Oxygen-containing solvents

Some common oxygen-containing solvents give isolatable Hg(I) complexes. For example, both diglyme and 1,4-dioxane form Hg2(solvent)2(N03)2 complexes. The diglyme complex forms when Hg2(N03)2 2 HjO is dissolved in diglyme containing a little CH(OEt)3 to remove HjO. The dioxane complex forms in MeOH. 

Oxygen-containing solvents with a strong coordinating ability, such as diethyl ether, methyl /.so-butyl ketone and /.so-amyl acetate, form oxonium cations with protons under strongly acidic conditions, e.g. (R20) H. Metals which form anionic complexes in strong acid can be extracted as ion pairs into such solvents. For example, Fe(III) is extracted from 7 M hydrochloric acid into diethyl ether as the ion pair... 

Oxygen-containing solvents such as water, alcohols or ethers are such poor donors that few complexes with palladium(II) have been isolated. The most important class of complexes of this type consists of those containing water, which are formed as intermediates in the substitution reactions of palladium(II) when carried out in aqueous solution. In these reactions their formation is in competition with the second order reaction of the complex with the incoming ligand. The aqua complexes can also be formed by reaction of halo complexes with silver salts (e.g. N03, C104, BF4) in water. These complexes are acidic, being in equilibrium with hydroxo complexes in neutral or basic media. 

It has now been found that the list of basic solvents that give such reactions includes benzophenone, phenyl acetate, cyclooctanone, and many other oxygen-containing solvents. Even benzene has been found to give such a complex (64). 

Caution solutions of LiAlFLi in oxygen-containing solvents may decompose at elevated temperatures ( 160 C). Therefore, distillation should never be carried out to dryness, and solvents boiling above 100 C shotild be distilled under reduced pressure. 

The kind of useful polymerization solvents depends on the reactivity of monomers. tert-Butylacetylene polymerizes not only in oxygen-containing solvents (1,4-dioxane, anisole, methyl benzoate, acetophenone, etc.) but also in nitrogen-containing solvents (benzonitrile, acetonitrile, nitrobenzene, nitroethane, etc.)19). Therefore, it can be said that tm-butylacetylene is one of the most reactive monomers in the polymeriza-... 

The use of a sodium-tin alloy for the preparation of tetramethyltin preceded use of the corresponding sodium-lead alloy (64,66), but was subsequently displaced by other methods. Currently, the Direct Reaction is used to prepare dialkyltin dihalides, and generally requires an oxygen-containing solvent plus another metal as accelerator (66) ... 

Solid iodine is purple, as is its vapor (I2), but iodine is often brown in solution, for example, in oxygen-containing solvents such as ethanol tincture of iodine antiseptic) or in water, in which its solubility is increased by formation of a complex ion Is" with iodide ion. Iodine is obtained by oxidizing the ash of dried seaweeds (kelp) alternatively, sodium iodate, which is present in the NaNOs deposits of the Atacama desert in Chile, may be reduced to iodide with aqueous HSO3" ion, followed by the iodide/iodate analog of reaction 12.23 if elemental iodine is wanted. Most of the U.S. production, however, comes from chlorination of natural I"-bearing brines in Michigan (cf. reaction 12.21). Since iodine is a fairly volatile solid, it can be conveniently purified by sublimation. 

Heteropoly acids [oxygen compounds of Mo(VI), W(VI), Si, P(V), As(V), Ge, and other elements] and their reduction products (molybdenum blues) are extracted into oxygen-containing solvents by a mechanism similar to that above. 

A group of elements (P, As, Si, Ge, V, W, Mo etc.) forms yellow heteropoly acids which, on being reduced, give intensely coloured blue compounds. Both the heteropoly acids and their reduced forms are used for determination of the elements. All these forms are extracted with oxygen-containing solvents. It should also be mentioned that the heteropoly acid anions form extractable ionic associates with basic dyes. 

The determination of metals by thiocyanate is carried out in aqueous or aqueous-acetone media, or after extraction with oxygen-containing solvents. The extractability of metal complexes depends on the acidity of the medium, the concentration of thiocyanate, and the organic solvent. The more acidic is the aqueous phase, and the higher the thiocyanate concentration, the more thiocyanic acid (HSCN) is also extracted by the organic phase. 

Extraction of the cadmium-iodide complex from iodide-H2S04 solutions with oxygen-containing solvents (e.g., mesityl oxide, 2-ethyl-1-butanol) is a selective recommended separation method (e.g., from zinc) [1-3]. The iodide complex of cadmium can also be extracted with high molecular weight amines in xylene [4], TBP in benzene [5], and with tetra-n-butylammonium iodide in CHCI3 [6]. 

In an acidic medium (pH-1.7) and at a temperature not higher than 10°C, chromium(VI) reacts with H2O2 ( 0.02 M) to form blue perchromic acid which can be extracted into ethyl acetate, isoamyl alcohol, or similar oxygen-containing solvents. These methods permit the separation of Cr from V, Fe, and most other metals [7j. Perchromic acid can also be extracted with solutions of tertiary amines or quaternary ammonium salts [8,9]. 

The cobalt(ll) thiocyanate complex can be extracted with oxygen-containing solvents, such as a mixture of diethyl ether with isoamyl alcohol (1+1), MIBK, or acetylacetone [23,24], The molar absorptivity, e, of the complex in the ether-isoamyl aleohol mixture is about 30% smaller than in the aqueous acetone media. 

Gold(III) is usually separated from Pt and Pd by extraction from 4-8 M hydrochloric acid [18-20] or from H2S04-KBr media [21]. Oxygen-containing solvents, such as DIPE, MIBK, mesityl oxide, or amyl acetate have been used as extractants. Iron(III), which interferes, is masked with phosphoric acid before the extraction of gold. The chloride complex of gold can also be extracted with TOPO in MIBK [20], TBP in toluene or xylene [24]. The anionic... 

The iron(III)-thiocyanate complexes can be extracted with oxygen-containing solvents such as ethers, higher alcohols, esters, and ketones. Depending on the solvent used, different species are extracted. The 1 4 Fe SCN complex is extracted with diethyl ether, while the 1 3 complex is extracted with TBP. 

Niobium and tantalum form stable fluoride complexes which are extractable with oxygen-containing solvents and can thus be separated from many metals, such as Ti, Zr, Sn, Mo, W, U, and Fe [6,7]. By suitable choice of concentrations of HF, HCl, and H2SO4, tantalum can be separated from niobium and vice versa [6]. MIBK is most often used as the solvent. Niobium and Ta can be stripped from the organic phase with a H2O2 solution. 

The chloride-, bromide-, and thiocyanate complexes of ruthenium(IIl) and osmium(IV) can be extracted from acid solutions by oxygen-containing solvents, also in the presence of TBP or amines [10,12-15]. Osmium has been separated from Ru after conversion into Osle and extraction with TO A [16]. From mixtures of thiocyanate complexes of Ru and Os, only the Os complex can be extracted into diethyl ether containing a small amount of peroxide [14]. Poljmrethane foam has also been used for separating Ru and Os as their thiocyanate complexes [17,18]. 

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