Electrolyte, character

Ti(R2 fc)3Cl is a seven coordinated monomeric species, as is suggested from the spectral data and the non-electrolytic character and confirmed by an X-ray diffraction study (6). Apart from the chlorine compounds the bromine analogues are reported (9). 

The infrared spectra suggest bidentate dithiocarbamate coordination, the magnetic susceptibility is markedly field-dependent. Although the compound is monomeric in CHCI3, a molar conductance in nitromethane is found, which increases sharply on dilution, attributed to a weak electrolytic character. Accordingly, the authors formulate this compound as [Nb2(Et2r/tc)sBr2]Br. 

The solubilities of proteins vary considerably based on compositions and conditions of ionic strength, pH, and concentrations. Those with highest density of polar groups or electrolyte character are most soluble. Therefore, solubility in water is lowest at the isoelectric point and increases with increasing basicity and acidity. 

Proteins in the body liquids may be considered as a colloidal electrolyte solute in a water solvent. Contact with water is the natural state of a protein. In more or less dry form, a protein powder loses some of its electrolytic character it loses the charged double layer on the surface and behaves electrically very differently from protein with water. Such materials may well be mixed conductors—electronic in the dry state and ionic with water content. Keratin is a more or less dry protein found in the natural state of no longer living biological materials such as hair, nails, and the stratum corneum. The water content of such materials is dependent on the relative humidity of the ambient air. The question of ionic or electronic conductivity in proteins is important, and an electronic conduction mechanism must be considered in many cases. 

See also the chapter on colloids with electrolyte character. 

Although there is no proof available that this type actually exists in macromolecular substances, we will keep this possibility open. Under these circumstances a gel would be obtained without any material contact between the macromolecules, leading to the picture of Fig. Ic. It may be that in macromolecular sols with electrolytic character, where ionic swarms cause special attractive and repulsive forces, such gels are encountered. 

The macromolecules with electrolyte character can be divided into three categories, to wit ... 

System with electrolyte character The phenomena concerned with the swellii of hydrophilic macromolecular substances, such as proteins and cellulose, in aqueous solutions of electrolytes are more complicated and more difficult to understand theoretically, particularly if the macromolecules themselves represent electrolytes too, u e if they bear typically ionisable groups as e. g. the proteins. Since a great deal of the subject-matter has been treated elsewhere in this book (see Chapter VII), we shall confine ourselves here to some of its main features only. 

Thus far, the theoretical considerations dealing with this kind of systems have been of quite another nature than those tentatively advanced to explain the behaviour of the systems without electrolyte character. Obviously, a certain gap has remained between the two domains of thought. Nevertheless it would seem that in the near future this gap may be closed. 

Agar-agar must be also reckoned to the systems with electrolytic character as a result of the presence of sulphuric acid groups on the carbohydrate chains. 

The conditions enhancing or reducing swelling which have been discussed here, finally resolve themselves into the equivalents of an increase or a reduction of solubility , this being the same result as that arrived at in section a dealing with the systems without electrolyte character. 

We prefer the concept association colloids above other terms — for example colloidal electrolyte — because we want to leave open the possibility that non-electrolytes or undissociated electrolytes form particles with colloidal properties by association. Tlie association of small molecules or ions into micelles seems to us the more characteristic, not the electrolyte character which naturally plays a great part in soap solutions. Indeed particles which owe their character as colloids to their large molecules (for example proteins) also come under the concept of colloidal electrolyte. 

Within each of the two groups a second distinction can be made, namely whether one is dealing with systems with or without electrolytic character, taking this term in the broad sense. The irreversible systems have an electrolytic character whereby... 

Well-known examples are absorption columns, for example, the absorption of HCl in an exhaust air by water. Experience shows that quite large columns are required for this purpose, whereas the equilibrium calculation just requires one theoretical stage due to the electrolyte character of hydrogen chloride. Columns like that can only be successfully designed by application of a rate-based model (see also Section 14.5). 

A well-known example is the determination of the simultaneous solubility of carbon dioxide and ammonia in salt-containing waste water systems. As one sour gas (CO2) and one alkaline gas (NH3) are involved, they can react to nonvolatile ions, which considerably increase the solubility of these gases. Figure 7.10 gives a listing of the reactions occurring in the system CO2-NH3-H2O. The electrolyte character of the mixture is mainly determined by the formation of the carbamate ion NH2COO", which could not be predicted by conventional electrolyte dissociation reactions. 

For compounds of the first three classes, hexaammines, pentaammines, and tetraammines, the electrolytic character as predicted by the two theories is in complete agreement, and conductivity data do not permit a choice between the two. For triammines, however, the ionic character differs radically according to the two theories, and the conductivities of these compounds became an important and bitterly contested issue. For some nonelectrolytes, unfortunately, Werner and Miolati s conductivity values were not always zero because of aquation reactions such as ... 

A self-doped FT has been obtained from 3 -propanesulfonate terthiophene (62), which was selected because the trimer presents an oxidation potential lower than that of thiophene [165]. The electrolyte character of this compound is shown by the fact that its electropolymerization occurs in acetonitrile without the addition of a supporting electrolyte. 

A self-doped polythiophene has been prepared from 3 -propanesulfonate terthiophene (24) selected for the lower oxidation potential of the trimer compared with the monomer. This compound shows its electrolyte character by electropolymerizing in acetonitrile without addition of supporting electrolyte [113]. Self-doped polythiophenes with lower oxidation potentials and improved electrochemical behaviour have been prepared from 3-(co-carboxyalkyl)thiophenes with alkyl chains containing 4 to 14 carbon atoms (25) [173]. 

Polynucleotides are biopolymers that carry genetic information involved in the processes of replication and protein synthesis (4). An essentially infinite number, n, of proteins can be made by assembling the 20 amino acids in various miax>structural combinations and sequence lengths. The 20 amino acids contain four major types of side chains, i.e., hydrophobic, hydrophilic, basic and acidic. Most polypeptides and proteins are water-soluble or water-swellable. The solubility of proteins varies considerably based on composition and condition of ionic strength, pH, and concentration. Those wifii die highest density of polar groups or electrolyte character are the most soluble. Therefore, solubility in water is lowest at the isoelectric point and increases with increasing basicity or acidity. 

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