Interionic reactions

Several papers compare the properties of sulfobetaine (meth)acrylic polymers. NMR spectra and solution properties of 23a and 23b [59,60] are correlated with data from the corresponding polycarbobetaines [26]. The photophysical and solution properties of pyrene-labeled 23c were studied in terms of fluorescence emission. Addition of surfactants induces the formation of mixed micelles in aqueous solution [61]. Excluded volume effects of the unlabeled polymer were measured by light scattering [62], its adsorption on silica was studied by adsorbance measurement and ellipsometry [62,63], and the electrostimulated shift of the precipitation temperature was followed at various electric held intensities [64]. Polysulfobetaines may accelerate interionic reactions, e.g., oxidation of ferrocyanide by persulfate [65]. The thermal and dielectric properties of polysulfobetaines 23d were investigated. The flexible lateral chain of the polymers decreased Tg, for which a linear relationship with the number of C atoms was shown [66,67]. 

Recently, keen attention has been paid to the catalytic action of high molecular weight compounds [1]. It has been found that, under appropriate conditions, these compounds are much more efficient in accelerating chemical reactions than corresponding low molecular weight compounds. In our group, intensive studies have been carried out mainly on interionic reactions and polyelectrolyte influence thereon. In this article, we would like to review the recent progress of our work the present review is by no means comprehensive. The relevant contributions from other laboratories will be mentioned sufficiently to place our research in perspective. 

The electrostatic interactions are also responsible for unusual, kinetic features of interionic reactions. The change of the rate constants of these reactions with ionic concentration was accounted for by Bronsted in terms of the Debye-Hiickel theory and an activated complex theory [3]. For a reaction between two ions, A- -B Z->Ch-D, (X the activated complex, C and Z) the products), the rate constant is... 

If substrates contain hydrophobic moiety, interionic reactions between oppositely charged ionic sp)ecies, which should be decelerated by polyelectrolytes according to the electrostatic model, can be even accelerated by hydrophobic polyelectrolytes. Examples are alkaline fading reactions of triphenylmethane dyes [34], which take place between dye cations and hydroxyl ions to form carbinols. In addition to three benzene rings, these dyes have alkyl groups ... 

The forward process of an equilibrium reaction between /9-nicotinamide adenine dinucleotide (Coenzyme I) and CN was accelerated by polycations 1c/t was 20 by an addition of CisBzPVP at a concentration of 7 x 10 eq. 1 [35]. This is quite a reasonable result because this is an interionic reaction between anions. At the same concentration, Tc/lc was 3. 

An exceptional case for interionic reactions was reported for oligomers of vinylimidazole, which were less efficient than imidazole in solvolysis of 4-acetoxy-3-nitrobenzenesulfonate [65]. 

Arrhenius believed that the decrease in conductivity observed with increased concentration resulted from decreased dissocation. In 1923, Debby and Huckel were able to establish that the decrease in conductivity was not due to reduced dissociation but from interionic reaction. 

If we go on to consider the reaction (66) in a solution so dilute that the interionic forces make a negligible contribution to the communal term in AF, we may refer to the cratic term, instead of the communal term we may describe the equilibrium by saying that the concentrations of the four species adopt values which give to the cratic term iu (60) a value equal and opposite to that of the unitary term ... 

In Fig. 11, the polyelectrolyte influences on the PNPP hydrolyses are shown. Though reaction (4) is not an interionic one, the present reaction was accelerated with the... 

Some examples of micellar rate enhancements of bimolecular reactions of electrophiles are shown in Table 5. Generally the surfactant was SDS with added electrophile, e.g. H30+ or a metal ion, but sulfonic acids were also used so that HaO+ was the counterion and there was no interionic competition. The maximum rate enhancements, knl, depend upon the specific conditions of the experiment, and, as predicted by the pseudophase ion-exchange model, generally decrease with increasing concentration of the electrophilic ion. In some cases the reactions were too fast for measurement... 

It seems that the reactivities of ion pairs and free ions cannot be readily compared. It may be imagined that a polarization of the CH2 S bond in the monomer occurs before the ring opening and is induced by the ion pair dipole of the living end. Such a modification should Increase with the magnitude of the ion pair dipole and then with the interionic distance This leads to an Increase of the interaction with the monomer, together with the reaction rate. It is understandable that the modification of the polarization of the CH2-S bond may be quite different when the interaction occurs with free ions. 

Jaksic, M.M. (2001) Hypo-hyper-d-electronic interactive nature of interionic synergism in catalysis and electrocatalysis for hydrogen reactions. Int.J. Hydr. Energy,... 

If one studies only the fluorescence quenching by irreversible bimolecular ionization (3.52), there is seldom any need to trace the fate of the charged products. On the contrary, those who are interested in photoinduced geminate recombination (3.188) rarely care about the kinetics of ionization, its quenching radius, and all the rest studied in Section III. All that they need to obtain the charge separation yield is the initial ion distribution mo(r), prepared by photoionization. However, the latter is scarcely so simple as in Eq. (3.201), which is usually favored. Even so, the initial separation ro is not a fitting parameter but the characteristic interion distance, which is dependent on the precursor reaction of photoionization. 

If ionization is neither fast nor slow, one has to solve numerically Eq. (3.290) together with the supplementary Eqs. (3.291) and (3.292) and use the result in Eq. (3.289). In Ref. 24 the numerical procedure based on the expanded DCR (diffusion-controlled reaction) program [182] was used to evaluate P t). From the simultaneously calculated initial distribution the root-mean-square interion distance was found ... 

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