Supporting electrolytes table

The use of Ce(IV) to probe the kinetics of outer-sphere electron transfer reactions has centered on compounds of the title metal ions whose primary coordination spheres (in the reduced state at least) are substitution inert on the time scale of electron transfer reactions. For example, Cyfert et al. (1980) investigated the effects of the variation of ionic strength on the rate of Fe(phen) oxidation by Ce(IV) in 0.125 M H2SO4 with different supporting electrolytes (table 9). Variation in the concentrations of NaCl or NaClO in the range of O.l-l.O M changed the rate constants from 1.08 to 0.81 X 10 s and 1.03 to 0.56 x 10 M s, respectively (25°C). The varia-... 

TABLE 2 Concentrations of Redox Products After the Electrolysis for 4 h by Applying a Definite E appi at the Stationary Interface Between W Containing 10 M H2O2 and DCE containing 10 M Tetrachlorohydroquinone, CQH2, Under the Deaerated Condition. As Supporting Electrolytes, 0.5 M Li2SO and 0.05 M TPenA+TEPB Were Added in W and DCE, Respectively. The pH of W Was Adjusted with the Aid of 0.1 M Phosphate Buffer to be 7.0... 

Supporting electrolytes are listed in approximate order of preference. These supporting electrolytes were selected from commonly available literature sources and are not meant to be all-inclusive. Abbreviated electrolytes are explained following the table. 

Supporting Electrolytes The list below includes only those supporting electrolytes which were abbreviated for the table. 

Densification is also influenced by the presence of supporting electrolyte. As shown in the last line of Table II, the relative densification in acidified cupric sulfate is less than that in binary cupric sulfate solution. In the case of the supported redox reaction, that is, in the presence of KOH or NaOH, the migration effect makes the density difference larger than that expected from overall reaction stoichiometry. 

Some of the two-electron charge transfer reactions which have recently been studied are Cu(II)/Cu(s), Ni(II)/Ni(s), Cd(II)/Cd(s), and Zn(II)/Zn(s). Their kinetic parameters in different supporting electrolytes are given in Tables 1 and 2. 

Recently, the kinetic parameters for each step of this reaction in different supporting electrolytes have been obtained39,42 by applying the faradaic rectification theory as extended to multiple-electron charge transfer reactions. The kinetic parameters are listed in Table 1. 

Considering the activity of the finally reduced species in the second step of reduction, i.e., M+ M(s), as 1.0, the value of k is invariably found to be much higher than that of k° in all supporting electrolytes. For the sake of comparison, such values are also included in Table 1. 

The nature of AE /V versus P1/2 plots is similar for all supporting electrolytes to those shown in Fig. 5 for a KN03 medium. The kinetic parameters are given in Table 1. 

Similar FR polarograms and AEoo/ V2A versus o) 1/2 plots are obtained for T1(I) in other supporting electrolytes, and the respective values of a and k°a have been obtained. The kinetic parameters are given in Table 6. As the FR polarograms in all the supporting electrolytes are obtained on the negative side of the abscissa, the transfer coefficient is expected to be less than 0.5, and it lies between... 

Some typical results are shown in Table 2. The table shows that oxidation of conjugated dienes such as isoprene, piperylene (1,3-pentadiene), cyclopentadiene and 1,3-cyclohexadiene with a carbon anode in methanol or in acetic acid containing tetraethylammonium p-toluenesulfonate (EtjNOTs) as the supporting electrolyte yields mainly 1,4-addition products2. 1,3-Cyclooctadiene yields a considerable amount of the allylically substituted product. 

Cyclooctatetraene and some of its derivatives are electrochemically reducible in dry degassed DMF containing BU4NCIO4 as the supporting electrolyte. The first reduction peak potentials which are required to form the corresponding anion radical are shown in Table 824, though a further reaction of the intermediates is not known. 

Chemical reactivity of unfunctionalized organosilicon compounds, the tetraalkylsilanes, are generally very low. There has been virtually no method for the selective transformation of unfunctionalized tetraalkylsilanes into other compounds under mild conditions. The electrochemical reactivity of tetraalkylsilanes is also very low. Kochi et al. have reported the oxidation potentials of tetraalkyl group-14-metal compounds determined by cyclic voltammetry [2]. The oxidation potential (Ep) increases in the order of Pb < Sn < Ge < Si as shown in Table 1. The order of the oxidation potential is the same as that of the ionization potentials and the steric effect of the alkyl group is very small. Therefore, the electron transfer is suggested as proceeding by an outer-sphere process. However, it seems to be difficult to oxidize tetraalkylsilanes electro-chemically in a practical sense because the oxidation potentials are outside the electrochemical windows of the usual supporting electrolyte/solvent systems (>2.5 V). 

Table 15 Electrochemical data for [67] in acetonitrile containing 0.2 mol dm 3 BunNBF4 as supporting electrolyte (4 equiv cation salt added).

Table 11 Anodic oxidation of ST-Bu4NNu in acetonitrile with tetraethylammonium perchlorate as supporting electrolyte."...

Coming back to Table 2, it also reports the most suitable supporting electrolytes for each solvent (generally they are quaternary alkylammo-nium salts). 

Table 1 Typical tabulation of cyclic voltammetric data. [Fe(f-C5H )2)] solution (1.0 X 10 3 mol dm 3) in CH2CI2. Supporting electrolyte [NBu4][PF6] (0.2 mol dm 3). Platinum disc electrode radius = 1 mm. Potential values are referred to SCE...

Table 6 Formal electrode potential (V vs. SCE, at 25° C) for the one-electron oxidation of a few substituted ferrocenes. Dichloromethane solution [NBu4][CIO4] supporting electrolyte...

The observed disaepancies in experimental results is most likely caused by the ions of the supporting electrolyte. For example, fluoride ions do not adsorb on the mercury electrode but adsorb on the silver electrode. The adsorption on the latter metal strongly depends on the face orientation.The sequence of AG° values forn-hexanol adsorption from Na2S04 and KCIO4 solutions is AC° [Ag(lll)] > AG° [Ag(lOO)] (see Table 3). However, the sequence of AG°s of n-pentanol adsorption from KF solution is just the opposite [Ag(l 10)] > AG° [Ag(l ll)]. The... 

The study of thiourea adsorption on an Hg electrode from ethanolic solutions shows that different supporting electrolytes can make a comparison of the adsorption parameters more difficult. The data obtained for various electrolytes (KF, KPFe, LiCl, NH4NO3, and KCNS) suggest that coadsorption, size, and polarizability of ions strongly influence the interfacial behavior of TU, at high concentration of the ions in particular. The effect of the electrolyte on AG° and parameter A in the Frumkin isotherm is illustrated in Table 6. 

Adsorption studies of acetone on mercury show that the AG° values depend not only on the type of supporting electrolyte but also on its concentration. " " The relevant data are given in Table 7. An increase in the KPFg concentration in NM -i- Ac from O.OIM to saturation results in a AG° drop by a factor of 2, with a simultaneous slight change in ffmax from -7.5 to -8 /rC/cm (Fig. 14). In the case of an MeOH + Ac system, an increase in the LiCl concentration also leads to a decrease in the AG° value but to a lesser extent than in the former case. The change of the o-max is greater, however, from -4 to -8 /rC/cm. ... 

Styrene and indene derivatives (Scheme 2, Y = Ph) are dimerized to l,4-dimethoxy-l,4-diphenylbutanes or 1,4-diphenylbutadienes (Table 7, numbers 1 and 2) [52]. The product distribution is in some cases strongly dependent on the anode potential and the supporting electrolyte. Dimerization is promoted by a-substituents that stabilize the intermediate radical cation, for example, phenyl, vinyl, alkoxy, dialkylamino groups. IJ-Alkyl substituents strongly decrease the yield of dimers and favor formation of dimethoxy-lated monomers. 

Table 5. Influence of supporting electrolyte on stereoselectivity in the reductive cyclization of 52 and 53...

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