Partially miscible organic solvent

In the isolation of organic compounds from aqueous solutions, use is frequently made of the fact that the solubility of many organic substances in water is considerably decreased by the presence of dissolved inorganic salts (sodium chloride, calcium chloride, ammonium sulphate, etc.). This is the so-called salting-out effect. A further advantage is that the solubility of partially miscible organic solvents, such as ether, is considerably less in the salt solution, thus reducing the loss of solvent in extractions. 

Coyle, G.T., Harmon, T.C., andSuffet, I.H. Aqueous solubility depression for hydrophobic organic chemicals in the presence of partially miscible organic solvents, Environ. Sci. Technol, 31(2) 384-389, 1997. 

We conclude this section with some brief comments on the cosolvent effects of partially miscible organic solvents (PMOSs). These solvents include very polar liquids such as w-butanol, w-butanone, w-pentanol, or o-cresol, but also nonpolar organic compounds such as benzene, toluene, or halogenated methanes, ethanes, and ethenes. For the polar PMOS, a similar effect as for the CMOS can be observed that is, these solvents decrease the activity coefficient of an organic solute when added to pure water or to a CMOS/water mixture (Pinal et al., 1990 Pinal et al., 1991 Li and Andren, 1994). For the less polar PMOS there is not enough data available to draw any general conclusions. 

Partially water-miscible organic solvents (PMOSs) may act as either cosolvents or cosolutes, and the research in the past has shown flic complexity of their effects. " It was demonstrated that in order to exert effects on solubility or sorption of HOCs, PMOSs must exist as a component of the solvent mixture in an appreciable amount Munz and Roberts suggested a mole fi action of greater than 0.005 and Rao and coworkers proposed a volume percent of 1% or a concentration above lO mg/L. Cosolvents with relatively high water solubility are likely to demonstrate observable effects on the solubilities of solutes, up to their solubility limits, in a similar manner to cosolvents of complete miscibility with water. A few experimental examples of the effects of PMOSs include 1 -butanol and... 

It is generally observed that partial substitution of water miscible organic solvents (like ethanol) into the aqueous phase results in increased extraction (or sorption), and. 

Organic solvent (partially water miscible) Organic solvent (immiscible with water) Organic solvent (miscible with water)... 

Cationics may be titrated with tetraphenylborate in a single aqueous phase using 2,7-dichlorofluorescein as indicator (101). Dichlorofluorescein forms a complex with quaternary compounds, which dissociates, with a color change from pink to yellow, when the end point of the titration is reached. Since this is a precipitation reaction, alcohols and other water-miscible organic solvents must be avoided since they partially dissolve the precipitate and spoil the end point. By adjustment of pH as described above, the procedure may be used for the determination of amines other than quaternaries. 

Di-alkyl ethers of ethylene glycol, ROCHjCHjOR. The dimethyl ether, b.p. 85°/760 mm., is miscible with water, is a good solvent for organic compounds, and is an excellent inert reaction medium. The diethyl ether (diethyl cdloaolve), b.p. 121-57760 mm., is partially miscible with water (21 per cent, at 20°). 

Bonhote and co-workers [10] reported that ILs containing triflate, perfluorocar-boxylate, and bistrifylimide anions were miscible with liquids of medium to high dielectric constant (e), including short-chain alcohols, ketones, dichloromethane, and THF, while being immiscible with low dielectric constant materials such as alkanes, dioxane, toluene, and diethyl ether. It was noted that ethyl acetate (e = 6.04) is miscible with the less-polar bistrifylimide and triflate ILs, and only partially miscible with more polar ILs containing carboxylate anions. Brennecke [15] has described miscibility measurements for a series of organic solvents with ILs with complementary results based on bulk properties. 

The PBE dendron has a glass transition at about 40 °C and is soluble in various organic solvents (e.g., THF, acetone, toluene). It is therefore a moldable, thermoplastic, film-forming material. This practical feature is maintained for the lanthanide-cored dendrimer complexes. The complexes are partially miscible with poly(methyl methacrylate), affording transparent luminescence compositions by mixing in solvent. 

An interface between two immiscible electrolyte solutions (ITIES) is formed between two liqnid solvents of a low mutual miscibility (typically, <1% by weight), each containing an electrolyte. One of these solvents is usually water and the other one is a polar organic solvent of a moderate or high relative dielectric constant (permittivity). The latter requirement is a condition for at least partial dissociation of dissolved electrolyte(s) into ions, which thus can ensure the electric conductivity of the liquid phase. A list of the solvents commonly used in electrochemical measurements at ITIES is given in Table 32.1. 

Using Nile Red, the polarity of several ionic liquids has been found to be comparable to that of lower alcohols. Figure 4.4 summarizes the polarity data for some ionic liquids with comparisons to common organic solvents (the structure of Nile Red is shown in Chapter 1). Polar organic solvents like dichloromethane and diethyl ether are miscible with ionic liquids, whereas solvents of low polarity show partial miscibility and nonpolar solvents are essentially immiscible. 

Solutes have differing solubilities in different liqnids dne to variations in the strength of the interaction of solnte molecnles with those of the solvent. Thus, in a system of two immiscible or only partially miscible solvents, different solutes become unevenly distribnted between the two solvent phases, and as noted earlier, this is the basis for the solvent extraction technique. In this context, solvent almost invariably means organic solvent. This uneven distribution is illustrated in Fig. 1.3, which shows the extractability into a kerosene solution of the different metals that appear when stainless steel is dissolved in aqueous acid chloride solution. The metals Mo, Zn, and Fe(III) are easily extracted into the organic solvent mixture at low chloride ion concentration, and Cu, Co, Fe(ll), and Mn at intermediate concentration, while even at the highest chloride concentration in the system, Ni and Cr are poorly extracted. This is used industrially for separating the metals in super-alloy scrap in order to recover the most valuable ones. 

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