Solubility dielectric constant

Solvent Boiling Point, °C (760 torr) Freezing Point, Water Soluble Dielectric Constant (e) Flammable... 

Polyimides containing C—F bonds have been receiving strong attention (96—98). Fluorine-containing polyimides possess lower dielectric constant and dielectric loss because of reduced water absorption and lower electronic polarization of C—F bonds vs the corresponding C—H bonds. Fluorine-containing polyimides are often more soluble and readily processible without sacrificing thermal stabilities. The materials are appHed primarily iu... 

Table 1. Solubility of Aminophenols in Common Solvents Arranged in Order of Increasing Polarity (Dielectric Constant)...

Other. Insoluble alkaline-earth metal and heavy metal stannates are prepared by the metathetic reaction of a soluble salt of the metal with a soluble alkah—metal stannate. They are used as additives to ceramic dielectric bodies (32). The use of bismuth stannate [12777-45-6] Bi2(Sn02)3 5H20, with barium titanate produces a ceramic capacitor body of uniform dielectric constant over a substantial temperature range (33). Ceramic and dielectric properties of individual stannates are given in Reference 34. Other typical commercially available stannates are barium stannate [12009-18-6] BaSnO calcium stannate [12013 6-6] CaSnO magnesium stannate [12032-29-0], MgSnO and strontium stannate [12143-34-9], SrSnO. ... 

All stated pK values in this book are for data in dilute aqueous solutions unless otherwise stated, although the dielectric constants, ionic strengths of the solutions and the method of measurement, e.g. potentiometric, spectrophotometric etc, are not given. Estimated values are also for dilute aqueous solutions whether or not the material is soluble enough in water. Generally the more dilute the solution the closer is the pK to the real thermodynamic value. The pK in mixed aqueous solvents can vary considerably with the relative concentrations and with the nature of the solvents. For example the pK values for V-benzylpenicillin are 2.76 and 4.84 in H2O and H20/EtOH (20 80) respectively the pK values for (-)-ephedrine are 9.58 and 8.84 in H2O and H20/Me0CH2CH20H (20 80) respectively and for cyclopentylamine the pK values are 10.65 and 4.05 in H2O and H20/EtOH (50 50) respectively. pK values in acetic acid or aqueous acetic acid are generally lower than in H2O. 

Similar observations hold for solubility. Predominandy ionic halides tend to dissolve in polar, coordinating solvents of high dielectric constant, the precise solubility being dictated by the balance between lattice energies and solvation energies of the ions, on the one hand, and on entropy changes involved in dissolution of the crystal lattice, solvation of the ions and modification of the solvent structure, on the other [AG(cryst->-saturated soln) = 0 = A/7 -TA5]. For a given cation (e.g. K, Ca +) solubility in water typically follows the sequence... 

The effectiveness of nitromethane can be attributed to its high dielectric constant, at least in part, which tends to promote reactions which involve electron-rich intermediates. It may also result from the low solubility of the indole products in nitromethane since the indoles precipitate out of the reaction mixture in many cases. ... 

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. 

Solvent B.P. cc) Dielectric constant Water solubility (g/lOOg)... 

Fluorinated poly(arylene edier)s are of special interest because of their low surface energy, remarkably low water absorption, and low dielectric constants. The bulk—CF3 group also serves to increase the free volume of the polymer, thereby improving various properties of polymers, including gas permeabilities and electrical insulating properties. The 6F group in the polymer backbone enhances polymer solubility (commonly referred to as the fluorine effect ) without forfeiture of die thermal stability. It also increases die glass transition temperature with concomitant decrease of crystallinity. 

The use of SCFs as solvents influences the reacting system because it is possible to dramatically change the density of the fluid with small perturbations of temperature and pressure and, in such a way, greatly affect the density-dependent bulk properties such as the dielectric constant, solubility and diffu-sibility of these compressible fluids. 

Water in its supercritical state has fascinating properties as a reaction medium and behaves very differently from water under standard conditions [771]. The density of SC-H2O as well as its viscosity, dielectric constant and the solubility of various materials can be changed continuously between gas-like and liquid-like values by varying the pressure over a range of a few bars. At ordinary temperatures this is not possible. For instance, the dielectric constant of water at the critical temperature has a value similar to that of toluene. Under these conditions, apolar compounds such as alkanes may be completely miscible with sc-H2O which behaves almost like a non-aqueous fluid. 

Solvents Boiling Point rO Density (kg/m ) Solubility in Water (kg/100 kg) Dielectric Constant... 

The organic solvent should feature a low solubility in water and a high dielectric constant. Numerous studies have been reported for liquid-liquid junctions involving DCE [43,62,70,71,73], nitrobenzene [67,68,74,75], and nitrophenyloctylether (NPOE) [56]. Various hydrophobic electrolytes have been employed in these solvents. Tetraphenylarsonium (TPAs+) [[71,75,76], bis-triphenylphosphoranylidene (BTPPA+) [43,50], and hydrophobic tetra-arylammonium [77,78] are among the cations used in the organic phase. The choice for anions has been mostly restricted to borate derivatives, tetraphenylborate (TPB ) [70,79,80], tetrakis(4-chlorophenyl)borate (TPBCH) [43,81,82], and tetrakis(penta-fluoro)phenylborate (TPFB ) [49,83], as well as dicarbollyl-cobaltate [75]. 

FIG. 16 Solubility profiles of drugs in solvents with varying dielectric constant s. For curves (a) and (b), see the text. 

When the reaction times for Step 1 are 5 min or longer, the samples severely crack, curl, or dissolve. These results suggest that substantial reaction is occurring in the bulk of the polymer. Significant hydrophilization can occur with reaction times as short as 5 s with RTD concentrations of 0.2-0.5 M. However, 0.002-0.02 M solutions of MeTD or PhTD do not allow sufficient reaction rates for surface hydrophilization at the shorter reaction times. Thus, diffusion of MeTD and PhTD into the polymer must occur readily from the acetonitrile solutions. Acetonitrile was used because it does not swell or dissolve the polymer or RTD-polymer adduct, and the RTDs are soluble and stable in it. This solvent is quite polar (dielectric constant, 38) (25), and this is probably a major factor in the partitioning of the relatively nonpolar RTDs between the polydiene film and the solvent. As noted below, more polar RTDs show less tendency to diffuse into the polymer. 

For hydrophobic, (virtually) nonionizable substances [i.e., those that show no ionic species of significance in the pH range 1 to 10 (e.g., diazepam)], solubility can usually be improved by addition of nonpolar solvents. Aside from solubility, stability is also affected by solvents in either a favorable or a nonfavorable direction [6], Theoretical equations for solubility in water [7] and in binary solvents [8] have been reported in literature, but in general the approach in preformulation is pseudoempirical. Most often the solubility changes as the concentration of nonpolar solvent C2, increases. For binary systems it may simply be a monotonely changing function [9], as shown in Fig. 2. The solubility is usually tied to the dielectric constant, and in a case such as that shown by the squares, the solubility is often log-linear when plotted as a function of inverse dielectric constant, E, that is,... 

Frequently, however, the solubility curve has a maximum (as shown by circles in Fig. 2, when plotted as both a function of C2 and [10]. In either case it is possible to optimize solubility by selection of a solvent system with a given value of s that is, once the curve has been established, the optimum water/solvent ratio for another solvent can be calculated from known dielectric constant relationships [11],... 

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