Sodium counter ion

Figure C2.3.7. Snapshot of micelle of sodium octanoate obtained during molecular dynamics simulation. The darkest shading is for sodium counter-ions, the lightest shading is for oxygens and the medium shading is for carbon atoms. Reproduced by pennission from figure 2 of [36].

DR. THOMAS The kinetic parameters of micelles are very well known, having been determined by temperature-jump relaxation methods and various other techniques. There are several kinetic events which can be described. First of all, the fastest event is the exchange of the counter ion (e.g., the sodium counter ion, in sodium lauryl sulfate). These ions exchange... 

Experimental Information. The review by Ekwall — offers a whole series of phase diagrams which all show similar behavior. In order to dissolve an anionic surfactant with a sodium counter ion in an alcohol a minimum water/surfactant molar ratio of about six is needed to achieve solubility. The corresponding ratio for the potassium ion is three. 

Table 5 gives another list of results. In a kaolinite suspension prepared in distilled water, different salts were added together with the aluminium sulphate coagulant. The salt concentration in the suspension was always 10 M. The different cations had a chlorine counter-ion and the anions had a sodium counter-ion. In jar tests, the coagulant dose needed for a complete turbidity removal was determined, as was the corresponding E.M. of the floes. In the list of Table 5, only ions which can dissolve easily in the water are mentioned. At the given coagulant dose, the EJM. all had reached their constant values. 

In such a form this material is melt fabricable and after hydrolysis is converted to a ion exchange membrane with a perfluorosulfonate group, -S03Na. The sodium counter ion can be exchanged by other metal ion or hydrogen ion. 

To understand the mechanism of a separation, take for example an anionic column containing quaternary ammonium groups, in equilibrium with a mobile phase composed of a solution of hydrogenated carbonate anions (e.g. sodium counter ions). All of the cationic sites of the stationary phase find themselves paired with anions of the mobile phase (Figure 4.2). 

The water to surfactant molar ratio was the main variable studied for the anionic system. The water molecules were found to bind strongly to the surfactant polar groups and the sodium counter ions at to values below 4. This behaviour resulted in an inhibition of TEOS hydrolysis. As to was increased from 5 to 9.5, the particle size increased and the size distribution decreased. Furthermore, the size distribution of the particles prepared by the anionic system was broader than for the non-ionic system. 

The wave functions of the lowest two binding eneigy molecular orbitals of the doubly charged DP7, in the presence of two sodium counter-ions, are shown in Fig. 5. 

Here/ is the degree of binding of the sodium counter-ion, is the intrinsic dissociation constant for the acid and Kip is that of the ion pair (the reciprocal of its association constant). This treatment assumes random distribution of the three types of sites along the polyelectrolyte chain, but restrictions can be introduced, such as requiring an ionized site to be adjacent to the one where ion pairing takes place. Lif-son and Katchalsky (1948) took into account the mutual interaction of neighboring ionized sites, but the final result was the same as Eq. (2.78), i.e., as for the case where no such interaction was considered. 

We study zeta potential of several densities of polymer foils. Therefore zeta potential depends on counter-ion t)rpe and valence, but these effects do not play a role in the case of potassium and sodium counter-ion and observed differences are small for all pol)mer substrates [30], we finally used only potassium ions. The standard electrolyte was 0.001 mol/dm solution of KCl. The low electrolyte concentration ensures high sensitivity of the method [30,31,34]. To investigate the influence of electrolyte type and concentrations on -potential determination, two monovalent (s3mmetric) electrolytes KCl and KNOs of concentration 0.001 mol/dm and KCl also of 0.005 mol/dm we used [40]. 

Figure 5.14 Sodium dodecyl sulfate, an amphiphile comprising a hydrophilic sulfonate head group (hydrophilic head) and the 12-carbon alkyl chain (lipophilic tail) (sodium counter-ions not shown) self-assemblies to give a monolayer at the air - water interface.

Nucleophiles can also be neutral species such as amines, but such nucleophiles will be discussed in later chapters. In Section 6.2, an alcohol such as methanol (1) reacts with a base to give the conjugate base, an alkoxide (methoxide ion, 65). Compound 65 is formally known as sodium methoxide, and the oxygen is electron rich and may react as an electron donor. The reaction from Section 6.6 is written so that the sodium counter-ion is included because iodomethane has an electrophilic carbon atom, it will accept electrons from the oxygen atom of methoxide to form a new C-O bond and break the C-I bond. The blue arrows indicate the electron flow, which means the transfer of two electrons. The product is an ether—66, methoxymethane (dimethyl ether see Chapter 5, Section 5.6.4). 

Scheme 1.12 Transition state structures of some identity reactions of involving a nucleophile with the corresponding methyl derivative in the presence of sodium counter ion from computations (MP2/6-31H—l-G(d,p)) in gas phase.

Sodium hydroxide has been the most commonly used base in experimental nitroalkane proton transfer reaction studies.However, the computational studies of these reactions have generaUy been with hydroxide ion without the sodium counter ion. Recently a computational study of the proton transfer reactions of the three simple nitroalkanes in the presence of NaOH in water has been carried out and it was found that the presence of Na had an enormous effect on the energetics of the reactions. Double potential energy well diagrams, much like those found for the Sn2 reactions, were recorded for the proton transfer reactions of NM, NE and 2-NP with hydroxide ion in water. The computations included two explicit water molecules in the water cavity. The Gibbs free energies and enthalpies observed for the reactant complex (CPI), the TS and the product complex (CP2) both in the presence and absence of sodium ion and two explicit water molecules are summarized in Table 1.24. 

Clearly, the electrostatic stabilization of the enolate by the sodium counter-ion, in the low-dielectric solvent THF, decreases the reactivity of the anion. Were it possible to withdraw, even if very slightly, both partners of this ion pair from one another, i.e. lengthen d somewhat, and the anion reactivity will be increased. 

Three DNA metallization chemistries have been used to convert DNA into a conducting wire [5,8-10]. These chemistries fall into two reaction categories (1) ion-exchange of a metal (silver) ion for the positive sodium counter ion associated with the phosphate groups of the DNA backbone and (2) formation of a covalent bond between a metal ion (palladium or platinum) and amine groups of the DNA bases. In both cases, the attached ions are reduced to form a metal that can act as a catalytic site for the deposition of an alternate metal on the surface of the DNA [11],... 

The amount of chlorine in the human body is about 80 g. In hving organisms, chlorine mostly occurs in the form of anions, which are, together with sodium counter ions, located in the cytoplasm of cells and extracellular fluids (blood, gastric juice and urine). Their main role is, similarly to sodium ions, to maintain osmotic pressure. In the gastric juices, chlorides act as counter ions of hydrogen... 

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