Singly-charged anions

It was found that utilization of QAS with increased steric accessibility of exchange center, containing nitrogen atom with three methyl substituents and one super lipophilic substituent, - tris(2,3,4-dodecyloxy)benzyl, - leads to dramatic, up to 7 orders, increase of ISE s selectivity towards sulfate in the presence of single-charged anions. Incorporation of hexyl 4-trifluoro-acetylbenzoate into membrane leads to additional substantial increase - up to 4 orders - in sulfate selectivity. 

Table 9. Hydration Free Energies of Singly Charged Anions of Dicarboxylic Acids3...

Table 2. Representative values of the dehydration rate constant and the complex formation rate constant for a singly and a doubly charged anionic ligand for several metals in aqueous solutions. An ionic strength of 0.01 mol dm 3 was assumed. T] is the half dissociation time (equivalent to O J/ka) for a singly charged anionic ligand with a stability constant of 106 dm3 mol. Based on [5,164,172]...

The initiation of the cationic polymerisation of alkenes is examined in detail by means of simple thermodynamic concepts. From a consideration of the kinetic requirements it is shown that the ideal initiator will yield a stable, singly charged anion and a cation with a high reactivity towards the monomer by simple, well defined reactions. It must also be adequately soluble in the solvent of choice and for the experimental method to be used. The calculations are applied to carbocation salts as initiators and a method of predicting their relative solubilities is described. From established and predicted data for a variety of carbocation salts the position of their ion molecule equilibria and their reactivity towards alkenes are examined by means of Born-Haber cycles. This treatment established the relative stabilities of a number of anions and the reason for dityl, but not trityl salts initiating the polymerisation of isobutene. 

In summary, a good initiator will yield a stable, singly charged anion and a cation with a high reactivity (large kf) towards the alkenes concerned, via simple, well defined reactions. The remainder of this paper is concerned with finding, by appropriate calculations, some carbocation salts which best meet the specified requirements. 

For correlation of the coefficients we have found two parameters for which values are known for all or most of the single-charged anions in the data base and also for bicarbonate and hydrosulfide. These are the entropy of the ion and the thermochemical radius of the ion as calculated by Yatsimirskii(37,38). 

Although its precise structure has not yet been settled, the hydrated electron may be visualized as an excess electron surrounded by a small number of oriented water molecules and behaving in some ways like a singly charged anion of about the same size as the iodide ion. Its intense absorption band in the visible region of the spectrum makes it a simple matter to measure its reaction rate constants using pulse radiolysis combined with kinetic spectrophotometry. Rate constants for several hundred different reactions have been obtained in this way, making kinetically one of the most studied chemical entities. 

Citric acid is a polyprotic acid with pK, pK2, and pKj equal to 3.15, 4.77, and 6.39, respectively. Calculate the concentrations of H+, the singly charged anion, the doubly charged anion, and the triply charged anion in 0.0100 M citric acid. 

FIGURE 3.6 A neutral (TRITC-Arg A and D), a singly charged anion (TRITC-Gly B and E), or a doubly charged anion (TRITC-Asp C and F) is continuously electrophoresed. Preferential transport of anions into the field-free channel (ff) at a tee intersection. The electro-osmotic velocity in the side or ground channel (g) has been reduced relative to that in the separation channel (sep) by selectively coating the ground channel with a viscous polymer [387]. Reprinted with permission from the American Chemical Society. 

Figure 130 Absorption (A), photoluminescence (PL) and electroluminescence (EL) spectra of a Langmuir-Bloddgett (LB) film (a) containing a donor-conjugated Ti-electron system acceptor (D-T-A) molecular cation coupled to a monovalent anion with a trivalent rare-earth (Nd3+) cation surrounded by four organic singly charged anionic ligands (b). The two EL spectra have been taken from a device being run for the first time (ELI), and the emission from a device that has been cycled several times (EL2). Reprinted from Ref. 512. Copyright 1996 with permission from Elsevier.

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