Extraction from alkaline solutions

Dimethylglyoxime. The complexes with nickel and with palladium are soluble in chloroform. The optimum pH range for extraction of the nickel complex is 4-12 in the presence of tartrate and 7-12 in the presence of citrate (solubility 35-50 fig Ni mL 1 at room temperature) if the amount of cobalt exceeds 5 mg some cobalt may be extracted from alkaline solution. Palladium(II) may be extracted out of ca lM-sulphuric acid solution. 

Ethers, Esters, and Related Derivatives of Alcohols.—Oestrogens are effectively methylated at the phenolic oxygen by extraction from alkaline solution into di-chloromethane containing iodomethane, with a tetra-n-hexylammonium salt as a phase-transfer reagent ( extractive alkylation ). Conditions are mild, and the reaction is very rapid. In combination with g.l.c. analysis of the methyl ethers, it provides a simple and convenient method for the analysis of oestrogen mixtures. H-... 

Our studies have shown that in the presence of complex-forming agents actinides and lanthanides can be extracted from alkaline solution by using of ali-quat 336 and 4( c , oC -dioctylethyl)pyrocatechol. The latter reagent is more efficient, as it provides for quantitative extraction of trivalent actinides from very alkaline media and for appreciably better separation of actinides from rare earth elements. 

Candicine, like other quaternary compounds, cannot be extracted from alkaline solution with immiscible solvents. It was isolated by precipitating the purified plant extract with concentrated Mayer s reagent and then decomposing the precipitated mercuriiodide with hydrogen sulfide, the base being recovered in the form of its slightly soluble iodide. 

Additionally, extraction from alkaline solutions and carbonate is characterized by the unusual preference (specificity) of the extraction processes for the trivalent oxidation state [in carbonate solutions the order of extraction is M(III) > M(IV) > M(V)> M(VI)]. A further benefit of operation in alkaline solutions is the greater tendency for air oxidation of trivalent metal ions to the tetravalent oxidation state (examples are Ce, Bk), thus prompting their removal. 

A considerable amount of literature is available on the determination of the alkaloidal content of belladonna, most of the methods suggested being variations of the general process of extraction from the leaf by a solvent in the presence of alkali, followed by acid extraction and finally solvent extraction from alkaline solution. The variations usually differ from the general method in the first part of the process i.e. extraction of the alkaloids from the plant) which is the most difficult operation. 

Codeine is extracted from alkaline solution by chloroform and assay of its salt and galenicals is effected by normal alkaloidal extraction technique. Codeine phosphate, Ci8H2i03N,H3P04,l H20, Mol. Wt. 424-4, is official in the5.P., but the U.S.P, salt is a hemihydrate, Mol. Wt. 406-4, and this is the more usual commercial product. It may be determined by non-aqueous titration (see p. 792). 1 ml 0-1N perchloric acid = 0-03974 g Ci8H2i03N,H3P04 or 0 02994 g C,3H2i03N. 

Like codeine and unlike morphine and diamorphine, ethylmorphine is extracted from alkaline solution by chloroform and assay of its salts and preparations is effected by normal alkaloidal extraction technique. Ethyl-morphine hydrochloride, Ci9H2303N,HCl,2H20, Mol. Wt. 385-9. 1 ml... 

Pholcodine is extracted from alkaline solution by chloroform and assay of its salts and preparations follows normal alkaloidal extraction procedure. 

Analytical Procedures. Standard methods for analysis of food-grade adipic acid are described ia the Food Chemicals Codex (see Refs, ia Table 8). Classical methods are used for assay (titration), trace metals (As, heavy metals as Pb), and total ash. Water is determined by Kad-Fisher titration of a methanol solution of the acid. Determination of color ia methanol solution (APHA, Hazen equivalent, max. 10), as well as iron and other metals, are also described elsewhere (175). Other analyses frequendy are required for resia-grade acid. For example, hydrolyzable nitrogen (NH, amides, nitriles, etc) is determined by distillation of ammonia from an alkaline solution. Reducible nitrogen (nitrates and nitroorganics) may then be determined by adding DeVarda s alloy and continuing the distillation. Hydrocarbon oil contaminants may be determined by ir analysis of halocarbon extracts of alkaline solutions of the acid. 

Mooiman, M. B. Miller, J. D. The chemistry of gold solvent extraction from alkaline cyanide solution by solvating extractants. Hydrometallurgy 1991, 27, 29-46. 

As already mentioned in section 2.1 pertechnetate may be efficiently extracted by pyridine from alkaline solutions Since pyridine derivates are less soluble in the aqueous phase than pyridine, they extract technetium more efficiently even from nitrate solutions. For example, the distribution coefficients of technetium in the extraction from a 2 M (NH )2COj solution with a high nitrate concentration by pyridine and 2-methylpyridine are 7.5 and 242, respectively . Higher distribution coefficients can be achieved by using 3-methyl- or 4-methyl-pyridines. The pyridine derivates are the most promising reagents for the extraction of technetium from nitrate solutions. 

Tetraphenylborate (TPB) was used at Savannah River to recover cesium from alkaline solutions, but attempts to treat HLW tanks with TPB resulted in the production of benzene (a TPB decomposition product) at levels that did not permit the safe operation of the process.8 Crown ethers and dicarbollides were proposed as extractants to remove cesium from acidic HAW, but these compounds are not selective enough to allow cesium to be removed from solutions containing large amounts of nitric acid or sodium nitrate.9 Dicarbollides were used in Russia at industrial scale to recover cesium from HAW, but the removal of cesium was only possible after partial denitration of the liquid waste.10... 

This general phenomenon was observed when extracting cesium from neutral sodium nitrate as well as from alkaline solutions. In 1,2-DCE, however, the increase in DCs is less pronounced (possibly due to 1,2-DCE s higher polarity, which affords moderate DCs at low modifier concentrations). Nevertheless, both DCs and lij increase as a function of the concentration of the alcohol modifier 1, as shown in Table 4.18. 

Hemicelluloses have traditionally been defined by extraction procedures, i. e., hemicelluloses are those polysaccharides extracted by alkaline solutions from plant tissues after removal of low-molecular-weight substances with hot aqueous alcohol, removal of waxes and other lipid-soluble substances, delignification, and removal of pectin with an aqueous solution of a calcium ion chelator. The most abundant hemicelluloses in the primary cell walls of dicotyledons are xyloglucans. Xyloglucans have a backbone chain whose chemical stmcture is identical to that of cellulose. About 75% of the 8-D-glucopyranosyl units in that chain are substituted... 

Solvent Extraction of Transplutonium Elements from Acid Solutions by Polydentate Neutral Organophosphorus Compounds and from Alkaline Solutions by Quarternary Ammonium Bases and by Alkylpyrocatechols... 

The purpose of the present work consists in the investigation of polydentate neutral organophosphorus compounds as extractants for isolation and concentration of TPE from acid solutions and quaternary ammonium bases and alkylpyrocatechols for isolation and separation of TPE and rare earth elements from alkaline solutions. 

Extraction of transplutonium elements from alkaline solutions... 

Figure 6. Extraction of actinides and lanthanides from alkaline solutions by 0.2M aliquot 336 OH in the presence of 2.5 X 10 2M tartaric acid.

The extraction of bismuth diethyldithiocarbamate into CCI4 or CHCI3, from alkaline solution containing tartrate, cyanide, and EDTA, is a specific method for separation of Bi. After the extraction Bi can be determined either directly as the coloured complex Bi(DDTC)3 (see below), or by other methods [1,2]. 

In the determination of cadmium with dithizone it is possible to avoid the preliminary extraction from the acidic medium. Instead, one can apply a double extraction of cadmium from alkaline solutions containing cyanide first, from a solution containing 6-7% NaOH and 0.2% KCN, and secondly from a solution containing 6-7% NaOH and 0.01% KCN. Tartaric acid is used as stripping agent after the first extraction. A high concentration of cyanide prevents extraction of cadmium, whereas a relatively low one does not, provided sufficient dithizone is used. Such conditions allow separation of the cadmium from all but traces of Pb and Zn in the first extraction, and the stripping separates cadmium from Ag and... 

Diethyl dithiocarbamate extracts lead from slightly acidic media, from neutral media containing citrate, and from alkaline media containing cyanide and tartrate. When extracting from acid solutions the use of dibenzyl dithiocarbamate is advisable [2]. 

If Zn is extracted with TOA in benzene, PAN can be added directly to the extract [43]. In another method [25], the solution of PAN in ethanol is added to the chloroform extract of Zn combined with hydroxamic acid and stearylamine (e = 5.8-10 at 550 nm). More often, Zn is stripped from the extract with alkaline solution, then PAN is added, and the complex is extracted with chloroform (see procedure). The colour of the chloroform extract is stable. 

The distribution coefficients for the extraction of Zn with TOA in benzene from HCl medium, and for the extraction of the zinc-PAN chelate with chloroform from alkaline solution (pH 10-11) are so high that a single extraction is usually sufficient. 

Methyl 1-naphthyl ether (1-methoxynaphthalene) [2216-69-5] M 158.2, b 90-91°/2mm, d4 1.095, n 1.6210. Steam distil the ether from alkaline solution. The distillate is extracted with Et20. After drying (MgS04) the extract and evaporating Et20, the methyl naphthyl ether is then fractionated under reduced pressure from CaH2. The picrate has m 129.5-130.5° (from EtOH). [Beilstein 6IV 4211.]... 

Gas diffusion is slower in wet and flooded soils, where soil pores are plugged by water. Gas diffusion in water is about 1/10 000th the rate of gas diffusion in air, or essentially nil in flooded soils where all soil pores are water-filled. The consumption of 1 mole of O2 during respiration yields approximately 1 mole CO2. In flooded soils, therefore, CO2 can almost completely replace O2 and reach a partial pressure of 0.2, equal to the value of O2 in atmospheric ah. Since the gas volume in a flooded soil is minute, it is perhaps more instructive to say that the CO2 concentration in the soil solution is equivalent to Pqo2 = 0.2. At such concentrations, dissolved CO2 has considerable influence on soil pH (Eq. 7.18). When soil solutions are extracted from soils, dissolved CO2 is slowly lost to the atmosphere. This causes large pH increases in extracts from alkaline and flooded soils, and the possible precipitation of CaCC>3 and of transition and heavy metal hydroxyoxides. The loss requires several hours so immediate measurements yield pH values more representative of actual soil conditions. 

Nickel is extracted from alkaline ammonia solutions by LIX 64N, but its equilibrium constant is five orders of magnitude smaller than that of copper.8 Also, it forms ammonia complexes more extensively than copper, which enhances the selectivity of LIX 64N for copper over nickel. Under conditions of simultaneous extraction the parameters of the chemical-reaction model for each individual metal are able to predict the iwo-metal equilibria provided that the equilibrium distribution of species in the aqueous phase is taken into account. 

---