Two-liquid phase systems

TIPSH (0.25 mol) was added to a mixture of anhydrous copper(n) chloride (0.55mol) and MeCN (250ml), resulting in a two-phase liquid system. This was heated under reflux for 16h, and then chilled to precipitate copper(i) chloride. The supernatant, consisting of a dark MeCN layer and a colourless phase of TIPSCl, was separated, and the MeCN phase was extracted with pentane. The pentane extract and the TIPSCl phase were combined, concentrated and distilled, to give the product (0.25 mol, 100%), b.p. 88-92 °C/18 mmHg. 

Two-phase liquid systems or liquid membranes have found applications in various separation technologies. Liquid membranes have an advantage over traditional... 

The excellent correlation between calculated and experimental log P values was obtained by vast investigations of the partitioning of simple chemicals in different mutually immiscible two-phase liquid systems by means of universal model based on the MOD theory [23] ... 

Ruelle, P. Universal model based on the mobile order and disorder theory for predicting lipophilidty and partition coefficients in all mutually immiscible two-phase liquid systems. Chem. Inf. Comput. Sci. 2000, 40, 681-700. 

An answer to that important challenge can now be provided, thanks to the use of a two-phases liquid system. In that system, the two different polymers are dissolved each in a good solvent of theirs, the two solvents used being immiscible. The critical point is to provide one of the two partners with a reactive end-group (i.e. x on PA in solvent A ) having a preferential compatibility with the solvent (i.e. B ) of the other partner (i.e. PB-y), and vice-versa. 

For the two-component, two-phase liquid system, the question arises as to how much of each of the pure liquid components dissolves in the other at equilibrium. Indeed, some pairs of liquids are so soluble in each other that they become completely miscible with each other when mixed at any proportions. Such pairs, for example, are water and 1-propanol or benzene and carbon tetrachloride. Other pairs of liquids are practically insoluble in each other, as, for example, water and carbon tetrachloride. Finally, there are pairs of liquids that are completely miscible at certain temperatures, but not at others. For example, water and triethylamine are miscible below 18°C, but not above. Such pairs of liquids are said to have a critical solution temperature, For some pairs of liquids, there is a lower (LOST), as in the water-tiiethylamine pair, but the more common behavior is for pairs of liquids to have an upper (UCST), (Fig. 2.2) and some may even have a closed mutual solubility loop [3]. Such instances are rare in solvent extraction practice, but have been exploited in some systems, where separations have been affected by changes in the temperature. 

Ruiz-Angel, M.J., Pino, V., Carda-Broch, S., Berthod, A., Solvent systems for CCC An aqueous two phase liquid system based on a room temperature ionic liquid, /. Chromatogr., A, 1151, 65-73, 2007. 

Another approach is to separate the products from the homogeneous catalyst using a two phase liquid system. For example, this method is used in the oligomerization step of the Shell Higher Olefins Process for the manufacture of linear a-olefins.5,9-11,330 A polar nickel catalyst containing a P- chelate ligand is dissolved in a polar solvent e.g. 1,4-butanediol, which is immiscible with higher oc-olefins, and recovery of the catalyst is easily achieved by simple phase separation. 

The catalytic hydration of olefins can also be performed in a three-phase system solid catalyst, liquid water (with the alcohol formed dissolved in it) and gaseous olefin [258,279,280]. The olefin conversion is raised, in comparison with the vapour phase processes, by the increase in solubility of the product alcohol in the excess of water [258]. For these systems with liquid and vapour phases simultaneously present, the equilibrium composition of both phases can be estimated together with vapour-liquid equilibrium data [281]. For the three-phase systems, ion exchangers, especially, have proved to be very efficient catalysts [260,280]. With higher olefins (2-methylpropene), the reaction was also performed in a two-phase liquid system with an ion exchanger as catalyst [282]. It is evident that the kinetic characteristics differ according to the arrangement (phase conditions), i.e. whether the vapour system, liquid vapour system or two-phase liquid system is used. However, most kinetic and mechanistic studies of olefin hydration were carried out in vapour phase systems. 

With ion exchangers as catalysts for olefin hydration, special attention was paid to transport problems within the resin particles and to their effects on the reaction kinetics. In all cases, the rate was found to be of the first order with respect to the olefin. The role of water is more complicated but it is supposed that it is absorbed by the resin maintaining it in a swollen state the olefin must diffuse through the water or gel phase to a catalytic site where it may react. The quantitative interpretation depends on whether the reaction is carried out in a vapour system, liquid-vapour system or two-phase liquid system. In the vapour system [284, 285], the amount of water sorbed by the resin depends on the H20 partial pressure it was found at 125—170°C and 1.1—5.1 bar that 2-methyl-propene hydration rate is directly proportional to the amount of sorbed water... 

Complexation of inorganic cations such as alkaline or alkaline earth metals by macrocyclic polyethers produces large, lipophilic cationic metal-macrocycle complexes that are readily soluble in nonpolar solvents such as benzene, toluene and haloalkanes. In order to maintain charge balance, the cationic complex has an associated counter anion. In an immiscible two-phase liquid system, such as a mixture of chloroform and water, the anion is necessarily pulled into the organic phase as the cationic complex crosses the phase boundary. A simple illustration of this principle is obtained by addition of a chloroform solution of [18]crown-6 to an aqueous solution of potassium picrate (potassium 2,4,6-trinitrophenolate). The yellow colour of the picrate anion is transported rapidly into the contiguous (physically in contact) chloroform phase upon agitation (Figure 3.43). 

Ozone is commonly prepared by silent electric discharge in oxygen, which gives up to 10% 03. The gas is blue. Pure ozone can be obtained by fractional liquefaction of 02—03 mixtures. There is a two-phase liquid system the one with 25% of 03 is stable, but a deep purple phase with 70% of 03 is explosive, as is the deep blue pure liquid (bp -112°C). The solid (mp -193°C) is black violet. Small quantities of 03 are formed in electrolysis of dilute sulfuric acid, in some chemical reactions producing 02, and by the action of uv light on 02 the combination of certain peroxo radicals and some chemical reactions may also result in 03.19... 

On mixing solutions of a protein and a polysaccharide, four kinds of mixed solutions can be obtained. Figure 3.1 shows that two single-phase systems (1 and 3) and two-types of biphase systems (2 and 4) can be produced. The two-phase liquid systems 2 and 4 differ in the distribution of biopolymers between the co-existing phases. The biopolymers are concentrated either in the concentrated phase of system 2 because of interbiopolymer complexing, or within separated phases of system 4 because of incompatibility of the biopolymers. The term biopolymer compatibility implies miscibility of different biopolymers on a molecular level. The terms incompatibility or limited thermodynamic compatibility cover both limited miscibility or limited cosolubility of biopolymers (i.e., system 2) and demixing or phase separation... 

The solvated ion pair [(C8Hi7)3NMe] [RhCl4]", formed from aqueous rhodium trichloride and Aliquat-336 in a two-phase liquid system, hydrogenates a,p-unsaturated ketones and esters selectively at the C==C double bond. The reduction of benzylideneacetone follows first-order kinetics in substrate below 0.2 M, and approaches second-order in hydrogen at partial pressures below 0.12 atm (1 atm = 101.3 kPa). The catalysis also depends on the nature of the solvent, the phase transfer catalyst and stirring rates. 

Countercurrent chromatography has been mainly developed and used for preparative and analytical separations of organic and bio-organic substances [1], The studies of the last several years have shown that the technique can be apphed to analytical and radiochemical separation, preconcentration, and purification of inorganic substances in solutions on a laboratory scale by the use of various two-phase liquid systems [2], Success in CCC separation depends on choosing a two-phase solvent system that provides the proper partition coefficient values for the compounds to be separated and satisfactory retention of the stationary phase. The number of potentially suitable CCC solvent systems can be so great that it may be difficult to select the most proper one. 

The method used is tensiometric ( ) and depends on the fact that a fibre immersed in a two phase liquid system results in the formation of a meniscus, leading to an apparent increase in the weight of the fibre (Figure 2). 

Grilc V, Minimum impeller speed for dispersion of two phase liquid systems,... 

More than a century ago, Pickering [2] and Ramsden [3] investigated paraffin-water emulsions contains solid particles such as iron oxide, silicon dioxide, barium sulfate, and kaolin and discovered that these micron-sized colloids generate a resistant film at the interface between the two immiscible phases, inhibiting the coalescence of the emulsion drops. These so-called Pickering emulsions are formed by the self-assembly of colloidal particles at fluid-fluid interfaces in two-phase liquid systems (Fig. 1). 

Azran, J., 0. Buchman, I. Amer, and J. Blum, Selective Hydrogenation of a, 8-Unsaturated Carbonyl Compounds by Rhodium Trichloride and Aliquat 336 in a Two-Phase Liquid System,7. MoL CataL, 34, 229 (1986). 

Finally, we note that the equilibrium pressure above a two-phase liquid system, as indicated in Illustration 11.3-1, is computed from... 

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