Alkylammonium ion

The direction of electroosmotic flow and, therefore, the order of elution in CZE can be reversed. This is accomplished by adding an alkylammonium salt to the buffer solution. As shown in Figure 12.45, the positively charged end of the alkylammonium ion binds to the negatively charged silanate ions on the capillary s walls. The alkylammonium ion s tail is hydrophobic and associates with the tail of another alkylammonium ion. The result is a layer of positive charges to which anions in the buffer solution are attracted. The migration of these solvated anions toward... 

Foreign cations can increasingly lower the yield in the order Fe, Co " < Ca " < Mn < Pb " [22]. This is possibly due to the formation of oxide layers at the anode [42], Alkali and alkaline earth metal ions, alkylammonium ions and also zinc or nickel cations do not effect the Kolbe reaction [40] and are therefore the counterions of choice in preparative applications. Methanol is the best suited solvent for Kolbe electrolysis [7, 43]. Its oxidation is extensively inhibited by the formation of the carboxylate layer. The following electrolytes with methanol as solvent have been used MeOH-sodium carboxylate [44], MeOH—MeONa [45, 46], MeOH—NaOH [47], MeOH—EtsN-pyridine [48]. The yield of the Kolbe dimer decreases in media that contain more than 4% water. 

FIG. 3 Orientations of alkylammonium ions in the galleries of clay layers with different layer charge densities. (From Ref. 28.)... 

Recently, the abilities of primary to tertiary alkylammonium ions with Me, Et, and -Bu groups to transport water to NB have been studied [48]. As the result of careful consideration of the ion-pair formation, it has been shown that the hydration numbers (w ) of the ammonium ions in NB, being little affected by the alkyl chain length, are simply dependent on the class of the ammonium ion % = 1.64, 1.04, 0.66, respectively, for the primary, secondary, and tertiary ammonium ions. 

Gross et al. [3] and Reid et al. [30] measured surface tension of the water-nitrobenzene interface in the presence of bromides of sodium and tetra-alkylammonium ions in water and tetra-alkylammonium tetraphenylborates in nitrobenzene, i.e., tetra-alkylammonium served as the potential-determining ion, cf. the scheme (13). The surface tension vs. the potential difference A p plot (electrocapillary curve), cf. Eq. (15), was constructed by varying the concentration of tetra-alkylammonium bromide in water, while holding... 

TABLE 1 Tetra-alkylammonium Ion, R4N, Transferred from W to DCE by the Coupling with the Redox Reaction Between NADH in W and a Quinone Derivative in DCE. Results After Shaking W Containing 10 M NADH and 10 M (R4N )2 SO4 with DCE Containing 10 M Quinone [Q Chloranil (CQ) or Toluquinone (TQ)] for 1 h. TPenA, TBA, and TEA Denote Tetrapentylammonium, Tetrabutylammonium, and Tetraethylammonium ions. Respectively... 

The derivative-forming process in pyrolytic alkylation involves two sequential reactions deprotonation of the acidic substrate in aqueous solution by the strongly basic tetra-alkylammonium ion and the thermal decomposition of the quaternary M-alkylammonium salt formed to give a tertiary amine and alkyl derivative. For some weak acids both processes may occur virtually simultaneously in the injector oven of the gas chromatograph. 

H30 + is also called the hydroxonium ion because it expresses (analogously with the ammonium ion) the donation of a proton to a lone pair of electrons of the oxygen it explains also the term alkoxonium ion for ROH (reaction 4.4) like the alkylammonium ion for RNH3+ (reaction 4.8) CH3COOH2f or AcOH may be called the acetoxonium ion... 

Vansant EF, Uytterhoeven JB (1972) Thermodynamics of the exchange on n-alkylammonium ions on Na-montmorillonite. Clays Clay Mineral 20 47-54... 

Weiss A (1963) Mica-type layer silicates with alkylammonium ions. Clays Clay Miner 10 191-224... 

The hemispherands, spherands, calixarenes, and related derivatives. A number of hosts for which the pre-organization criterion is half met (the hemispherands) (Cram et al., 1982) or fully met (the spherands) (Cram, Kaneda, Helgeson Lein, 1979) have been synthesized. An example of each of these is given by (251) and (252), respectively. In (251), the three methoxyl groups are conformationally constrained whereas the remaining ether donors are not fixed but can either point in or out of the ring. This system binds well to alkali metal ions such as sodium and potassium as well as to alkylammonium ions. The crystal structure of the 1 1 adduct with the f-butyl ammonium cation indicates that two linear +N-H - 0... 

The natural product westiellamide (158) and other unnatural cyclopeptide alkaloids were synthesised by cyclooligomerisation reactions <00T9143>. The benzene-based tripodal tris(oxazolines) 159 were developed as new selective receptors toward alkylammonium ions <00CEJ3399>. 

Rao and Singh32 calculated relative solvation free energies for alkyl- and tetra-alkylammonium ions using same conditions as described before for neutral molecules (except, atomic partial charges were not scaled for ions). The values obtained with coordinate coupling were in better agreement with... 

Scheme 3. Some of the compounds utilized for the discovery of a slippage synthesis involving the binding of di-alkylammonium ions by DB24C8.

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