Solubility maps

The phase diagrams were prepared at room temperature by the usual method, where a weighed aliquot of the surfactant/ cosurfactant mixture (E) was diluted with known amounts of water (W) and then titrated with oil (0) to turbid and clear endpoints. Alternatively, the dilution of E could be made with oil and titration with the water. Generally, fifteen to thirty titrations were sufficient to roughly outline the phase maps. Solubility limits were also determined by titration of the solvent with the solute (or solute solution) to a cloudy endpoint. 

Figure 10.1-2. A four-fold toroidal KNM map for 1 293 compounds obtained by using ihe 15 input descriptors high" means compounds v ilh high solubiiity where log S is in the range -2.82 to 1.58 "middle" means compounds with medium solubility where log 5 is in the range -7.21 to -2.83 low means compounds with low solubility where log S is in the range -11.62 to -7.22.

Experimental results describing limited mutual solubility are usually presented as phase diagrams in which the compositions of the phases in equilibrium with each other at a given temperature are mapped for various temperatures. As noted above, the chemical potentials are the same in the equilibrium phases, so Eqs. (8.53) and (8.54) offer a method for calculating such... 

Scotts technology (17) uses fluid-bed (Wurster column) technology to apply polymeric coatings to a number of fertilizer substrates including urea, potassium nitrate, potassium sulfate, and monoammonium phosphate (MAP). The coating material is appHed as a water-borne latex onto the fluidized substrate. As the substrate is fluidized with warm air (40—50°C), water is driven off and the latex coalesces into a continuous film around the fertilizer particle. The particular latex compositions used have selected glass-transition and blocking temperatures, which enable quick removal of the water before the soluble fertilizer core dissolves. This obviates the need to use precoats prior to the latex appHcation. 

Compare and contrast the electrostatic potential map of a typical detergent with that of a typical soap (stearate). Which part of each molecule will be most water soluble (hydrophilic) Draw a Lewis structure that describes each molecule s water-soluble group (make sure you indicate all necessary formal charges and lone pairs). Which part(s) of each molecule will be most grease soluble (lipophilic) What kinds of atoms and bonds are found in these groups ... 

What properties oibenzyltriethylammonium ion make it soluble in diverse solvents Examine its electrostatic potential map and atomic charges. Which groups facilitate water solubility Explain. Which groups facilitate chloroform solubility Explain. 

Compare electrostatic potential maps for tetrabenzyl-ammonium ion and tetraethylammonium ion with that of benzyltrimethylammonium ion. Are they likely to be as effective or more effective as phase-transfer catalysts as benzyltrimethylammonium ion Explain. (Hint Predict solubility properties for the three ions.)... 

Compare the spin density surface for vitamin E radical to those of phenoxy and BHT radicals (see also Chapter 16, Problem 2). Are there significant differences among the three If so, elaborate. What is the function of the long alkyl chain in vitamin E Examine an electrostatic potential map for vitamin E radical. Do you expect it to be soluble in aqueous (polar) or non-aqueous (non-polar) environments, or both ... 

Now, we should ask ourselves about the properties of water in this continuum of behavior mapped with temperature and pressure coordinates. First, let us look at temperature influence. The viscosity of the liquid water and its dielectric constant both drop when the temperature is raised (19). The balance between hydrogen bonding and other interactions changes. The diffusion rates increase with temperature. These dependencies on temperature provide uS with an opportunity to tune the solvation properties of the liquid and change the relative solubilities of dissolved solutes without invoking a chemical composition change on the water. 

Avdeef, A., Bendels, S., Tsinman, O., Tsinman, K., Kansy, M. Solubility-excipient classification gradient maps. Pharm. Res. 2007, 24, 530-545. 

The potential binding sites for various SH2 domain proteins on cytoplasmic receptor domains as well as on soluble proteins have been precisely mapped for several pTyr-containing target proteins. Apart from the impressive diversity of SH2 domain function, the fundamental property of all SH2 domains refers to the specific recognition of pTyr epitopes. 

Solubility Diagrams effects of atomic properties on mutual solubility. The effect on mutual solubility of the atomic properties of the components (and therefore of their relative positions on the map shown in Fig. 2.8) may be considered on the basis also of different diagrams. 

For a review of the application of the Darken and Gurry method to predict solid solubility see Gschneidner Jr. (1980). An improvement of the method by means of simultaneous use of rules based on the electronic and crystal structures of the metals involved is also presented. Notice that, in a way, the Darken and Gurry diagram corresponds to a row, or to a column, of the map reported in Fig. 2.8. 

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