Materials, extraction-chromatographic

Syn 3-(EthyltHloniethyl)-4-hydroxy-6-pt)enyl-2-hexanone (4) and anti (5) To ethanethiol (10 0 mg 0 17 mmol) in THF (2 mL) was added 1 54 M n butyltittnum m hexane (0 11 mL) at 0 C under Ar Stannous triflate (69 0 mg 017 nvnol) was added and alter 20 mm the mocture was cooled to 4S°C Methyl vinyl Ketone 1 (118 mg 1 98 mmol) m THF (1 5 mL) was added followed by 3 phenyiptopanal 3 350 mg 2 61 mmol) m THF (1 S mL) Alter 12 h aq cilnc acid was added and the organic material extracted with OHjClj The resxlue after evaporation was dissolved in MeOH and treated with citric acxt After 30 min stimng, the mixture was quenched with pH 7 phosphate buffer extracted with CH2CI2, the solvent evaporated and the residue chromatographed to afford 336 mg ot 4 (75%), syn anti (90 10)... 

The common methods of purification, discussed below, comprise distillation (including fractional distillation, distillation under reduced pressure, sublimation and steam distillation), crystallisation, extraction, chromatographic and other methods. In some cases, volatile and other impurities can be removed simply by heating. Impurities can also sometimes be eliminated by tbe formation of derivatives from which the purified material is regenerated (see Chapter 2). 

A mixture of 9.05 g (0.05 mol) of bcnzaldchydc anilide and 7.87 g (0.07 mol) of potassium /-butoxidc in 200 mL of DMb is cooled to —40 C under N2. This mixture is stirred and maintained at this temperature while a solution of 10.47 g (0.07 mol) of 2-chloro-Ar,/V-diethylacetamide in 125 mL of l)MF. is added over a 2-hr period. The reaction is allowed to warm to r.t. over a 30-min period and concentrated to a small volume in vacuo at 35 C. The residue is diluted with H20 and Et,0. After removal of the Ei20 layer, the aqueous fraction is extracted with another two portions of Er2(), and the combined extracts are dried over MgS04. Filtration and evaporation gives 16.32 g of crude material. This material is chromatographed on deactivated alumina with initial elution with pet. ether followed by benzene. Two pure fractions are obtained which, after reciystalli/.aiiou from ben/ene/pet. ether, are identified as the (ranj-isomer 3a yield 1.03 g (7%) mp 90-92eC. and the cts-isomer 3b yield 8.53 g (58%) mp 80.5-82.5cC. 

Today SCFs are used for natural product extractions, chromatographic separations, pollution prevention, material processing and as solvents for chemical reactions.[75-77] Chemical applications include catalysis, polymerization, enzymatic reactions and organic synthesis. 

Oi T, Odagiri T, Nomura M (1997) Extraction of lithium from GSJ rock reference samples and determination of their lithium isotopic compositions. Anal Chim Acta 340 221-225 Oi T, Shimizu K, Tayama S, Matsuno Y, Hosoe M (1999) Cubic antimonic acid as column-packing material for chromatographic lithium isotope separation. Sep Sci Tech 34 805-816 Olsher U, Izatt RM, Bradshaw JS, Dailey NK (1991) Coordination chemistry of lithium ion a crystal and molecular structure review. Chem Rev 91 137-164... 

The extraction of two typical agricultural products from environmental matrices were chosen as examples for the operation of this system. Diuron, a phenylmethylurea, was freshly spiked onto Tama soil. This soil was characterized and shown to have 3.1% organic material and 14 % clay fraction. In addition, a phenyl metabolite of NUSTAR, a systemic fungicide, on wheat previously unextractable by SFE was extracted. The wheat sample was not classified for its chemical composition. Both samples were treated with radiolabeled compounds (E. I. du Pont de Nemours and Company, Du Pont Agricultural Products, Wilmington, DE) and extraction results are from liquid scintillation counting of the sample extract. Chromatographic evaluation of the Diuron from soil extracts has previously been published (2). 

Column-based separation approaches are well suited for the isolation of radionuclides from complex sample matrixes in a rapid automated format. The development of automated radioanalytical methods is, in fact, closely coupled to the availability of extraction chromatographic materials. In this review, we will focus on the... 

The most important solid-phase separation materials for column-based separations in modern radioanalytical chemistry are extraction chromatographic materials, and these have been particularly important in automated radioanalytical chemistry. Solid-phase extraction materials based on the covalent attachment of ligands to solid supports also exist, and they have found application in large-scale separation processes for waste or effluent treatment.22 25 They have been commercialized as Analig or SuperLig materials by IBC Advanced Technologies (American Fork, UT). However, they are less well characterized or used for small-column analytical separations. 

Extraction chromatographic materials for analytical separations have been commercialized by Eichrom Technologies, Inc. (Darien, IL). These typically use extractants and solvents known in the field of liquid/liquid extraction for radiochemical separations. Some of the extractants and solvents used are shown in Scheme 9.1. 

The prevailing extraction-chromatographic method for 90Sr separation entails the use of Sr-Resin.116"119 This material is prepared by impregnating a porous polymer with a 1-octanol solution of the crown ether 4,4 (5 )-bis(t-butylcyclohexano)-18-crown-6 (DtBuCH18C6). This material will extract and retain Sr from 2-8 M HN03 solutions, while most of the matrix constituents are not retained and are removed with a column wash. The separated Sr is released by elution with water or weak nitric acid. The extraction equilibrium is shown in Equation 9.2, where the bar above a species indicates that it is immobilized on the resin.4... 

Another multisyringe FI separation system design has been used in the analysis of stable and radioactive Y, using an extraction-chromatographic material containing HDEHP adsorbed on a C18 support.123 Separated samples were analyzed off-line by ICP-AES and proportional counting. This system used four syringe pumps in parallel. 

Actinides can be separated from matrix elements, other radionuclides, and each other using extraction-chromatographic materials such as TEVA-Resin, TRU-Resin, and UTEVA-Resin. The capacity factors for various actinides on these resins, as a function of nitric or hydrochloric acid concentrations are shown in Figures 9.11 and 9.12.30 31127 Elution peaks or collected fractions from column separations can be... 

TEVA-Resin is an extraction-chromatographic material based on Aliquat 336, which is a liquid quaternary ammonium salt, as described previously in connection with "Tc separations.30 It acts as a strongly basic anion-exchange material, retaining tetravalent actinides from 2-4 M HN03 solutions as anionic nitrato complexes (see Figure 9.11). Am(III), Np(V), and U(VI) are much less retained. The extraction... 

The development of solvent-impregnated resins and extraction-chromatographic procedures has enabled the automation of radiochemical separations for analytical radionuclide determinations. These separations provide preconcentration from simple matrices like groundwater and separation from complex matrixes such as dissolved sediments, dissolved spent fuel, or nuclear-waste materials. Most of the published work has been carried out using fluidic systems to couple column-based separations to on-line detection, but robotic methods also appear to be very promising. Many approaches to fluidic automation have been used, from individual FI and SI systems to commercial FI sample-introduction systems for atomic spectroscopies. 

Horwitz, E. P, Dietz, M. L., and Chiarizia, R., The application of novel extraction chromatographic materials to the characterization of radioactive waste solutions, J. Radioanal. Nucl. Chem., Articles, 161, 575-583, 1992. 

Dietz, M. L., Yaeger, J., Sajdak, L. R., and Jensen, M. P., Characterization of an improved extraction chromatographic material for the separation and preconcentration of strontium from acidic media, Sep. Sci. Technol., 40, 349-366, 2005. 

Collection on a sorbent involves the use of a solid material, either in the line or at the restrictor outlet. A number of materials have been [13] and continue to be investigated [14-16] with a view to optimizing collection of different types of analytes. This collection mode involves an additional step desorbing the analytes from the sorbent by elution with a small volume of solvent for their subsequent determination or, alternatively, thermal desorption and sweeping by the eluent if an on-line coupled extraction-chromatographic system is being used. 

In a typical experiment, styrene (180 mg, 1.74 mmol) was admixed with clayfen or clayan (300 mg) in a glass tube. The reaction mixture was placed in an oil bath for 15 min or irradiated for 3 min in an alumina bath inside an unmodified household microwave oven (900 W) at its medium power. On completion of the reaction, followed by TLC examination (hexane-EtOAc, 4 1, v/v), the product was extracted into dichloromethane (45 mL), the combined organic extract dried with anhydrous sodium sulfate and solvent removed under reduced pressure. The relative amounts of product distribution were calculated from GC-MS analysis. Alternatively, the crude material was chromatographed on a silica gel column and eluted with hexane-EtOAc (4 1, v/v) to afford the pure product (147 mg, 57%). 

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