrobromic add at 0 °C [8]. The molecular structures of both compounds are reported in [20,21]. The analogous iodo complex, tetraiodooxotechnetate(V), was synthesized by ligand exchange of the chloro compound with sodium iodide in acetone [22]. However, it suffers from considerable decomposition during isolation. 

Obtained in acetonitrile solution containing 0.2 mol dm-3 Bu NBF4 as supporting electrolyte. Solutions were 1 x 10 3 mol dm-3 in receptor and potentials were determined with reference to an Ag/Ag+ electrode. Two-electron process. Four-electron process. Cathodic shift in redox wave produced by the presence of anions (up to 5.0 equiv) added as their tetrabutyl-ammonium salts. 

Refer to footnote a Table 23. h pa and pc represent the anodic and cathodic current peak potentials of the ferrocene/ferrocenium redox couple of the free ligand. Cathodic shifts in the ferrocene redox couples produced by the presence of anion (5 equiv) added as the tetrabutyl-ammonium salts. As the concentration of the anion increased, the ferrocene/ferrocenium redox couple began to exhibit the features of an EC mechanism. 

One of the first compounds to be introduced to the clinic, aztreonam (40-9), has been produced by total synthesis. Constmction of the chiral azetidone starts with amide formation of L-threonine (40-1) via its acid chloride treatment with ammonia leads to the corresponding amide (40-2). The primary amino group in that product is then protected as its carbobenzyloxy derivative (40-3). Reaction of that product with methanesulfonyl chloride affords the mesylate (40-4). Treatment of that intermediate with the pyridine sulfur trioxide complex leads to the formation of the A -sulfonated amide (40-5). Potassium bicarbonate is sufficiently basic to ionize the very acidic proton on the amide the resulting anion then displaces the adjacent mesylate to form the desired azetidone the product is isolated as its tetrabutyl ammonium salt (40-6). Catalytic hydrogenation over palladium removes the carbobenzyloxy protecting group to afford the free primary amine (40-7). The... 

The classic sensitizer dye employed in DSC is a Ru(II) bipyridyl dye, cis-bis(isothiocyanato)-bis(2,2/-bipyridyl-4,4/-dicarboxylato)-Ru(II), often referred to as N3 , or in its partially deprotonated form (a di-tetrabutyl-ammonium salt) as N719. The structure of these dyes are shown in 2 and 26. The incorporation of carboxylate groups allows immobilization of sensitizer to the film surface via the formation of bidendate coordination and ester linkages, whilst the (- NCS) groups enhance the visible light absorption. Adsorption of the dye to the mesoporous film is achieved by simple immersion of the film in a solution of dye, which results in the adsorption of a dye monolayer to the film surface. The counter electrode is fabricated from FTO-coated glass, with the addition of a Pt catalyst to catalyze the reduc-... 

Since the phosphate anion is resonance stabilised, nucleophilic substitution of the bromine atom of the coumarin derivative can occur by either of the two free oxygen atoms. Thus two diastereomers will be produced, which may be distinguished between merely by considering the configuration at the phosphorus atom. In a publication it was shown that using the tetrabutyl-ammonium salt of cyclic AMP (cAMP) in acetonitrile the diastereoisomeric ratio was 85 15 in favour of the compound with an S-configured phosphorus atom [10]. 

Figures 12 and 13 present a pair of similar spectra from similar measurements and an experimental setup obtained from Li electrodes aged in EC and DMC solutions, respectively. Figures 14 and 15 show reference FTIR spectra of the electrolysis products of PC and EC, respectively, in tetrabutyl ammonium salt solutions, isolated as Li salts. The spectra in Figures 14 and 15 are typical of R0C02Li species [188], The relevant compounds were identified as...

N-Alkylation of 1,2,3-triazoles and benzotriazoles is readily achieved using (1) alkyl halides, dialkyl sulfates, diazoalkanes, and jS-tosylates or (2) the Mannich reaction. When alkyl halides are used, sodium alkoxide, sodium hydride, or sodium hydroxide is usually employed as the base. The N-alkylation of benzotriazole with alkyl halides proceeds efficiently using powdered NaOH as the base in DMF. The highest yields (80100%) of the alkylated benzotriazoles are obtained when a fourfold excess of NaOFl is employed. A-Alkylbenzotriazoles have been prepared from benzotriazole and alkyl halides using phase-transfer catalysts, e.g., KOFI, benzene, tetrabutyl-ammonium salts or KOH, benzene, polyethylene glycol. 

Watanabe, Y., and T. Mukiyama, A Convenient Method for the Synthesis of Carboxamides and Peptides by the Use of Tetrabutyl Ammonium Salts, Chem. Lett., 285 (1981a). 

A final method to induce living polymerization of vinyl ethers is based on halide exchange reactions by the addition of a salt. The addition of a tetrabutyl ammonium salt with a nonnucleophilic counteranion, such as perchlorate, to an a-halide ether results in an exchange equilibrium between the halide and the perchlorate. The formed perchlorate adduct is also in equilibrium with the carbocationic species inducing living polymerization of various vinyl ethers as depicted in Scheme 8.12 [53-55]... 

The acid is dissolved in methanol and titrated with 24% tetramethylammonium hydroxide in methanol to phenol-phthalein. The sample (1-5 /A) is injected for gas chromatography with a flash heater, loosely packed with glass wool, at a temperature of 350 °C [122]. A similar procedure, but with the trimethylammonium salt of the acid made first in a capiUary probe, and the probe then quickly inserted into the heated inlet zone of the gas chromatograph, is claimed to give a higher yield [124], For the volatile formic and for lactic acid, the tetrabutyl-ammonium salts were made instead and pyrolysed in the same way [125]. 

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