Tetrabutylammonium cation

A comprehensive study of the complex interfacial processes involved in the solvent extraction of cupric ion by oxime ligands represents one of the most detailed and successful studies carried out with the RDC [37,38]. Recently, the technique was also used to study the transfer of tetrabutylammonium cations [43] and the kinetics of partitioning of compounds between octanol and water [44]. In the latter study, Fisk and coworkers investigated the rates of partitioning of 23 compounds from octanol to an aqueous phase. The RDC arrangement used most frequently in this work is of the o/o/w type. So according to Eq. (15), and can be calculated from the gradient and intercept of... 

The sodium cation chelation by the bis(enone) anion-radicals shown in Scheme 3.52 controls their further transformations although they proceed at the expense of other reaction centers (Yang et al. 2004). This kind of intramolecular cyclobutanation is characterized with the pronounced cis-stereoselectivity. However, this stereoselectivity disappears if the reaction proceeds in the presence of the tetrabutylammonium cation, when such a chelation is impossible. 

Most investigations on edl of zinc singlecrystal faces were made in solutions containing organic compounds tetraethy-lammonium cations [7], hexanol [17-19], tetrabutylammonium cations [13, 14, 18, 19], camphor [18-20], cyclohexanol [14, 21], andTU [22, 23]. For these substances, dependence of adsorption properties on... 

The Ru dye photosensitizer, which contributes the primary steps of photon absorption and the consequent electron injection, is fixed onto the Ti02 surface. The chemical structures of typical Ru dye photosensitizers developed by Gratzel and co-workers are shown in Fig. 4. TBA denotes the tetrabutylammonium cation... 

Increased retention of the analytes can also be achieved by addition of various ion-pair reagents in the mobile phase Tetrabutylammonium cations have typically been used as counter ions, at around pH 6.5, to increase retention and improve the selectivity in the analysis of monobasic penicillins (105, 123). Alkyl-sulfonic acids have been also used to improve the separation of -lactams bearing an amine function in their side chain or having a neutral side chain. Heptanesul-fonic acid (80, 103), decanesulfonic acid (87, 93, 106), dodecanesulfonic acid (77, 107-110), or mixtures of octanesulfonic and dodecanesulfonic acids (73, 75, 78, 79) constitute the principal alkylsulfonic acids used in -lactam analysis. In some applications, heptafluorobutyric acid (74, 76) or sodium thiosulfate (90, 112, 115, 116, 121, 122) has also been used as an ion-pairing reagent. 

The origin of the majority of rhenium—rhenium quadruple bonds can be traced directly to the parent Re2Clg anion. Several routes to the octachloro-dirhenate(III) ionic complex have been compared (42). The method of choice is the reaction of trirhenium nonachloride with molten diethylammonium chloride (12). Yields of up to 65% are attainable when the reaction mixture is extracted with hydrochloric acid and the anion is precipitated as the salt of a large cation (i.e., tetrabutylammonium cation). 

Table I. Organic compounds, which were mostly used in syntheses of zeolites of pentasil-type. Abbreviations are TPA for te-trapropylammonium cation, TEPA for trie thy lmonopropy lam-monium cation, TBA for tetrabutylammonium cation, TBP for tetrabutylphosphonium cation, TPA for tripropylamine and C DN for hexamethyldiamine...

The media represented in Table 10 contain, as a rule, a protic component but in small amounts. However, the content of proton donors can be increased appreciably hydrogenation of benzene can be effected in mixtures of water and aptotic solvents (such as diglyme, ethylenediamine, sulfolan. Table 11). Furthermore, benzene can be reduced not only in a mixture of aptotic and protic solvents but often in protic media as well. Mono- and dibasic alcohols and also water (Table 11) proved to be suitable for the purpose. Although the presence of tetrabutylammonium cations enhances to some extent the dissolution of benzene in an aqueous phase. 

In order to achieve an opposite elution order, having the basic fractions before the acidic fractions (Fig. 12.16), a neutral salt composed of large tetrabutylammonium cations and small iodide anions (9.88 and 6.62 A, respectively) was injected. In this case a typical hypercrossHnked polystyrene material, Styrosorb 2, which is known to have only small nanopores, was used as the sorbent. Indeed, as expected, the large organic cations were totally excluded from the polymer phase, while the smaller... 

Actually, size exclusion should not be the only possible separation mechanism resulting in a spontaneous chromatographic salt resolution. Any type of differentiated retention of the cation or anion must also generate acidic and basic effluent zones. Thus, in the case of ammonium acetate, simple dispersive (hydrophobic) interactions of the acetate anions overbalance their partial exclusion from the Styrosorb 2 polymer phase. Here, the ammonia-enriched alkafrne firactions elute first, while the acetic acid-smelling acidic fractions elute from the column with a pronounced retention (Fig. 12.17). It should be noted that contrary to the bulky tetrabutylammonium cations, the acetate anions are barely excluded from the polymer phase and can experience hydrophobic retention in fine pores. 

Acidic buffers Tetraalkylammonium and tetrabutylammonium cations Peptides and proteins Quang et al. (2003)... 

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