Pyridine solubility parameter

FIGURE 3 2 Solvent extraction efficiencies (EF) as functions of dielectric constants (D), solubility parameters (6), and polarity parameters (P and E -). Solvents studied silicon tetrachloride, carbon disulfide, n pentane. Freon 113, cyclopentane, n-hexane, carbon tetradiloride, diethylether, cyclohexane, isooctane, benzene (reference, EF 100), toluene, trichloroethylene, diethylamine, chloroform, triethylamine, methylene, chloride, tetra-hydrofuran, l,4 dioxane, pyridine, 2 propanol, acetone, ethanol, methanol, dimethyl sulfoxide, and water. Reprinted with permission from Grosjean. ... 

The extent to which these Flory interaction parameters apply to the pyridine-insoluble portion of the Illinois No. 6 coal is open to question. We cannot address this aspect fully here, but we have noted that the pyridine-soluble and -insoluble portions of the Illinois No. 6 coal studied here have similar carbon, hydrogen and oxygen contents. Maciel has observed that the aromaticities of the two portions of an Illinois No. 6 coal are similar as well.(12) Based on this alone, it seems that the pyridine-soluble portion is representative of the larger, crosslinked portion, at least for the Illinois No. 6 coal, but this aspect remains controversial,(12) so caution is warranted. 

Table A. Analytical Data and Structural Parameters of the Pyridine-Soluble, Benzene-Insoluble Part of a Vitrinite and the Corresponding Pyridine-Insoluble Residue After THQ Treatment Compared with Those of the Starting Materials...

Solubility of the three commercial polysulfones follows the order PSF > PES > PPSF. At room temperature, all three of these polysulfones as well as the vast majority of other aromatic sulfone-based polymers can be readily dissolved in a few highly polar solvents to form stable solutions. These solvents include NMP, DMAc, pyridine, and aniline. 1,1,2-Trichloroethane and 1,1,2,2-tetrachloroethane are also suitable solvents but are less desirable because of their potentially harmful health effects. PSF is also readily soluble in a host of less polar solvents by virtue of its lower solubility parameter. 

Further evidence of the importance of the physical nature of the solvent is found in the work of Belssing and Ross (6) who correlated the coal conversion (pyridine solubles) with the Hildebrand solubility parameter, 6, which they defined as... 

The above forced flow procedure was employed to determine trace element content in six additional pyridine soluble SRC s. Each SRC differs from another in either raw coal source, conversion severity (i.e. pressure-temperature), added Na2C03 content or method of residue removal. Table III outlines the various processing parameters and the assigned run number. The measured elemental concentrations are listed in Table IV. 

FIGURE 3 The dependences of macromolecular coil fractal dimension on polymer and solvent solubility parameters difference A5 for copolymers SAN-MMA. The solvents 1— toluene, 2—ethyl benzene, 3— benzene, 4—chlorobenzene, 5—chloroform, 6—tetrahydrofuran, 7—pyridine, 8—methyl ethyl ketone, 9-1,4-dioxane, 10—N, N-dimethylformamide. The same conventional signs are used in Figs. 4-11. 

Certain solvents stand out as being unusually effective, pyridine and ethylenediamine being the most noteworthy. They are not uniqne, however, and any solvent having a Hildebrand solubility parameter of 11 and the capacity to serve as an effective hydrogen bond acceptor will be a... 

Solubility of the three commercial polysulfones follows the order PSF > PES > PPSF. At room temperature, all three of these polysulfones as well as the vast majority of other aromatic sulfone-based polymers can be readily dissolved in a handful of highly polar solvents to form stable solutions. These powerful solvents include NMP, DMAc, pyridine, and aniline. 1,1,2-Trichloroethane and 1,1,2,2-tetrachloroethane are also suitable solvents but are less desirable because of their potentially harmful health effects. In addition to being soluble in the aforementioned list, PSF is also readily soluble in a host of less polar solvents by virtue of its lower solubility parameter. These solvents include tetrahydrofuran (THF), 1,4 dioxane, chloroform, dichloromethane, and chlorobenzene. The relatively broad solubility characteristics of PSF have been key in the development of solution-based hollow-fiber spinning processes in the manufacture of polysulfone asymmetric membranes (see Membrane Technology). The solvent list for PES and PPSF is short because of the propensity of these polymers to undergo solvent-induced crystallization in many solvents. When the PES structure contains a small proportion of a second bisphenol comonomer, as in the case of RADEL A (British Petroleum) polyethersulfone, solution stability is much improved over that of PES homopolymer. 

A solubility parameter of 24.5-24.7 MPa / [12.0-12.1 (cal/cm ) ] has been calculated for PVF using room temperature swelling data (52). The polymer lost solvent to evaporation more rapidly than free solvent alone when exposed to air. This was ascribed to reestablishment of favorable dipole-dipole interactions within the polymer. Infrared spectral shifts for poly(methyl methacrylate) in PVF have been interpreted as evidence of favorable acid-base interactions involving the H from CHF imits (53). This is consistent with the greater absorption of pyridine than of methyl acetate, despite a closer solubiUty parameter match with methyl acetate. 

Frequently it is necessary to combine materials having quite dissimilar solubility parameters, and often differing in modulus as well. An important example, the manufacture of tires, is discussed in the chapter, Bonding Textiles to Rubber. Use is made of a hybrid adhesive, RFL, containing heat-resistant resorcinol-formaldehyde for good attachment primarily to the polar, high modulus fiber, plus an elastomer of moderate solubility parameter, butadiene-styrene-vinyl pyridine terpolymer latex, mainly for the rubber. 

Oele et al. (l2l) classified the solvents into five groM s with respect to their effect on coal. The three gro 5>s that are of interest in liquefaction practice are the specific solvents (e.g. pyridine), degrading solvents (e.g. anthracene), and reactive solvents (e.g. tetralin). Dryden (l22) suggested to Tise the square of the solubility parameter in correlating solvent effectiveness. The solubility parameter is a measure of the cohesive forces in a solution that has no excess entropy of mixing (l23). Silver and coworker, based on Kiebler s data (l ), found that solvents with a nonpolar solubility parameter of 9.5 (cal/c.c.) appeared to be most effective for coal dissolution (12 ). 

To assess the applicability of the modules in Materials Studio 4.2 that are relevant for this application, the COMPASS force field [25] was chosen as currently implemented in the Forcite molecular simulation engine. To test the accuracy of densities calculated in these atomistic simulations, benchmark calculations were performed for some experimentally weU-characterized traditional solvents either with some structmal similarity to the imidazolium cation (pyridine, methylimidazole) or for some specifically selected value of the solubility parameter components as will be shown later (CSj, formamide). The results of the simulations (which used 20 solvent molecules and followed the protocol described above) are presented in Table 5.1. 

Unavailable because experimental methods for estimation of this parameter for pyridines are lacking in the documented literature. However, its high solubility in water and low Kow suggest its adsorption to soil will be nominal (Lyman et al., 1982). 

The swelling data in Table IV can be used to calculate x parameters for the extract and O-methylated extract using Equation 1. The results are shown in Table V. The x parameters for both extracts are observed to be positive and independent of pressure or concentration of benzene. The magnitude of the parameters are much larger than that determined for the O-octylated extract (0.65) which is consistent with their lower solubilities in liquid benzene. The X parameters are much larger than those determined by Larsen el al. for the pyridine-extracted Illinois No. 6 coal, which was near 0.3.(6) The reason for this are not clear. However, we note that benzene is a very poor solvent for these pyridine-extracts so large x parameters are expected. 

Solvatochromic Approach Solvatochromic relationships are multivariate correlations between a property, usually solubility or partitioning property (see Sections 11.4 and 13.3), and solvatochromic parameters, parameters that account for the solutes interaction with the solvent. In the case of vapor pressure, the solvatochromic parameters only have to account for intermolecular interaction such as selfassociation between the solute (i.e., pure compound) molecules themselves. The following model has been reported for liquid and solid compounds, including hydrocarbons, halogenated hydrocarbons, alkanols, dialkyl ethers, and compounds such as dimethyl formamide, dimethylacetamide, pyridine, and dimethyl sulfoxide... 

Moreover, as has been recognized, pyridine is strongly hydrogen bonded in protolytic media (hence, for example, its high water solubility). Such hydrogen bonding substantially reduces the reactivity toward electrophiles, and as a consequence reactivity parameters determined for the free base in solution in H-donor solvents differ markedly from those determined in the gas phase. This difference is —0.3 ct units at each position. 

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