Estimating Solvent Solubility Parameters

The solvent should have high solubility for the solute being crystallized. The capacity of the solvent to solvate can be quantitatively assessed through its solubility parameter value. Under the like dissolves like paradigm, anon-polar solute is generally more soluble in a non-polar solvent. Hence a solvent with solubility parameter value close to that of the solute can be assumed to have high solubility for the solute. The following empirical equation can be used to estimate the solubility parameter... 

Lin and Nash (1993) have proposed an equation to estimate the Hildebrand solubility parameter of a solute strictly from its mole fraction solubilities and their respective solvent solubility parameters ... 

For the purpose of estimating the solubility of a solute it is necessary to have some measure of the polarity of a solute or a solvent. Based on Eqs. (1) and (2), a useful polarity index should be a measure of a material s intermolecular forces, Cn and C22-Table 1 contains a list of solvents that are typically used in liquid pharmaceutical formulations and three measures of solvent polarity. Each measure of solvent polarity, or polarity index, is based upon a different measure of a material s property. For example, dielectric constant is a measure of the electrical insulating properties of a solvent, solubility parameter is determined from the molar energy of vaporization, and... 

Equation 16.44 can be used in the following way If experimental data for the FH parameter are available, e.g., via chromatographic measurements for a series of systems with the same polymer in different solvents, then from the linear plot depicted by Equation 16.44, the solubility parameter of the polymer can be estimated. Solubility parameters of the solvents are known from direct experimental measurements. Thus, Equation 16.44 represents one of the various indirect methods for estimating polymer solubility parameters. 

Constants obtained by SXLSQI using the data shown in Fig. 7 up to [NaClO lmax. Pitzer parameters [168] and Masson coefficients [2 19] for sodium perchlorate used by SXLSQI were adopted assuming that the low concentration of solvent in the aqueous phase (see Table 11) has negligible effect on the aqueous ionic-activity and ion-volume properties. Solvent solubility parameters used by the program were taken from ref. [153]. Dielectric constants of the water-saturated solvents for use in the Debye-Hlickel treatment used in SXLSQI were 10.57 (TBP [220]), 13.63 (MIBK [221]), 17.5 (MIBC, estimated), and 37.4 (MeN02 [177]) the values for MIBC and MeN02 represent estimates based on an assumption of linear dependence of e on the volume fraction of water in the solvent. 

The authors [91] proposed description of organic phase influence on limiting characteristics of polyurethanearylates (PUAr) interfacial polycondensation. As it is known [55], one from the methods of polymer solubility parameter 5 experimental determination is plotting of the dependence of intrinsic viscosity [t ], measured in several solvents, on this solvents solubility parameter 5 value. The smaller difference 6p-5J or the better solvent thermodynamical quality in respect of polymer is, the larger [q] is. The dependences [q](5 ) have usually belllike shape and such dependence maximum corresponds to 5 [55]. In Fig. 23 the dependence of on 5 of solvents, used as organic phase at PUAr interfacial polycondensation is adduced. The dependence q /S ) bell-like shape is obtained again and its maximum corresponds to 5 10 (cal/cm ), that is a reasonable estimation for PUAr [36, 55]. Let us note that all q values were determined in one solvent, which was not used at synthesis, namely, in mixture phenol-simm-tetrachloroethane. The dependence qj 4(5 ), adduced in Fig. 23, allows to make two conclusions. Firstly, the value q, reached in PUAr interfacial polycondensation process, is controlled by solvent thermodynamical qnality and the greatest... 

There are many methods that can be used to determine the solubility parameter of unknown components. In this study, we estimate the solubility parameter by measuring the solubility in a number of solvents whose 5-values are known. ... 

In short, the rules above can be summarized into one sentence, Like likes Uke . The solubility parameters of common solvents and polymers can be found from the conventional handbooks for physical chemistry or polymers. It is also possible to estimate the solubility parameter of polymers with the method of molar attractive constants according to... 

It is reasonably easy to use Eq. 26 to determine the solubility parameter of a solvent, but since the heat of vaporization of polymers is usually not known, other methods are needed to determine the solubility parameters of polymers. There are several experimental methods, based on polymer swelling measurements or on the determination of the intrinsic viscosity of polymer solutions. Alternatively, solubility parameters can be predicted from knowledge of the chemical structure of each component. The latter method is due to Small (72) and Hoy (73), who supplied values for molar attraction constants (G) of a large number of functional groups (Table 4). The constants G are additive. With these values it is possible to estimate the solubility parameter of any polymer using Eq. 28, where p represents the density and M the molecular weight of the polymer. 

Two solvents were combined to get polycarbonate into solution. How would you estimate the solubility parameter of the solvents when compared with the polymer ... 

Estimates of solubility parameters for a variety of liquids are available in the literature. Table 4.1.6 illustrates the values of solubility parameters for some common liquids. If the solute prefers the solvent (phase 1, species 3), then <5,-is closer to S3 than S, and therefore, X) > 1. (Note Generally, the more polar the liquid, the larger the value of the solubility parameter water, which is highly polar, has a <5,-of 21, whereas n-pentane, which is extremely nonpolar, has a 3i of only 7.1. Further, the higher the required energy of vaporization, the higher the solubility parameter.)... 

Solubility parameters can be determined by direct measurements, indirect calculations, or correlations with other physical parameters. The solubility parameters of solvents usually can be determined directly by measuring the energy of vaporization. The solubility parameters of polymers can only be determined indirectly and may be affected by variations in their chemical constitutions, i.e., the number of crosslinks and the distribution of chain branches or substitutive groups along the polymer backbone. The methods presented in this section can be used to develop correlations of solubility parameters with other physical properties for specific commercial polymer products or to estimate the solubility parameters of new polymers. 

Group contribution methods These methods have been used to estimate the solubility parameter (17,20,28,33,35, 58,60,61,96,112,121,122). van Krevelen (123), Fedors (35), and Barton (12) have reviewed these techniques and given tables of group values. The molar volume of solvents and polymers can also be estimated by group contribution techniques (1 OS). 

Solubility Parameter. CompatibiHty between hydrocarbon resins and other components in an appHcation can be estimated by the Hildebrand solubiHty parameter (2). In order for materials to be mutually soluble, the free energy of mixing must be negative (3). The solubiHty of a hydrocarbon resin with other polymers or components in a system can be approximated by the similarities in the solubiHty parameters of the resin and the other materials. Tme solubiHty parameters are only available for simple compounds and solvents. However, parameters for more complex materials can be approximated by relative solubiHty comparisons with substances of known solubiHty parameter. 

Absorption rates of carbon dioxide were measured in organic solutions of glycidyl methacrylate at 101.3 kPa to obtain the reaction kinetics between carbon dioxide and glycidyl methacrylate using tricaprylylmethylammonium chloride(Aliquat 336) as catalysts. The reaction rate constants were estimated by the mass transfer mechanism accompanied by the pseudo-first-order fast reaction. An empirical correlation between the reaction rate constants and the solubility parameters of solvents, such as toluene, A-methyl-2-pirrolidinone, and dimethyl sulfoxide was presented. 

The polymer-solvent interaction parameter can be estimated by using the solubility parameters for the polymer and solvent. An approximate relationship between these parameters is... 

It is helpful in lc to have a quantitative measure of polarity, so that, for example, the relative polarity of a solvent or a mixture of solvents can be expressed as a number. There are several ways in which this has been done none of them are entirely satisfactory, but they do allow us to arrange solvents in order of polarity and to make rough estimates of the polarity of solvent mixtures. One such way is to use as a measure of polarity a quantity called the solubility parameter, 6, defined by ... 

If Z9b(ai) can be equated with P calculated from the entries in Table 2.5, then Z9b(a2) in any other solvent Ab can be estimated from Eq. (2.62). Equation (2.62) is actually a combination of four expressions of the form of Eq. (2.8) (see section 2.2.2), two for water and solvent Ai and two for water and solvent A2, presuming them to be immiscible pairs of liquids. It employs concentrations on the mole fraction scale, and assumes that the systems behave as regular solutions (which they hardly do). This eliminates the use of the solubility parameter 8 of water, which is a troublesome quantity (see Table 2.1). Solvent Ai need not, of course, be 1-octanol for Eq. (2.62) to be employed, and it suggests the general trends encountered if different solvents are used in solvent extraction. 

Thus from solubility parameters, which are specific for the various solutes and solvents, and molar volumes, values for can be estimated, or deviations from regularity can be assessed. These deviations can be estimated quantitatively and, in individual systems, can be ascribed to specific reactions in either of the phases, e.g., hydration, solvation, adduct formation, etc. 

Note 4 The solubility of a substance B can be related to the square of the difference between the solubility parameters for supercooled liquid B and solvent at a given temperature, with appropriate allowances for enbopy of mixing. Thus a value can be estimated from the solubility of the solid in a series of solvents of known solubility parameter. 

Finally, the solubility parameter of the adhesive and the substrate must be close. Without getting too teehnieal, the solubility parameter is a rough estimate of polarity. The old saying like dissolves like can be extended to like bonds like. More aeeurately, the solubility parameter is the ealeulated potential energy of 1 em of material for eommon solvents. Polymers are assigned solubility parameters of solvents in which they are soluble. Table 19.3 lists solubility parameters for various solvents and polymers. As an example of how to use this table, butadiene-acrylonitrile rubber with 6= 9.5 bonds natural rubber (6= V.9-8.3) to phenolic plastics (6= 11.5). Note that its solubility parameter is between that of the two substrates. 

The selection of a solvent for a new separation problem, even today, is a matter of trial and error. The application of theory (2) with the additional application of the solubility parameters (6J-65) makes it possible to estimate the composition of appropriate solvent mixtures for the separation of relatively simple compounds. In order to calculate the necessary solvent strength, however, a set of experimental data concerning the behavior of the sample components, the adsorbent, and the elution strength of the eluents with the specific adsorbent are necessary. Others (J5) recommend a graphical method as a time-saving alternative to bi th calculation and the trial-and-error approach to obtain a first approximation of the eluent composition appropriate for the separation of a givin sample. 

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