Chloride ion transfer

Despite this, they are good solvents for chloride-ion transfer reactions, and solvo-acid-solvo-base reactions (p. 827) can be followed conductimetri-cally, voltametrically or by use of coloured indicators. As expected from their constitution, the trihalides of As and Sb are only feeble electron-pair donors (p. 198) but they have marked acceptor properties, particularly towards halide ions (p. 564) and amines. 

SeOCl2 (Table 16.7) is a useful solvent it has a high dielectric constant (46.2 at 20°), a high dipole moment (2.62 D in benzene) and an appreciable electrical conductivity (2 x 10 ohm cm at 25°). This last has been ascribed to self-ionic dissociation resulting from chloride-ion transfer 2SeOCl2 SeOCl " -)-SeOCl3-. 

They argue that the similar coordinating ability of these phusphoryl (—P=0) solvents (and to a lesser extent their dielectric constants) is more important than their chemical differences (supposed autoionization and chloride ion transfer in phosphorus oxychloride). 

Reaction 9 shows that the major portion of the reacting ethylene ions interact with ethyl chloride by discrete transfer steps including H" transfer, H2" transfer, and possibly Cl" transfer. Also, as discussed later, the total cross section for reaction of ethylene ions in this system is quite large (> 100 sq. A.). This may be compared with the corresponding reaction of ethylene ions with ethane, for which extremely small cross-sections have been found (44). In the latter case, however, the H" transfer reaction is endothermic, and the H2" transfer process would not have been detected in the previous experiments. These facts may explain the low reactivity reported. With ethyl chloride, H" transfer to ethylene ions is also indicated to be endothermic by the usual calculations. This suggests that the reactant ethylene ions in this system may well be vibra-tionally excited. It would also account for the chloride ion transfer to this ion, mentioned above. The ratio of rate constants observed for C2H4+ reaction with ethyl chloride is kU2-/ku- = 1.4. In addition to the reactions just discussed, part of the ethylene ion reactant forms a complex intermediate with CoH5C1, and elimination of HC1 and DC1 from this intermediate occurs with about equal probability. 

Solvates of acetonitrile can be obtained through the method of chloride-ion transfer. This can be performed through the nitromethane precursors, but also directly in acetonitrile itself. Acetonitrile is inert, unlike acetone, toward strong Lewis acids and is also a fairly good solvent for this type of coordination compound. In addition, Lewis acids weaker than SbCl, can be used as chloride-ion acceptors to form the chloroanions in acetonitrile, because acetonitrile is a stronger solvate-forming ligand than nitromethane. 

Further inspection of the agreement of the SL model with observed Gibbs transfer energies suggests the involvement of underlying donor-acceptor factors. Previously, it was found for chloride ion transfer into various... 

As was previously mentioned, Artephius described the process of the Philosophers Stone using Antimony in about 1120 or 1150 CE. It rapidly became the divine Wet Method of producing the Philosophers Stone used by all the great alchemists. Antimony Trichloride is today widely used as an excellent non-aqueous solvent, especially for chloride-ion transfer-reactions. It avoids troublesome nitrates altogether by using chloride ion transfer. 

For covalent fluorides as solvents fluoride ion-transfer is postulated and for covalent chlorides chloride ion-transfer ... 

Self-ionization equilibria have been assumed to exist in the pure liquids. Davies and BaughanI have shown that the self-ionization in molten antimony (III) chloride is hkely to be principally due to the presence of small amounts of impurities, but the results are still at least partially in accord with the following equations, which have been regarded as due to chloride ion transfer reactions between solvent molecules ... 

The extent of chloride ion transfer reactions has been extensively studied by spectrophotometric techniques. One of the approaches has been based on the pronounced differences in spectra between solvent-coordinated and fully chloride-coordinated ferric chloride in phosphorus oxychlorideio and phenylphosphonic... 

Potentiometric and spectrophotometric methods have been used to obtain information about the extent of chloride ion transfer with the formation of chloronium ions and thus about the chloride ion donor strength of metal chlorides in different oxyhalides solvents. The chloride ion donor properties are increased by a solvent of high donor number and decreased by a weak donor solvent, if the chloronium ions are solvated. Thus the chloride ion donor strength of a particular chloride is higher in phenylphosphonic dichloride than in phosphorus oxychloride and is usually non-apparent in benzoyl chloride ... 

In agreement with the results of preparative work it was concluded that the solvent cations replace phenolic hydrogens in the indicator molecules on dissolution in phosphorus oxychloride with formation of hydrogen chlorideii Colour changes are regarded as due to chloride ion transfer reactions ... 

Colour indicators, such as crystal violet may be used to follow chloride ion transfer reactions, the reactions being analogous to those described in phosphorus oxychloride (p 124 and 125). 

Due to the high donor properties of the solvent molecules halide ion-transfer reactions are limited in solutions of dimethyl sulphoxide. Although in the system C0CI2—TiCU chloride ion transfer gives in acetonitrile Co++ and [Tide]" and in trimethylphosphate [CoCla]" and [TiCla], no halide transfer is observed in dimethyl sulphoxide Complex iodides and complex bromides of class (a)... 

There are a number of solvents in which chloride-ion transfer is believed to be important, e.g. POCI3, SeOCl2, SOCI2, NOCl and COC12- A self-ionization involving such a chloride ion transfer... 

Here AI2CI7" is the characteristic acidic ion and Cl" the characteristic basic ion. This is again the chloride-ion transfer reaction. Addition of AICI3 increases the acidity of the solution while the addition of CP increases the basicity. In molten sulphates an analogous equilibrium is set up ... 

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