Halides aqueous solutions

Giaquinta, P. V., M. P. Tosi, and N. H. March (1983). Coordination chemistry and ionic solvation in divalent metal halide aqueous solutions. Phys. Chem. Liq. 13, 1-24. 

S.B. Farina, G.S. Duffo, J.R. Galvele, Stress corrosion cracking of zirconium and zircaloy-4 in halide aqueous solutions, Corros. Sci. 45 (2003) 2497—2512. 

Gavach, C. and N. Davion (1973). Interfacial potential and ion exchange equflih-rium between a potassium halide aqueous solution and an alkyltrimethyl ammonium picrate solution in nitrobenzene. Electrochim. Acta 18, 649-656. 

Hess B, van der Vegt NFA (2007) Solvent-averaged potentials for alkali-, earth alkali-, and alkylammonium halide aqueous solutions. J Chem Phys 127 234508 Collins KD (1997) Charge density-dependent strength of hydration and biological structure. Biophys J 72 65-76... 

A VTD, improved with a phase-locked loop for driving the oscillation (Majer et al, 1991b) was used by Wood and co-workers for measuring the pVTx properties of several metal halides aqueous solutions. Later, this group modified the VTD to improve its accuracy and reliability at higher temperatures. The Hastelloy U-tube was replaced by a platinum-rhodium alloy, more resistant to corrosion, and the new VTD assembly included two permanent magnets and soft-steel pole pieces to increases the magnetic field. The new VTD version was used in supercritical aqueous solutions up to 450 and 38 MPa. 

Fig. 6. SSP polarised SFG spectra of (a) 0.015 x NaF, (b) 0.015 x and0.036x NaCl, (c) 0.015 X and0.036x NaBr, and (d) 0.015 x and0.036x Nal. The neat water SFG spectrum is plotted in each figure for comparison. The open yellow and closed yellow triangles within (d) show the sum fi-equency intensity of the 0.015 x Nal in D20 and pure D20, respectively. Insets SFG sodium halide aqueous solutions spectral fits. Component Lorentzian peaks are shown as dashed pink lines, and the calculated fits from the component peaks are shown as black lines that go through most of the data points. (Reprinted with permission from Liu D, Ma G, Levering LM, Allen HC. (2004) JPhys Chem B 108 2252. Copyright 2004 American Chemical Society.)...

Soper AK, Weckstrom K. (2006) Ion solvation and water structure in potassium halide aqueous solutions. Biophys Chem 124 180-191. 

Rasaiah J C 1970 Equilibrium properties of ionic solutions the primitive model and its modification for aqueous solutions of the alkali halides at 25°C J. Chem. Phys. 52 704... 

The reactions with water are summarised in Table 6.3. Since the metals are powerful reducing agents (p. 98) they cannot be prepared in aqueous solution electrolysis of the fused anhydrous halides is usually employed using a graphite anode. 

C) Phenacyl and p-Bromophenacyl esters. Ammonium salts in aqueous-ethanolic solution do not however usually condense satisfactorily with phenacyl and />-bromophenacyl bromide. The aqueous solution of the ammonium salt should therefore be boiled with a slight excess of sodium hydroxide to remove ammonia, and the solution then cooled, treated with hydrochloric acid until just alkaline to phenol-phthalein, and then evaporated to dryness. The sodium salt is then treated as described (p. 349) to give the ester. Filter the ester, and wash with water to remove senium halide before recrystallisation. 

The diazonium salts 145 are another source of arylpalladium com-plexes[114]. They are the most reactive source of arylpalladium species and the reaction can be carried out at room temperature. In addition, they can be used for alkene insertion in the absence of a phosphine ligand using Pd2(dba)3 as a catalyst. This reaction consists of the indirect substitution reaction of an aromatic nitro group with an alkene. The use of diazonium salts is more convenient and synthetically useful than the use of aryl halides, because many aryl halides are prepared from diazonium salts. Diazotization of the aniline derivative 146 in aqueous solution and subsequent insertion of acrylate catalyzed by Pd(OAc)2 by the addition of MeOH are carried out as a one-pot reaction, affording the cinnamate 147 in good yield[115]. The A-nitroso-jV-arylacetamide 148 is prepared from acetanilides and used as another precursor of arylpalladium intermediate. It is more reactive than aryl iodides and bromides and reacts with alkenes at 40 °C without addition of a phosphine ligandfl 16]. 

Dextrin Polyethylene glycol 400 Use 5 mL of 2% aqueous solution of chloride-free dextrin per 25 mL of 0. IM halide solution. Prepare a 50% (v/v) aqueous solution of the surfactant. Use 5 drops per 100 mL end-point volume. 

Lithium Iodide. Lithium iodide [10377-51 -2/, Lil, is the most difficult lithium halide to prepare and has few appHcations. Aqueous solutions of the salt can be prepared by carehil neutralization of hydroiodic acid with lithium carbonate or lithium hydroxide. Concentration of the aqueous solution leads successively to the trihydrate [7790-22-9] dihydrate [17023-25-5] and monohydrate [17023-24 ] which melt congmendy at 75, 79, and 130°C, respectively. The anhydrous salt can be obtained by carehil removal of water under vacuum, but because of the strong tendency to oxidize and eliminate iodine which occurs on heating the salt ia air, it is often prepared from reactions of lithium metal or lithium hydride with iodine ia organic solvents. The salt is extremely soluble ia water (62.6 wt % at 25°C) (59) and the solutions have extremely low vapor pressures (60). Lithium iodide is used as an electrolyte ia selected lithium battery appHcations, where it is formed in situ from reaction of lithium metal with iodine. It can also be a component of low melting molten salts and as a catalyst ia aldol condensations. 

In general, hydrated borates of heavy metals ate prepared by mixing aqueous solutions or suspensions of the metal oxides, sulfates, or halides and boric acid or alkali metal borates such as borax. The precipitates formed from basic solutions are often sparingly-soluble amorphous soHds having variable compositions. Crystalline products are generally obtained from slightly acidic solutions. 

With Acyl Halides, Hydrogen Halides, and Metallic Halides. Ethylene oxide reacts with acetyl chloride at slightly elevated temperatures in the presence of hydrogen chloride to give the acetate of ethylene chlorohydrin (70). Hydrogen haUdes react to form the corresponding halohydrins (71). Aqueous solutions of ethylene oxide and a metallic haUde can result in the precipitation of the metal hydroxide (72,73). The haUdes of aluminum, chromium, iron, thorium, and zinc in dilute solution react with ethylene oxide to form sols or gels of the metal oxide hydrates and ethylene halohydrin (74). 

Acid Strength of the Hydrogen Halides in Aqueous Solution ... 

It is known that the order of acidity of hydrogen halides (HX, where X = F, Cl, Br, I) in the gas phase can be successfully predicted by quantum chemical considerations, namely, F < Cl < Br < I. However, in aqueous solution, whereas hydrogen chloride, bromide, and iodide completely dissociate in aqueous solutions, hydrogen fluoride shows a small dissociation constant. This phenomenon is explained by studying free energy changes associated with the chemical equilibrium HX + H2O + HjO in the solu-... 

Fonnation of allylic products is characteristic of solvolytic reactions of other cyclopropyl halides and sulfonates. Similarly, diazotization of cyclopropylamine in aqueous solution gives allyl alcohol. The ring opening of a cyclopropyl cation is an electrocyclic process of the 4 + 2 type, where n equals zero. It should therefore be a disrotatory process. There is another facet to the stereochemistry in substituted cyclopropyl systems. Note that for a cri-2,3-dimethylcyclopropyl cation, for example, two different disrotatory modes are possible, leading to conformationally distinct allyl cations ... 

Anhydrous beryllium halides cannot be obtained from reactions in aqueous solutions because of the formation of hydrates such as [Be(H20)4]F2 and the subsequent hydrolysis which attends attempted dehydration. Thermal decomposition of (NH4)2Bep4 is the best route for BeFr, and BeCl2 is conveniently made from the oxide... 

Similarly, the cyanide, acetate and carbonate are unstable in aqueous solution. Hydrolysis of the halides and other salts such as the nitrate and sulfate is incomplete but aqueous solutions are acidic due to the ability of the hydrated cation [AI(H20)6] to act as proton donor giving [A1(H20)5(0H)]-+, (AI(H20)4(0H)2]+, etc. If the pH is gradually increased this deprotonation of the mononuclear species is accompanied by aggregation via OH bridges to give species such as... 

Compounds of Tl have many similarities to those of the alkali metals TIOH is very soluble and is a strong base TI2CO3 is also soluble and resembles the corresponding Na and K compounds Tl forms colourless, well-crystallized salts of many oxoacids, and these tend to be anhydrous like those of the similarly sized Rb and Cs Tl salts of weak acids have a basic reaction in aqueous solution as a result of hydrolysis Tl forms polysulfldes (e.g. TI2S3) and polyiodides, etc. In other respects Tl resembles the more highly polarizing ion Ag+, e.g. in the colour and insolubility of its chromate, sulfide, arsenate and halides (except F), though it does not form ammine complexes in aqueous solution and its azide is not explosive. 

It is common practice to refer to the molecular species HX and also the pure (anhydrous) compounds as hydrogen halides, and to call their aqueous solutions hydrohalic acids. Both the anhydrous compounds and their aqueous solutions will be considered in this section. HCl and hydrochloric acid are major industrial chemicals and there is also a substantial production of HF and hydrofluoric acid. HBr and hydrobromic acid are made on a much smaller scale and there seems to be little industrial demand for HI and hydriodic acid. It will be convenient to discuss first the preparation and industrial uses of the compounds and then to consider their molecular and bulk physical properties. The chemical reactivity of the anhydrous compounds and their acidic aqueous solutions will then be reviewed, and the section concludes with a discussion of the anhydrous compounds as nonaqueous solvents. 

Lower oxidation states are rather sparsely represented for Zr and Hf. Even for Ti they are readily oxidized to +4 but they are undoubtedly well defined and, whatever arguments may be advanced against applying the description to Sc, there is no doubt that Ti is a transition metal . In aqueous solution Ti can be prepared by reduction of Ti, either with Zn and dilute acid or electrolytically, and it exists in dilute acids as the violet, octahedral [Ti(H20)6] + ion (p. 970). Although this is subject to a certain amount of hydrolysis, normal salts such as halides and sulfates can be separated. Zr and are known mainly as the trihalides or their derivatives and have no aqueous chemistry since they reduce water. Table 21.2 (p. 960) gives the oxidation states and stereochemistries found in the complexes of Ti, Zr and Hf along with illustrative examples. (See also pp. 1281-2.)... 

Iodide ions reduce Cu to Cu , and attempts to prepare copper(ll) iodide therefore result in the formation of Cul. (In a quite analogous way attempts to prepare copper(ll) cyanide yield CuCN instead.) In fact it is the electronegative fluorine which fails to form a salt with copper(l), the other 3 halides being white insoluble compounds precipitated from aqueous solutions by the reduction of the Cu halide. By contrast, silver(l) provides (for the only time in this triad) 4 well-characterized halides. All except Agl have the rock-salt structure (p. 242). Increasing covalency from chloride to iodide is reflected in the deepening colour white yellow, as the... 

Concentrated, aqueous solutions of ZnCla dissolve starch, cellulose (and therefore cannot be filtered through paper ), and silk. Commercially ZnCla is one of the important compounds of zinc. It has applications in textile processing and, because when fused it readily dissolves other oxides, it is used in a number of metallurgical fluxes as well as in the manufacture of magnesia cements in dental fillings. Cadmium halides are used in the preparation of electroplating baths and in the production of pigments. 

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