Salts, hydrated, isolation

Hammett equation, applied to azines, 217 Hetarynes, 121-143 contrasted with arynes, 125 Heteroaromatic compounds, covalent hydration of, 1-41 "pKa generalizations for, 48-61 Heterocyclic acids, pH-rate profile for, 67 Heterocyclic diazonium compounds, 241 Heptaazanaphthalenes, 393 Hexaazanaphthalenes, 393 Hippuroflavin, 80 Hydrated salts, isolation of, 16 Hydrates, alcoholates from, 16 isolation of, 16... 

Ghromium(II) Compounds. The Cr(II) salts of nonoxidizing mineral acids are prepared by the dissolution of pure electrolytic chromium metal ia a deoxygenated solution of the acid. It is also possible to prepare the simple hydrated salts by reduction of oxygen-free, aqueous Cr(III) solutions using Zn or Zn amalgam, or electrolyticaHy (2,7,12). These methods yield a solution of the blue Cr(H2 0)g cation. The isolated salts are hydrates that are isomorphous with and compounds. Examples are chromous sulfate heptahydrate [7789-05-17, CrSO 7H20, chromous chloride hexahydrate... 

The most stable solid hypochlorites are those of Li, Ca, Sr and Ba (see below). NaOCl has only poor stability and cannot be isolated pure KOCl is known only in solution, Mg yields a basic hypochlorite and impure Ag and Zn hypochlorites have been reported. Hydrated salts are also known. Solid, yellow, hydrated hypobromites Na0Br.xH20 (x = 5, 7) and K0Br.3H20 can be crystallized from solutions obtained by adding Br2 to cold cone solutions of MOH but the compounds decompose above 0°C. No solid metal hypoiodites have yet been isolated. 

Complexes with oxygen-donor ligands can be isolated as solids. The hydrated salts, Hg2(N03)2 2 H20 and Hg2(C104)2 -4 H20 both contain the aquo complex ion I ... 

The conventional preparative routes to anionic, neutral, or cationic complexes of indium start with the metal, which is dissolved in a suitable mineral acid to give a solution from which hydrated salts can be obtained by evaporation. These hydrates react with a variety of neutral or anionic ligands in nonaqueous solvents, and a wide range of indium(III) complexes have been prepared in this manner.1 Alternatively, the direct high-temperature oxidation of the metal by halogens yields the anhydrous trihalides, which are again convenient starting materials in synthetic work. In the former case, the initial oxidation of the metal is followed by isolation, solution reaction, precipitation, and recrystallization. 

Schreinemakers and de Baat s 4 study of the system Na20-As203-H20 afforded evidence of the formation of sodium pyroarsenile, Na4As2Os, both in the anhydrous state and as the hydrated salt, Na4As205.9H2O, but the isolation of these compounds in a pure form is difficult.5... 

The anhydrous salt, Co(C104)2, cannot be isolated since the hydrated salt decomposes before all the water has been expelled. 

Other promethium compounds that have been isolated include the hydroxide Pm(OH)3 [which adopts the 9-coordinate structure of Nd(OH)3] and hydrated salts including... 

All four scandium(III) halides are known, all but the fluoride (WO3 structure) having the FeCfr structure. They can be obtained as white solids directly from the elements and in some cases by dehydration of the hydrated salts, as well as by thermal decomposition of (NH4)3ScX6 (X = Cl, Br), a method also used for the lanthamdes. Gas-phase studies have identified isolated planar SCF3 molecules at 1750K ScCfr molecules with a very slight pyramidal distortion and both monomers and dimers in Scfr vapour at 1050 K. 

It was only in 1995 that the first structure of a hydrated salt of scandium containing only water molecules in its coordination sphere was reported. Refluxing scandium oxide with triflic acid leads to the isolation of hydrated scandium triflate Sc(03SCF3)3 9H20. It is isomorphous with the hydrated lanthanide triflates, containing tricapped trigonally prismatic coordinate scandium in the [Sc(H20)g] ions, with Sc—O (vertices) = 2.171(9) A and Sc—O (face capped) 2.47(2) A. 

The hexafluorophosphate ion has proved to be very useful for studies with complexes, since the [PF6] anion has a very weak coordinating ability.1 Lan-thanoid hexafluorophosphates can be obtained in very concentrated aqueous solutions by reaction of a freshly prepared solutions of hexafluorophosphoric acid and a hydrated lanthanoid basic carbonate.2 The resulting solution, after filtration, is evaporated to near dryness. Attempts to isolate the hydrated salts are unsuccessful because of decomposition accompanied by hydrogen fluoride evolution. Nevertheless, the complexes containing diphenylphosphinic amide are isolable and are quite stable.3... 

Materials Catalysts (5% metal content, pre-reduced in Ha at 3(XM(X) °C before use) and solvents were of commercial migin. Substrates and modifiers were either commercially available or prepared according to literature procedures. Benzylidenepyruvic acid was obtained by condensation of benzaldehyde and pyruvic acid in presence of KOH, the acid hydrate was isolated by pouring a warm, saturated solution of the K-salt into excess 2N aqueous HCl [4a]. 

Drying may also cause the thermally activated elimination of molecules other than the solvent. Depending on the temperature, hydrated salt crystallites dehydrate into, for example, hydroxynitrate phases [33, 37, 38] isolated complexes lose ligands and graft onto the support surface [39, 40] volatile compounds introduced in the impregnation solution as competitors or pH-adjusters evaporate (HCl, NH3). 

The complexes formed between Cu(II) ions and a number of D-aldonic and D-alduronic acids in aqueous solution has been studied, and the complex obtained from methyl a-D-mannopyranoside and copper(II) hydroxide in the presence of lithium hydroxide has been identified as the square planar structure 17. The determination of stability constants of Ca complexes with /wyo-inositol 1,4,5-trisphosphate is discussed in Chapter 18. The interaction of L-ascorbic acid with some metal ions has b n studied in aqueous solution at pH 6-7, and the solid hydrated salts lithium, sodium, potassium, ammcHiium, rubidium and cesium ascorbate have been isolated and characterised by C n.m.r. and f.t.ix. spectroscopy... 

A study of sucrose interactions with the same raagnesivun and calcium ions showed that both form mono- and di- sucrose adducts, and the isolation of several complexes formed between these metal ions and D-glucurono-1,4-lactone in ethanolic and aqueous solutions has been reported. The interaction in aqueous solution of j8-D-fructose with hydrated salts of Zn(II), Cd(Il), and Hg(ll) has given rise to solid adducts of the type M(D-fructose)Xa.nHaO, X = Br, Cl which were characterised by F.T.-I.R. spectroscopy. X-ray powder diffraction and molar conductivity measurements. Potentiometric pH titration was used to measure the stability constants of the 1 1 complexes formed between a number of cations and tubercidin 5 -monophosphate. The complexation ofCopper(II) ions with sucrose has been studied and a number of complexes were identified. A molecular model has been used to describe the formation of iron(III)-glucosamine complexes in aqueous KOH at various mole ratios. ... 

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