Solubility ion pair

The slightly soluble ion pair was used as electrode-active substance in a plastered membrane of an ion-selective electrode (ISE) for these alkaloids. 

All of the methods described and referenced here are capable of producing high-quality, accurate results, but only if the raw data are correctly interpreted and analyzed to detect (and correct) for issues arising from issues such as low solubility, ion pair partition or multiple ionizable groups with overlapping pKas. It is not... 

The reaction of diorganozincs bearing bulky trimethylsilyl-substituted methyl groups and methyl- or phenyllithium in the presence of the 1,3,5-trimethyl-1,3,5-triazacyclohexane (TAGH), Scheme 53, afforded the corresponding lithium zincates as poorly soluble ion pairs.124... 

The mechanism by which cations are transported across a membrane is represented in Figure 18a. A cation-carrier complex is initially formed at the interface. This lipophilic species then diffuses across the membrane as an ion pair and dissociates at the other interface to water soluble ion pair and membrane-soluble carrier. The final step is back diffusion of the free carrier to the initial interface. The factors which influence transport rates and selectivity have been the subject of much research (79PAC979, B-81MI52102). 

A RhCl3-Dowex 1 anion exchanger ion pair is an efficient and recyclable catalyst to induce hydration of acetylenes.560 Whereas the soluble ion pair mediates oligomerization, this solid catalyst transforms phenylacetylenes to the corresponding methyl ketones in high yields. 

The solubility product does not tell the entire story of solubility. In addition to compli-A salt is any ionic solid, such as Hg2Cl2 or cations described in Box 6-1, most salts form soluble ion pairs to some extent. That is,... 

It is believed that the formation of fat soluble ion pairs is responsible for the increased permeation in the above cases. However, additive interactions with stratum corneum or increases in the diffusive driving force in the film may also contribute to the increase. 

Tetraalkylammonium salts are the most common electrolytes for the non-aqueous solvent systems and high molecular weight ammoniums have been used for the ion-pair extractant. The thermodynamic properties of the salts such as partition equilibria, solubility, ion-pair formation etc. have been studied in a variety of solvents. The detailed equilibria or structure of ion pair, however, are not fully elucidated. 

With Rhodamine B (formula 4.29) the antimony(V) chloride complex, SbCle , forms a sparingly water-soluble ion pair, which is extractable into benzene or DIPE. The violet-pink solutions of the complex in these solvents are the basis of a sensitive spectrophotometric method for antimony [28,35]. Rhodamine B dissolves in acid, giving a pink solution, but is insoluble in benzene and DIPE. 

This mechanism has been used to separate isomers, but contrary to the above argument, the reverse order of Rv values has also appeared in the literature [17— 23], The differences in Rv values for cis and trans isomers may originate in the differences in dipole moments, solubilities, ion-pair formation between the complex cation and the anion present in the species, stability, steric hindrance, adsorp-tivity and symmetry of the complexes. All these physical differences allow the use of the solubility of complexes to separate their isomers. 

Plant material, especially seeds and leaves, often contain large amounts of fatty compounds. These have to be removed before alkaloid extraction and is most frequently done with petroleum ether. Petroleum ether has the advantage that most alkaloids are not removed with this solvent. Another way to remove fatty compounds and other impurities is acidification of the aqueous extract followed by extraction with an organic solvent. The alkaloids remain in the aqueous phase while the fatty compounds are removed by the organic solvent. The choice of acid for acidification is important as several anions will result in the formation of organic solvent-soluble ion pairs with the alkaloids (e.g., chloride and acetate). After extraction with organic solvent, the aqueous phase is made basic, and the alkaloids are extracted with an organic solvent. 

In 2003, the initial stages of the heterogeneous photoreduction of quinone species by self-assembled porphyrin ion pairs at the H20-1,2-DCE interface were studied by ultrafast time-resolved spectroscopy and dynamic photo-electrochemical measurements. Photoexcitation of the water-soluble ion pair formed by ZnTPPS and ZnTMPyP + leads to a charge-separated state of the form ZnTPPS -ZnTMPyP + within 40 ps that can inject electrons to acceptors in the organic phase in the microsecond time scale, resulting in photocurrent responses [228]. 

A useful property of the tetrahydroxyborate ion in solution is its ability to form soluble ion-pair complexes with cations, notably the hardness ions, calcium and magnesium (M +) [18] ... 

It is possible, but not yet proven, that the borate ion acts in a way similar to the sulfate ion. Like the sulfate anion, it does form soluble ion-pair complexes with calcium and magnesium ions and this may promote coadsorption on the chalk surface. However, in the absence of reliable data on borate ion adsorption and zeta potential data for chalk, it is difficult to confirm the mechanism behind the observed imbibition performance of borate. 

Chiral anion phase-transfer catalysis has been extended to the asymmetric synthesis of allylic fluorides (Scheme 7.10) [20]. The key with this chemistry was judicious selection of the electrophilic fluorine source. Selectfluor displays poor solubility in nonpolar solvents such as cyclohexane however, combining this F source with a chiral phosphate salt generated afforded a soluble ion pair that promoted the chemistry. A wide range of... 

Tetrakis chelate anions formed when either a silver or potassium P-diketonate is mixed with a lanthanide tris P-diketonate are effective shift reagents for organic-soluble salts. Adding an organo-halide or fluoroborate salt leads to precipitation of silver halide or potassium fluoroborate, resulting in an organic-soluble ion pair. These reagents have been used to enantiomerically resolve the spectra of chiral isothiouronium and sulfonium ions. 

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