Miscible solutions

Tetraethyl orthosilicate (104.2 g) and deuterium oxide (40 g) are stirred in a stoppered distillation flask at room temperature until a viscous, miscible solution is obtained (approximately 24 hr). (A small amount of acid catalyst, such as deuteriochloric acid, speeds up the reaction considerably. ) A distillation head and a receiver cooled in a dry ice-acetone bath are attached and the solution is distilled at 2 mm pressure until no further product is obtained. A 90% yield of ethanol-OD is obtained having an isotopic purity equal to that of the deuterium oxide used. ... 

Figure 4. Left side Miscible Solution of THF/water at 1 bar. Right side phase separation at 30 bar CO2. The partition coefficient of the water-soluble dye is greater than 10 (14)...

PAr is soluble in similar polar organic solvents (e.g., NMP, DMAc, DMSO, etc.) which dissolve PBI. It was observed that miscible solution blends of PBI and PAr could be formed. For example, NMP dopes containing 10 wt % PBI and PAr are visually homogeneous and contain no insolubles as formed. After being kept at room temperature for a period of time (e.g., several days), a PBI-rich phase starts to form precipitate, but this polyphasic material can be easily redissolved into a single phase with a mild heating (i.e., 100 °C for 20 min). Based on the haze level, the stability of the PBI/PAr/NMP solutions appeared to increase with the increase of the relative PAr concentrations. 

Endosmosis. The diffusion which proceeds through.a semi-permeable membrane, separating two miscible solutions, and tends to equalize their concentrations. The chief movement of solvent toward the denser solution (endosmosis) usually masks the slower diffusion (exosmosis) in the opposite direction. 

For effective catalytic hydrolysis of lipophilic phosphate esters in aqueous solution, metallomicelles such as 3 [21], 4 [22], 5 [23], 6 [24], 7 [25], and 8 [26] have been designed (Scheme 3). These complexes are essentially metal ions chelated with ligands that are attached with lipophilic long alkyl chains. Some of these were used together with surfactants to make water-miscible solutions. 

The aim of developing a new polymer blend is to synergistically combine the properties of the individual polymers resulting in an improved material. A general precondition to this scheme of fabrication, however, is that in order for the final blended material to have the desired properties, the final polymeric phases must form a heterophasic blend, i.e., they must have at least partial thermodynamic immiscibility. This is in contrast to the requirement that the initial reactants must form initially miscible solutions. These conditions do not seem to be met by most polyimide-epoxy systems. 

Because the components must initially form miscible solutions or swollen networks a degree of affinity between the reacting components is needed. Therefore, most of the investigations into epoxy IPNs have involved the use of partially miscible components such as thermoplastic urethanes (TPU) with polystyrenes [57], acrylates [58-61] or esters which form loose hydrogen-bound mixtures during fabrication [62-71 ]. Epoxy has also been modified with polyetherketones [72],polyether sulfones [5] and even polyetherimides [66] to help improve fracture behavior. These systems, due to immiscibility, tend to be polymer blends with distinct macromolecular phase morphologies and not molecularly mixed compounds. 

Consider a system consisting of a completely miscible solution of solute and solvent in all proportions. One should consider dissolution of solids in liquids as occurring... 

The complete miscible solution will be obtained when the temperature of the solution is >Tm. Equation (3.36b) indicates that any solute having a solubility parameter ranging from 15.1 to 27.1 will be completely miscible with octanol at 25°C. The molar solubility of the liquid solute in octanol is equal to ... 

In liquid-liquid extraction (Fig. 3.6) two miscible solutes are separated by a solvent, which preferentially dissolves one of them. Close-boiling mixtures that cannot withstand the temperature of vaporization, even under vacuum, may often be separated by this technique. Like other contact processes the solvent and the mixture of solutes must be brought into good contact to permit transfer of material and then separated. The extraction method utilizes differences in the solubility of the components in the solvent. 

Many patents 81 95 and papers 45 96 104) deal with thermal polymerization. In the case of diene monomer polymerizations (partially miscible solutions yielding oligomers of Mn 500 and polymers of Mn = 1500-11000), or vinyl acetate polymerization (fully miscible solutions yield polymers of Mn = 500-4000) the dependence of yield, polydispersity and functionality has been studied in dependence on various reaction parameters (temperature, time, solvent, etc.). 

The above derivation is not restricted to just miscible solutions. It holds equally well for any other two-phase mixture, including liquid solutions in equilibrium with solid solutions, or, more importantly, to a liquid solution in equilibrium with a pure solid component (such as ice immersed in a salt solution). In that case x. = 1 refers to the pure component and we obtain... 

Properties Reddish brown solid with a mild ester odor. Bp 125C. Soluble in water and alcohol almost insoluble in kerosene and diesel fuel. Commercially available as a water-miscible solution. 

Under aqueous conditions, the concentration of hydrogen ion in solution is usually expressed in terms of the hydrogen ion concentration or activity, or in terms of pH units. The pH of a non-aqueous solution or co-solvent solution is more difficult to measure, since pH only relates to purely aqueous conditions. The pH of a water miscible solution can be measured with an electrode, however interpretation of the pH value must be done with care. 

Henry s law is mainly valid at low concentrations of the solute, typically below 1%, and is therefore applicable to low miscibility solutes. By extension, the solutes are not limited to non-condensables but could include condensables with low miscibility. 

Cholesterol and lecithin form completely miscible solutions in mono-layers at very low surface pressures, characterized by excess positive heats and excess negative areas of mixing. At elevated surface pressures, phase separation occurs. Since these solutions conform to regular solution theory, the hydrocarbon domain of the monolayer makes the major contribution to the heats of mixing. The polar region of the monolayer may... 

FIGURE 4.4 Gibbs energy of a partially miscible solution at a constant [T,p. ... 

To extend the activity-coefficient equation to partially miscible solutions, Renon and Prausnitz [8] introduced a factor to the exponential energy term in Wilson s equation. With a < 1, the effect is to suppress the preferential attraction of molecules to the central molecule. The local mole fraction of component 2 about component 1 in a binary solution is given by... 

Comparison with experimental data shows that the complete local-composition equation preserves the quality of Wilson s equation in describing vapor-liquid equilibrium of completely miscible systems. There are no more than slight differences between the complete equation and Wilson s equation in the fitting of data. But the complete local-composition (CLC) equation extends Wilson s local-composition equation to partially miscible solutions. Good predictions of the coexistent liquid compositions of ternary mixtures based on the binary parameters have been found for water + ethyl acetate + ethanol, for water + methyl acetate + acetone, and for water + acrylonitrile + acetonitrile. 

The UNIQUAC equation, based on the name UNlversal QUAsi Chemical, is applicable to liquid solutions of hydrocarbons, alcohols, nitriles, ketones, aldehydes, organic acids, and water. Partially miscible solutions are represented. The two interaction parameters are determined by htting binary-solution data, and the equations are useful for binary as well as multicomponent solutions. 

When miscible solutions of different concentration are separated by a membrane that is permeable to the solvent but nearly impermeable to the solute, diffusion of solvent occurs from the less concentrated to the more concentrated solution, where the solvent activity is lower. The diffusion of solvent is called osmosis, and osmotic transfer of water occurs in many plant and animal cells. The transfer of solvent can be stopped by increasing the pressure of the concentrated solution until the activity of the solvent is the same on both sides of the membrane. If pure solvent is on one side of the membrane, the pressure required to equalize the solvent activities is the osmotic pressure of the solution rt. If pressure higher than the osmotic pressure is applied, solvent will diffuse from the concentrated solution through the membrane into the dilute solution. This phenomenon is called reverse osmosis, because the solvent flow is opposite to the normal osmotic flow. 

If it is desired to assess the relative extent of drug absorption from a product, the total area under the plasma concentration from the product to that obtained for a reference drug standard is compared. The reference standard may be an intravenous injection, an orally administered aqueous or water-miscible solution, or another product accepted as a standard. 

The first reported example using macromolecule-supported catalysts in latent biphasic systems was work by Chan s group that employed a dendrimer-bound BINAP 127 that was used to form a chiral ruthenium hydrogenation catalyst [164]. The dendritic Ru-BINAP complex formed from the reaction of [RuCl2(benzene)2]2 and 127 was successfully used in four cycles in the hydrogenation of 2-phenylacrylic acid (Eq. 65) in a 1 1 (vol/vol) ethanol/hexane mixture. Addition of 2.5 vol% water to this mixture produced a biphasic mixture where >99% of the dendritic catalyst was in the hexane phase. Addition of a fresh ethanolic substrate solution to this hexane phase produced another miscible solution of catalyst and substrate. The second and subsequent cycles of hydrogenation carried out in this manner led to consistent conversions of substrate with synthetic yields of >91% with e.e. values of 90%. 

Liquids meeting the definition in 2.3.1.1 with a flash point of more than 35 C which do not sustain combustion need not be considered as flammable liquids for the purposes of these Regulations. Liquids are considered to be unable to sustain combustion for the purposes of these Regulations (i.e. they do not sustain combustion under defined test conditions) if (a) They have passed a suitable combustibility test [text continues] (b) Their fire point according to ISO 2592 1973 is greater than 100°C or (c) They are water miscible solutions with a water content of more than 90% by mass. UN 2.3.1.2... 

For the purpose of subsection 1.1.2, liquids are not considered to sustain combustion if . 1 they have passed the combustibility test (see Chapter 5 of the United Nations Recommendations on the Transport of Dangerous Goods) or. 2 their fire point according to ISO 2592 is greater than 100°C or. 3 they are miscible solutions with a water content of more than 90% by mass. IMO Class 3,1.1.3... 

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