Cyclohexane 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. ... 

Consequentely, we have chosen solvents in order to change separately either the norm of the solubility parameter or its direction (see Fig. 4). These solvents are listed in Table 1. It can be clearly seen that the polar and hydrogen bonding interactions are zero for all of the aliphatic and cycloaliphatic alkanes. This allows one to change only the value of without changing its direction. For a second series of experiments, we compare 2,6-dimethyl-4-heptanone, dib-utylether and methyl-cyclohexane which have nearly identical lengths, but different vector directions. 

The differences in the master curves for log Ep(t) vs. log t obtained from Kraton 102 specimens cast from benzene, cyclohexane, and tetra-hydrofuran solutions may be caused by differences in the composition or the morphology of the phases. Beecher et al. (2) have emphasized the role of solvent in determining the phase structure of cast block copolymer films. At 25°C the solubility parameters for the polymers (3) and solvents (I) are Material Solubility Parameter... 

FIGURE 2.2 Regularsolutiontheory plotfor hydrocortisone solubility data. The curve represents thesolubility predicted by Equation 2.41 using data frorhexane, cyclohexane, carbon tetrachloride, toluene, and benzene to estimate the solubility parameter of hydrocortisone. (Data taken from Hagen, T. A. 1979. With permission of the author.)... 

As shown In Figure 4, the rate of polymerization of styrene was retarded by good nonvlscous solvents such as benzene, cyclohexane, and octane whose solubility parameters (6) were within 1.5H of that of polystyrene at styrene to additive ratios of 3 to 1. The absolute rates were slightly Increased In poorer nonvlscous solvents such as heptane and hexane and were fastest In viscous nonsolvents such as dllsoctyl phthalate and Nujol. Rate studies Indicated a Rp dependency on [E] substantially greater than unity for the styrene emulsion systems modified with viscous poor solvents. 

The oil structure influence on the formulation is illustrated in Figure 1. It represents the minimum percentage of emulsifiers required to induce the transition aacro-raicroeaulsion versus their HLB values for monomer-water mixtures dispersed in different oils. It can be seen that in the case of acrylamide (AH) or acrylamide-sodium acrylate (Aa) mixtures, the amount of surfactant needed to form a microemulsion is much larger for toluene or cyclohexane than for Isopar K (11,12[). When methacrylcxyethyltrimethylammonium chloride (HA0OU.AT) is the monomer, the optimal conditions are obtained in cyclohexane. These results closely follow the differences calculated for the solubility parameters between oils and lipophiles as shown in Table I. 

Ray SK, Sawant SB, Joshi JB, and Pangarkar VG. Development of new synthetic membranes for separation of benzene-cyclohexane mixtures by pervaporation A solubility parameter approach. Ind. Eng. Chem. Res. 1997 36(12) 5265-5276. 

The static mode uses both organic solvents such as toluene [27], methanol [28] or acetone [29] and solvent mixtures (usually in a 1 1 ratio) including dichloromethane-acetone [20,28], acetone-hexane [30,31], heptane-acetone [31], acetone-isohexane [32] or methanol-water [33], The use of mixed solvents as extractants provides improved extraction in terms of expeditiousness and recovery [20,28,30-35] as a result of the solubility parameter for a binary mixture being roughly proportional volumewise to the parameters of its components [36], Thus, in the extraction of Irganox 1010 from polypropylene, the addition of 20% of cyclohexane to 2-propanol doubles the extraction... 

Frank et aL reported examples of quickly screening solvents for organic solids. In one particular example, solubilities of aspirin in four different solvents (acetone, ethanol, chloroform, and cyclohexane) were used to regress the Hansen solubility parameters for the solute, aspirin. Once the Hansen solubility parameters are identified for aspirin, Frank et al. showed that one could quickly estimate the solubilities of aspirin in any solvent or solvent mixture as long as the Hansen solubility parameters are also available for the solvents. 

Elliott and Lira show that ajb 8, where d is the solubility parameter. For large molecules, the solubility parameter varies little with respect to molecular weight. Thus, increases in C correspond primarily to increases in cohesive energy density, not molecular size. Taking pentane as an example of component 1, we can estimate ( from solubility parameters to be 0.16, 0.27, 0.33, 0.40, 0.52, 0.62, 0.84 for cyclohexane, benzene, acetone, n-hexanol, ethanol, methanol, and water. This provides an idea of the range of chemical functionalities addressed in Fig. 4. 

A pump capable of several thousand p.s.i. commonly is used. Not only is the pump needed to maintain supercritical conditions, but the solubilizing power of the system varies greatly with pressure, usually dissolving more solutes as the pressure increases. For example, COj at 1.23 g/em will dissolve eompounds with Hildebrand s solubility parameter (Chapter 41, p. 479) from 7-10, about the same as benzene, chloroform, ethyl acetate, acetone, cyclohexane, carbon tetrachloride, toluene, ethyl ether, and pentane. If the pressure is reduced so that the COj is about 0.9 g/cm then it will dissolve compounds with parameters from 7-9 (solvents like cyclohexane, carbon tetrachloride, toluene, ethyl ether, and pentane) and if further lowered to 0.6 g/cm, it will dissolve only compounds with parameters of 7-8 (ethyl ether and pentane). 

In these equations the vapor compositions, vb and yc. and the equilibrium pressure P are unknown (the equilibrium pressure is 1.013 bar only at xb — 0.525). The solution is obtained by choosing a value of xg, using xc = 1 — xb, and copiputing ys and yc from Eqs. i, and the total pressure from Eq. iii. The vapor-phase mole fractions are then computed from Eqs. ii. The results of this calculation are given in the table and Fig. 2. Regular solution model. Since benzene and cyclohexane are nonpolar, and their solubility parameters are given in Table 9.6-1, the activity coefficients can be predicted using Eqs. 

It is also interesting to note that, although polypropylene will not dissolve directly into cyclohexane at room temperature despite the great similarity in solubility parameter, 9.2 as compared with 9.4 cal g, solutions can be prepared by dissolving it first in decalin at 140°C, cooling and then diluting with cyclohexane [9]. The system is miscible in all proportions and SEC can be carried out on the solutions. 

Examine with the help of the regular solution theory, UNIFAC and modified UNIFAC if the binary systems benzene-cyclohexane and benzene-n-hexane show an azeotropic point at 80 C. In case of the regular solution theory, calculate the solubility parameter from the saturated liquid density and the heat of vaporization using Eq. (5.70). All required data are given in Appendices A, H, and 1. 

The influence of oil characteristics on formulation is illustrated in Fig. 6.3. This shows the minimal quantity of surfactants required to induce the macro-to microemulsion transition, as a function of their HLB values. The curves represent various water/monomer mixtures dispersed in different organic solvents. We see that in the case of acrylamide, the quantity of surfactants required to form a microemulsion is much greater for toluene or cyclohexane (65% and 47%, respectively, for an HLB value of 8.85) than for isopar M (9%). When the monomer is MADQUAT, optimal conditions are obtained in cyclohexane. This influence of the nature of the solvent on its aptitude in forming microemulsions precisely reflects the mismatch we can calculate between lipophile and oil solubility parameters (5l = 7.87 Hildebrand, isopar = 7.79 Hildebrand, (( toluene = 8.88 Hildebrand). 

The two monomers of major interest, styrene and ethylene, are well known and details can be found on all aspects of their technology elsewhere. Poly(ethylene-co-styrene) is primarily produced via solution polymerization techniques using metallocene catalyst/co-catalyst systems, analogous to the production of copolymers of ethylene with a-olefin monomers. Solvents that can be employed include ethyl-benzene, toluene, cyclohexane, and mixed alkanes (such as ISO PAR E, available from Exxon). The thermodynamic properties of poly(ethylene-co-styrene), including solvent interactions and solubility parameter assessments, are important factors in relation to polymer manufacture and processing, and have been reported by Hamedi and co-workers (41). 

FIGURE 3.4 Evaporation of a mixture of acetone and cyclohexane at 25°C. If a mixture of acetone-cyclohexane (50 50) is allowed to evaporate, the vapour that comes off will have a composition of = 69 31, i.e. acetone will evaporate preferentially. This progressively changes the composition of the mixture until, at 74% acetone, the vapour that comes off is also 74% acetone. This constant evaporation mixture will then evaporate until dry. Similarly if one starts with a mixture of acetone-cyclohexane (90 10), the v our that comes off will have a composition of = 83 17, i.e. cyclohexane will evaporate preferentially until the azeotropic composition of 74% acetone is reached. The change of solubility parameters of the solvent will affect the stability, viscosity, etc. of a polymer solution. Azeotropes are usually described as constant boiUng mixtures, but their behaviour at room temperature is more important for conservators. There are fewer published details of the mixtures at room temperature. The effect of the dissolved polymer on the relative evaporation rates has yet to be elucidated. 

The best fit of the experimental data gives two very similar curves the maximum in these curves occurs with the best solvent, which is cyclohexane for 100% cis PTBA and a solvent with 6 between cyclohexane and methylcyclohexane for cis/trans PTBA. Generally, it is assumed that the polymer has the same solubility parameter as that of the best solvent (19,22). Therefore, Sptba values deduced from our experiments are almost the same for the two samples 16.8 MPa for the 100% cis sample and 16.3 MPa for the cis/trans PTBA sample. These data are in very good... 

In a paper by Bradford and Thodos (1966), 4 of the 16 references are to Hildebrand et ai, one to Chao and Seader, one to Prausnitz and Edmister, one to Frost and Kalkwarf, and the remainder to Thodos and his colleagues. The solubility parameter 5 is a temperature-dependent quantity, and when we are dealing with the difference between the 5a and 5s values, we are presented with differential effects. It was pointed out by the authors that the 5 value at 25°C has been assumed to be the same for other temperatures for utility purposes and represents a fictitious or empirical value. Data for n-hydrocarbons from methane to dodecane and for ethylene, propylene, 1,3-butadiene, cyclohexane, and benzene were given. 

The role of solvents is to reduce the viscosity of adhesives and to improve fluidity. That can provide the adhesives wettability to create an intimate contact with the surface of adherends. Solvents must be able to dissolve the components of adhesives. Solubility parameter is an index to show the soliditivity of solvents. A solvent can dissolve a high amount of materials whose solubility parameters are close to that of the solvent. Water, alcohols, aromatic hydrocarbons (e.g., toluene and xylene), ketones (e.g., methyl ethyl ketone and cyclohexanone), acetate esters (e.g., ethyl acetate and butyl acetate), n-hexane, cyclohexane, methylene chloride are used due to their solubility, dehydration rate, noncombustibility, and workability. To meet the demands concerning environmental issues, the use of some solvents such as toluene, xylene, ethylbenzene, and styrene is restricted bylaws such as the air pollution control law legislated by Ministry of the Environment in Japan (The Ministry of the Environment 1996). 

Therefore, for At = 10 g/mol, = 3.56, that is, the individual polymer molecules occupy almost 4 times the volume in cyclohexane than they do in any theta solvent. It was mentioned in Section 2.5 that polymers in contact with solvents of like solubility parameter 5 should show the greatest solvation effects, that is, swelling of networks or enhancement of viscosity of solutions. Now we can identify this solvating ability with a, the expansion factor. 

Polyisobutylene is readily soluble in nonpolar Hquids. The polymer—solvent interaction parameter Xis a. good indication of solubiHty. Values of 0.5 or less for a polymer—solvent system indicate good solubiHty values above 0.5 indicate poor solubiHty. Values of X foi several solvents are shown in Table 2 (78). The solution properties of polyisobutylene, butyl mbber, and halogenated butyl mbber are very similar. Cyclohexane is an exceUent solvent, benzene a moderate solvent, and dioxane a nonsolvent for polyisobutylene polymers. 

The next question is, what physicochemical parameters may influence the adsorption-desorption equilibrium We suspected that the difference with different solvents may be due to the fact that the solubilities of cinchonidine in different solvents are different, so we tested the solubilities of cinchonidine in 54 solvents, and found that if the initially established adsorption-desorption equilibrium is perturbed, that is beeause the solubility of einehonidine in that flushing solvent is relatively big (e.g., 12 g/L in diehloromethane). On the other hand, the adsorption-desorption equilibrium is not perturbed by cyclohexane, because the solubility of cinchonidine in cyclohexane is quite small (0.46 g/L). By plotting the measured cinchonidine solubility versus solvent polarity reported in the literature, nice volcano-like correlations ean be identified (Figure 18) [66]. This example shows that some empirical observations in enantioselective hydrogenation may be traeed baek to basie physieoehemieal properties sueh as the solubility of cinchonidine and the polarity of the solvent. 

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