Extraction with organic solvents

EXTRACT ORGANIC SOLVENT WITH HEPTANE (NONSOLVENT) TO HARDEN MICROSPHERES... 

For vanadium solvent extraction, Hon powder can be added to reduce pentavalent vanadium to quadrivalent and trivalent Hon to divalent at a redox potential of —150 mV. The pH is adjusted to 2 by addition of NH, and an oxyvanadium cation is extracted in four countercurrent stages of mixer—settlers by a diesel oil solution of EHPA. Vanadium is stripped from the organic solvent with a 15 wt % sulfuric acid solution in four countercurrent stages. Addition of NH, steam, and sodium chlorate to the strip Hquor results in the precipitation of vanadium oxides, which are filtered, dried, fused, and flaked (22). Vanadium can also be extracted from oxidized uranium raffinate by solvent extraction with a tertiary amine, and ammonium metavanadate is produced from the soda-ash strip Hquor. Fused and flaked pentoxide is made from the ammonium metavanadate (23). 

Metal impurities can be determined qualitatively and quantitatively by atomic absorption spectroscopy and the required purification procedures can be formulated. Metal impurities in organic compounds are usually in the form of ionic salts or complexes with organic compounds and very rarely in the form of free metal. If they are present in the latter form then they can be removed by crystallising the organic compound (whereby the insoluble metal can be removed by filtration), or by distillation in which case the metal remains behind with the residue in the distilling flask. If the impurities are in the ionic or complex forms, then extraction of the organic compound in a suitable organic solvent with aqueous acidic or alkaline solutions will reduce their concentration to acceptable levels. 

Diaziridines are weak bases, They can be extracted from organic solvents with aqueous mineral acids. With increasing number and chain length of alkyl substituents the solubility in aqueous mineral acids decreases. l-MethyI-2-n-butyl-3-hexyldiaziridine is soluble only in concentrated hydrochloric acid. Stable oxalates can in some cases be prepared from 1-aIkyI-diaziridines (43). The salts are stable indefinitely and by the action of alkali the diaziridines can be recovered. Diaziridines dialkylated on nitrogen (44) are hardly capable of salt... 

This section provides a brief review of a number of chelating and other extraction reagents, as well as some organic solvents, with special interest as to their selective extraction properties. The handbook of Cheng et al. should be consulted for a more detailed account of organic analytical reagents.11... 

A solution of 10-(piperazin-l-yl)-10,ll-dihydrodibenzo[6,/]thiepin (2.5 g, 8.4 mmol) in 100% formic acid (20 mL) was refluxed at 150 C for 6 h. The excess acid was removed by distillation at reduced pressure and the residue was treated with 10% aq NH3 (20mL), extracted with benzene (50mL) and the benzene solution was washed with dil HC1 and evaporated to dryness to give a neutral residue yield 1.8 g (98 %) mp 88 C (EtOH) (Note benzene should be replaced by organic solvents with lower toxicity). 

The cyanohydrin product was extracted into organic solvent with the addition of saturated ammonium sulfate (2.5 mL) and ethyl acetate (25 mL) while continuing to stir. The organic layer was transferred to another vessel and evaporated under nitrogen, yielding an oil (Table 1). 

Why is the extraction of a metal ion into an organic solvent with 8-hydroxyquinoline more complete at higher pH ... 

The decanted chloroform solution from the preceding preparation is evaporated and the residual oil distilled in steam. The residue is repeatedly extracted with petroleum (B.pt. 80° to 100° C.) and from the extracts small, pale yellow needles, M.pt. 98° to 99° C., are finally isolated. The product is insoluble in water, but dissolves in aqueous sodium hydroxide or the usual organic solvents with concentrated sulphuric acid it gives a green coloration. Boiling with concentrated hydriodic acid eliminates the selenium with the production of 5-iodo-o-cresol. 

Determinative and confirmatory methods of analysis for PIR residue in bovine milk and liver have been developed, based on HPLC-TS-MS (209). Milk sample preparation consisted of precipitating the milk proteins with acidified MeCN followed by partitioning with a mixture of -butylchloride and hexane, LLE of PIR from aqueous phase into methylene chloride, and SPE cleanup. The dry residue after methylene chloride extraction was dissolved in ammonium hydroxide, and this basic solution was transferred to the top of Cl8 SPE column. The PIR elution was accomplished with TEA in MeOH. For liver, the samples were extracted with trifluoroacetic acid (TFA) in MeCN. The aqueous component was released from the organic solvent with n-butyl chloride. The aqueous solution was reduced in volume by evaporation, basified with ammonium hydroxide, and then extracted with methylene chloride. The organic solvent was evaporated to dryness, and the residue was dissolved in ammonium acetate. The overall recovery of PIR in milk was 94.5%, RSD of 8.7%, for liver 97.6%, RSD of 5.1 %. A chromatographically resolved stereoisomer of PIR with TS-MS response characteristics identical to PIR was used as an internal standard for the quantitative analysis of the ratio of peak areas of PIR and internal standard in the pro-tonated molecular-ion chromatogram at m/z 411.2. The mass spectrometer was set for an 8 min SIM-MS acquisition. Six samples can be processed and analyzed in approximately 3 hours. 

Non-polymerisable monofunctional antioxidants were subsequently used to avoid the problem of homopolymerisation of the antioxidant. For example, melt grafting of the two maleated antioxidants, BPM and APM, on PP was shown to lead to high grafting efficiencies (up to 75% in the former and >90% in the latter) which were attributed to the non-polymerisable nature of the maleate (maleimide) functions [57, 59, 60]. The performance of these antioxidants, especially under extractive organic solvent conditions, was also shown to far exceed that of conventional antioxidants with similar antioxidant functions. Table 2, for example, shows the advantages of the grafted... 

Wood also contains extractives—organics removable with inert solvents—and the extracts vary with the species and the location in the tree. 

The methods employed for isolation of the alkaloids depend on the nature of the compounds, and specific conditions have frequently been devised for the selective isolation of particular types of compounds. Usually, fresh or dried plant material is extracted with dilute acid solution or with alcohol, and the extract obtained is further fractionated by extraction into organic solvents with variation of pH. Extraction columns (288), membrane processes (425), and ion-exchange materials (288-290) may be particularly useful for subfractionation or isolation procedures. For further identification and isolation of separate compounds, preparative thin-layer chromatography, (288, 291, 292, 426), liquid chromatography (293, 294), or gas chromatography may be used (202, 296, 297). Because some of the products reviewed in this chapter occur naturally in very small amounts, they have not been isolated in crystalline form. Gas chromatography-mass spectrometry (87, 213, 299), mass fragmentography (192), and mass spectrometry-mass spectrometry (301, 359) have proved to be particularly useful techniques for identification of trace alkaloids in complex mixtures. 

The recovery and purification of furfural from aqueous effluents by high-pressure extraction is of technical interest. Alternative extraction tests with supercritical carbon dioxide were carried out [1,2]. Further research [3-5] led to the conclusion that carbon dioxide is a good alternative to organic solvents with comparable and even better extraction results. For all these experiments the system furfural - water without acetic acid was used. 

---