Extraction three-phase liquid

The first demonstration of fluorous synthesis was in the preparation of small (8-12 members) isoxazo-line and isoxazole libraries by the three-step procedure outlined in Figure 8.1461 All reactions were purified by three-phase liquid-liquid extraction. The starting substrates were simple allylic alcohols which were tagged with the fluorous silyl halide 5 to make substrates 6 for an ensuing dipolar cycloaddition. This was conducted by the Mukaiyama method with a large excess of nitro compound and... 

A three-phase liquid-liquid partitioning consisting of hexane, acetonitrile, and dichloromethane has also proven to be a preferred cleanup method for diethylstilbestrol and zeranol (455), trenbolone and epitrenbolone (445), trenbolone and nortestosterone (446), and melengestrol residues (456) in tissues. Following adjustment of the initial aqueous acetonitrile sample extract at pH 13, most of the polar and ionic acidic matrix components were directed into the aqueous layer during the partitioning process, while the low-polarity components were extracted... 

In addition, residues of corticosteroids can be cleaned up through application of a three-phase liquid-liquid partition system consisting of acetonitrile, hexane, and dichloromethane. Since its inception, this procedure has been used successfully to perform a fast, crude fractionation of tissue components and drugs extracted from tissue homogenates into the aqueous acetonitrile supernatant. Non-... 

Kenig, E.Y., Kholpanov, L.P., Malyusov, V.A. Calculation of three-phase liquid extraction parameters in multicomponent mixtures. Proc. Acad. Sci. USSR, Chem. Technol. Section 313, 83-86, 1990. 

In another type of membrane extraction devices, porous polypropylene hollow fibers are used, often in a disposable way, which minimizes carryover problems and reduces costs [26-33]. On the other hand, manual manipulations are needed, limiting the possibility for automation. With these devices, the extraction can be carried out in a static mode, either in large sample volumes, where the extraction is not intended to be complete, or in small volumes aiming for complete extraction. Usually, stirring is applied to increase the speed of mass transfer. Some typical practical arrangements are shown in Figure 12.2. This type of SLM extraction is often called hollow fiber liquid phase microextraction, or three-phase liquid phase microextraction or two-phase liquid phase microextraction but the terminology in this active field of research has not been settled. Also hollow fibers can be connected in flow systems [34,35]. 

Three-phase liquid membrane Supported liquid membrane extraction SLM [6,85]... 

Note SLM, supported liquid membrane (aq/org/aq) MMLLE, microporous membrane liquid-liquid extraction (aq/org) PME, polymer membrane extraction (aq/polymer/org) MESI, membrane extraction with sorbent interface (aq (or gas)/polymer/gas/sorbent) CFLME, continuous flow liquid membrane extraction (aq/org (in flow)/aq) LPME2, two-phase liquid phase microextraction in hoUow fibers (aq/org) LPME3, three-phase liquid phase microextraction in hollow fibers (aq/org/aq). 

Three-phase liquid membrane extraction Supported Uquid membrane extraction SLM 16,98]... 

The cooled mixture is transferred to a 3-1. separatory funnel, and the ethylene dichloride layer is removed. The aqueous phase is extracted three times with a total of about 500 ml. of ether. The ether and ethylene chloride solutions are combined and washed with three 100-ml. portions of saturated aqueous sodium carbonate solution, which is added cautiously at first to avoid too rapid evolution of carbon dioxide. The non-aqueous solution is then dried over anhydrous sodium carbonate, the solvents are distilled, and the remaining liquid is transferred to a Claisen flask and distilled from an oil bath under reduced pressure (Note 5). The aldehyde boils at 78° at 2 mm. there is very little fore-run and very little residue. The yield of crude 2-pyrrolealdehyde is 85-90 g. (89-95%), as an almost water-white liquid which soon crystallizes. A sample dried on a clay plate melts at 35 0°. The crude product is purified by dissolving in boiling petroleum ether (b.p. 40-60°), in the ratio of 1 g. of crude 2-pyrrolealdehyde to 25 ml. of solvent, and cooling the solution slowly to room temperature, followed by refrigeration for a few hours. The pure aldehyde is obtained from the crude in approximately 85% recovery. The over-all yield from pyrrole is 78-79% of pure 2-pyrrolealdehyde, m.p. 44 5°. 

In the past decade, several novel solvent-based microextraction techniques have been developed and applied to environmental and biological analysis. Notable approaches are single-drop microextraction,147 small volume extraction in levitated drops,148 flow injection extraction,149 150 and microporous membrane- or supported liquid membrane-based two- or three-phase microextraction.125 151-153 The two- and three-phase microextraction techniques utilizing supported liquid membranes deposited in the pores of hollow fiber membranes are the most explored for analytes of wide ranging polarities in biomatrices. This discussion will be limited to these protocols. 

The principle of a three-phase membrane extraction is illustrated in Figure 1.28. An organic solvent is immobilized in the pores of a porous polymeric support consisting of a flat filter disc or a hollow fiber-shaped material. This supported liquid membrane (SLM) is formed by treating the support material with an organic solvent that diffuses into its pores. The SLM separates an aqueous... 

The most common (off-line) sample preparation procedures after protein precipitation are solid phase extraction and liquid-liquid extraction. Multiple vendors and available chemistries utilize 96-well plates for solid phase extraction systems and liquid-liquid extraction procedures. Both extraction process can prepare samples for HPLC/MS/MS assay. Jemal et al.110 compared liquid-liquid extraction in a 96-well plate to semi-automated solid phase extraction in a 96-well plate for a carboxylic acid containing analyte in a human plasma matrix and reported that both clean-up procedures worked well. Yang et al.111 112 described two validated methods for compounds in plasma using semi-automated 96-well plate solid phase extraction procedures. Zimmer et al.113 compared solid phase extraction and liquid-liquid extraction to a turbulent flow chromatography clean-up for two test compounds in plasma all three clean-up approaches led to HPLC/MS/MS assays that met GLP requirements. 

Numerous studies have been made of the hydrodynamics and other aspects of the behavior of gas-liquid-solid systems, in particular of trickle beds, and including absorption and extraction in packed beds. A selection of correlations of these parameters is presented in problem P8.03.02. They tell something of what is going on in three-phase reactors. 

The formulation of the three phases must be such that the liquid membrane extracts the solute from one of the phases and the third phase strips it from the membrane. Thus extraction and stripping take place in the same contactor, and the stripping phase is where the solute is accumulated, instead of the organic phase as in the case of conventional solvent extraction. This allows for a middle phase of small volume that, being thin, behaves like a membrane. 

An oven-dried 100 ml flask with a side arm dosed with a septum is fitted with a magnetic stirring bar and a reflux condenser connected to a mercury bubbler. The flask is cooled to room temperature under nitrogen, charged with 4.36 g (0.025 mol) of adipic acid monoethyl ester followed by 12.5 ml of anhydrous tetrahydrofuran, and cooled to —18° by immersion in an ice-salt bath. Then 10.5 ml of 2.39 m (or 25 ml of 1 m) solution of borane in tetrahydrofuran (0.025 mol) is slowly added dropwise over a period of 19 minutes. The resulting clear reaction mixture is stirred well and the ice-salt bath is allowed to warm slowly to room temperature over a 16-hour period. The mixture is hydrolyzed with 15 ml of water at 0°. The aqueous phase is treated with 6 g of potassium carbonate (to decrease the solubility of the alcohol-ester in water), the tetrahydrofuran layer is separated and the aqueous layer is extracted three times with a total of 150 ml of ether. The combined ether extracts are washed with 30 ml of a saturated solution of sodium chloride, dried over anhydrous magnesium sulfate, and evaporated in vacuo to give 3.5 g (88%) of a colorless liquid which on distillation yields 2.98 g (75%) of ethyl 6-hydroxyhexanoate, b.p. 79°/0.7 mm. 

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