Purify organic solvent

Similar but even more pronounced anionic effects were observed with liquid membranes based on ionophore 80 and exhaustively purified organic solvents (nitrobenzene or 1,2-dichloroethane) but no polymer matrix. The use of such membranes allows to minimize the concentration of ionic impurities that could take the role of anionic sites. For a membrane with ionophore 80, the SHG response... 

This procedure allows the differentiation of odor active compounds from odorless substances within a complex mixture of volatiles. For decades this procedure has been successfully applied for aroma analyses of foods (Grosch, 1993). The mixture of volatile compounds either collected in a purified organic solvent extract or in a defined headspace volume is separated into its different components by means of GC and the effluent gas flow at the end of the GC capillary column is split between a FID and an experienced test person s nose. By sniffing the column effluent, the human nose is able to perceive the odor active compounds contained in a complex mixture and the test person can mark the corresponding spot in the FID chromatogram recorded in parallel and attribute a certain odor quality. A sample GC—O chromatogram of a solvent extracted material is shown in Figure 8.7. 

After separation, the organic solvent phase is distilled to recover the phenols and purified organic solvent for recycle. 

Purification of Laboratory Chemicals, 5th ed., Armarego, W. L. F. et al. Butter-worth- Heinemann, Amsterdam, 2003. Brief procedures for purifying organic solvents and reagents in the laboratory. 

In the commercial extraction of alkaloids from the drugs in which they exist, the powdered drug, or an alcoholic extract of it, is treated with an alkali such as ammonia or lime to liberate the alkaloid and the alkaloid is then extracted by means of an organic solvent. The crude material thus obtained is purified and finally crystallized either as the base itself or as its water-soluble salts. 

Research has shown that ascorbic acid can be produced from hulls of immature walnuts by extracting the hull with 0.2% sulfur dioxide solutions, and purifyiag the extract by adsorption on and elution from anion-exchange resias (see Ion exchange). Eluates from the anion-exchange step are concentrated, purified by organic solvent fractionations, decolorized, and crystallized (35). 

Latexes of synthetic resins are identified by ir spectrometry. Selective extraction with organic solvents is used to obtain purified fractions of the polymers for spectrometric identification. Polymeric films can be identified by the multiple internal reflectance ir technique, if the film is smooth enough to permit intimate contact with the reflectance plate. TAPPI and ASTM procedures have not been written for these instmmental methods, because the interpretation of spectra is not amenable to standardization. 

Polyethers prepared from propylene oxide are soluble in most organic solvents. The products with the highest hydroxyl number (lowest molecular weight) are soluble in water, not in nonpolar solvents such as hexane. The solubihty of 3000 molecular weight triols is high enough in solvents such as toluene, hexane, and methylene chloride that the triols can be purified by a solvent extraction process. 

The extraction of metal ions depends on the chelating ability of 8-hydroxyquinoline. Modification of the stmcture can improve its properties, eg, higher solubility in organic solvents (91). The extraction of nickel, cobalt, copper, and zinc from acid sulfates has been accompHshed using 8-hydroxyquinohne in an immiscible solvent (92). In the presence of oximes, halo-substituted 8-hydroxyquinolines have been used to recover copper and zinc from aqueous solutions (93). Dilute solutions of heavy metals such as mercury, ca dmium, copper, lead, and zinc can be purified using quinoline-8-carboxyhc acid adsorbed on various substrates (94). 

Unlike HEC and CMC, which are purified by washing with aqueous organic solvents, methylceUulose and its hydroxyalkyl modifications are purified in hot water where they are insoluble. As with other cellulose ethers, drying and grinding complete the process. 

Purification is carried out by recrysta11i2ation from organic solvent (6) or from sulfuric acid (7). Highly purified product is manufactured by continuous vacuum distillation (8). 

No attempt should be made to purify perchlorates, except for ammonium, alkali metal and alkaline earth salts which, in water or aqueous alcoholic solutions are insensitive to heat or shock. Note that perchlorates react relatively slowly in aqueous organic solvents, but as the water is removed there is an increased possibility of an explosion. Perchlorates, often used in non-aqueous solvents, are explosive in the presence of even small amounts of organic compounds when heated. Hence stringent care should be taken when purifying perchlorates, and direct flame and infrared lamps should be avoided. Tetra-alkylammonium perchlorates should be dried below 50° under vacuum (and protection). Only very small amounts of such materials should be prepared, and stored, at any one time. 

Amides are stable compounds. The lower-melting members (such as acetamide) can be readily purified by fractional distillation. Most amides are solids which have low solubilities in water. They can be recrystallised from large quantities of water, ethanol, ethanol/ether, aqueous ethanol, chloroform/toluene, chloroform or acetic acid. The likely impurities are the parent acids or the alkyl esters from which they have been made. The former can be removed by thorough washing with aqueous ammonia followed by recrystallisation, whereas elimination of the latter is by trituration or recrystallisation from an organic solvent. Amides can be freed from solvent or water by drying below their melting points. These purifications can also be used for sulfonamides and acid hydrazides. 

Water-soluble salts are best purified by preparing a concentrated aqueous solution to which, after decolorising with charcoal and filtering, ethanol or acetone is added so that the salts crystallise. They are collected, washed with aqueous ethanol or aqueous acetone, and dried. In some cases, water-soluble salts can be recrystallised satisfactorily from alcohols. Water-insoluble salts are purified by Soxhlet extraction, first with organic solvents and then with water, to remove soluble contaminants. The purified salt is recovered from the thimble. 

Bromofuran [22037-28-1 ] M 147.0, b 38.5 /40min, 50 /110min, 102.5-103 /atm, d 1.661, n 1.4970. Purified by two steam distillations and dried over fresh CaO. It can be dried over Na metal (no obvious reaction) and fractionated. It is not very soluble in H2O but soluble in organic solvents. Freshly distilled, it is a clear oil, but darkens on standing and eventually resinifies. It can be stored for long periods by covering the oil with an alkaline soln of hydroquinone and redistilled when required. It forms a characteristic... 

Up 1.4575. Purified by dilution with an equal volume of pet ether, then saturated with dry HBr. The ppte was filtered off, washed with small vols of pet ether, then cineole was regenerated by stirring the crystals with H2O. It can also be purified via its o-cresol or resorcinol addition compds. Stored over Na until required. Purified by fractional distn. Insoluble in H2O but soluble in organic solvents. [IR Kome et al. Nippon Kagaku Zasshi [J Chem Soc Japan (Pure Chem Sect)] 80 66 1959 Chem Abstr 603 1961.]... 

H2O). Purified by distn in vacuo. It is a slightly hygroscopic viscous oil. Soluble in H2O and organic solvent. It is hydrolysed by alkali and strong acid. [Rabin J Am Pharm Assoc (Sci Ed) 37 502 794[Pg.555]

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