Solubilization in non-aqueous solvents

Most of the work using non-aqueous solvents has been concerned with the solubilization of water and small polar molecules and has examined the effect of surfactant structure and the nature of the solvent phase on the solubilizing capacity. 

One of the structures proposed for an ionic reverse micelle containing solubilized water is shown in Fig. 5.28 (see Chapter 3 for alternative models). Since micelles in non-aqueous solvents have their polar groups directed inwards and their hydrophobic groups in contact with the solvent, water or small polar 

Palit and Venkateswarlu investigated the solubilization of water by a series of organic acid salts of n-dodecylamine in xylene and reported maximum solubilization with butyrate salts [204]. A similar trend was observed with salts of n-octadecylamine in xylene, maximum solubilization being observed with the propionate salt. The amount of water solubilized by w-dodecylamine and n-octadecylamine salts of several carboxylic acids in benzene or cyclohexane was greatest for the shortest chain carboxylate [205]. The effect of electrolyte in decreasing the minimum temperature of solubilization and increasing the maximum amount of water solubilized in dodecylammonium carboxylates in 

The solubilization of water in mixtures of ionic surfactants was studied by Palit and co-workers [206, 207] using dodecylamine derivatives and lauryl and hexadecylammonium bromide derivatives dissolved in various organic solvents. In general, solubilization is enhanced over the value for a single surfactant when mixtures of the two surfactants are present, provided that one surfactant is hydrophilic and the other lipophilic, such as a mixture of dodecylamine chloride and dodecylamine laurate. 

The solvent can have a pronounced influence on the solubilizing capacity of an ionic surfactant due, in many cases, to differences in aggregate size in the various solvents. Thus the solubilization capacity of Aerosol OT was found to decrease with increase of chain length of hydrocarbon solvents over the range heptane to octadecane [196, 208]. 

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