Hydrogen-bonded solvents, electrical conductivity

Besides these special physical properties, hydrogen-bonded liquid water also has unique solvent and solution properties. One feature is high proton (H ) mobility due to the ability of individual hydrogen nuclei to jump from one water molecule to the next. Recalling that at temperatures of about 300 K, the molar concentration in pure water of H3O ions is ca. 10 M, the "extra" proton can come from either of two water molecules. This freedom of to transfer from one to an adjacent "parent" molecule allows relatively high electrical conductivity. A proton added at one point in an aqueous solution causes a domino effect, because the initiating proton has only a short distance to travel to cause one to pop out somewhere else. 

When the relative permittivity of the organic solvent or solvent mixture is e < 10, then ionic dissociation can generally be entirely neglected, and potential electrolytes behave as if they were nonelectrolytes. This is most clearly demonstrated experimentally by the negligible electrical conductivity of the solution, which is about as small as that of the pure organic solvent. The interactions between solute and solvent in such solutions have been discussed in section 2.3, and the concern here is with solute-solute interactions only. These take place mainly by dipole-dipole interactions, hydrogen bonding, or adduct formation. 

A solvent, in addition to permitting the ionic charges to separate and the electrolyte solution to conduct an electrical current, also solvates the discrete ions, by ion-dipole or ion-induced dipole interactions and by more direct interactions, such as hydrogen bonding to anions or electron-pair donation to cations. Lewis acidity and basicity of the solvents affect the latter. The redox properties of the ions at an electrode depend on their being solvated, and the solvation effects electrode potentials or polarographic half-wave potentials. 

This calls for the 1,4-addition to take place at least at some positions, which prevents the fluorinated tube from being an electric conductor. Fluorinated nanotubes differ from the unmodified species not only in electric conductivity. There are rather more characteristics being changed. Fluorinated tubes dissolve, for instance, in some organic solvents Uke DMF, THF, and different alcohols. Most of aU, the solubility in 2-propanol and 2-butanol is increased. Hydrogen bonds between the protons of the hydroxy groups and the fluorine atoms of the nanotubes are assumed to cause an effective solvation. 

Hydrogen bond formation as a result of the interaetion of polymer with solvent was found to contribute to changes in the electric properties of polyaniline.Hydrogen bonding causes changes in conformal structure of polymer chains. This increases the electrical conductivity of polyaniline. Water is especially effective in causing such changes but other hy-... 

Phosphoryl chloride is a non-protonic solvent, but its properties show a remarkable resemblance to those of water (Table 4.25). The low electrical conductivity of both solvents indicates only slight dissociation (4.319), (4.320). The extensive system of hydrogen bonds, characteristic of water, is of course absent in phosphoryl chloride. 

Protic or aprotic Ionic Liquids [21]. Protic ionic liquids (PILs), as all other protic solvents can give away protons and, more important, can form hydrogen bonds. As a result, they are not necessarily fully dissociated and can be distUlated more easily (though still xmder extreme conditions) than aprotic Ionic Liquids (AlLs). Further, they are considered to be poor ILs in the sense that their electrical conductivity is lower than what is predicted by the Walden plot. FAN is a representative example of a PIL. 

---