Lithium bromide hydrates

In 1953 Olson and Konecny (19) studied the conductance of lithium bromide in acetone-water mixtures at 25°C and 35°C. They calculated KD and Ao in the acetone-rich solvents by the Fuoss method and Ao in the water-rich solvents by extrapolation of the phoreogram. They found that as the water content increases Kd increases, Ao decreases but then undergoes an increase, and a increases from slightly less than the sum of the crystal ionic radii to the sum of the radii of the fully hydrated ions. Extrapolation of their data for A0 to zero water content is not reliable because of the large concave upward negative slope however, it would appear to lead to a value of about 220 U l cm2 eq-1. Similar extrapolations of values for Kd and a yield 2.0 X 10 4 and 2.2 A, respectively. 

Lithium bromide. C.AS 7550-35-8) LiBr. mp 550 C, soluble in HyO or alcohols. The compound is very hygroscopic and forms four hydrates. Major use has heen in ubsoiplion-refrigeration air-conditioning systems in which H-O is the refrigerant—strong LiBr is used to absorb HyO vapor. 

I A//soi te I < I A//hydrationl The amount of energy required to separate the solute into its constiment ions is less than the energy given off when the ions are hydrated. AHsoin is therefore negative, and the solution process is exothermic. Solutes with negative enthalpies of solution include lithium bromide and potassium hydroxide. When these solutes dissolve in water, the resulting solutions feel warm to the touch. 

Lithium Chloride. Of the metal haUdes, calcium bromide [7789-41-5] CaBr2, ziac chloride [7646-85-7] ZnCl2, CaCl2, and lithium chloride [7447-41-8] LiCl, (Class 1, nonregenerative) are the most effective for water removal (4). AH are available ia the form of dehquescent crystals. The hydrates of LiCl are LiCl-nH2 O, where n = 1, 2, or 3. Lithium chloride solutions are more stable ia air and less corrosive than the other metal haUdes. The high solubihty of lithium carbonate [554-13-2] Li2C02, usually eliminates scale formation problems (see LiTHlUM COMPOUNDS). 

Elemental composition (Anhydrous LiBr) Li 7.98%, Br 92.02%. The water of crystallization in hydrated salt can be measured by gravimetry. Lithium and bromide ions may be analyzed in diluted aqueous solutions of the salt by AA or ICP spectroscopy and ion chromatography, respectively. 

Silver perchlorate forms deliquescent crystals, which decompose when heated to 486 Celsius. It is freely soluble in water saturated solution contains 85% by weight silver perchlorate making it one of the most water soluble compounds known lithium perchlorate being number 1. It is also soluble in aniline, pyridine, benzene, nitromethane, glycerol, and chlorobenzene. It can form solvated crystals with aniline, benzene, and toluene all explode on percussion. Silver perchlorate forms a hydrate, which melts at 43 Celsius. It can be made by reacting sodium hypochlorite (bleach) with silver bromide. 

Most ionic halides dissolve in water to give hydrated metal ions and halide ions. However, the lanthanide and actinide elements in the +3 and +4 oxidation states form fluorides insoluble in water. Fluorides of Li, Ca, Sr, and Ba also are sparingly soluble, the lithium compound being precipitated by ammonium fluoride. Lead gives a sparingly soluble salt PbCIF, which can be used for gravimetric determination of F . The chlorides, bromides, and iodides of Ag1, Cu1, Hg1, and Pbn are also quite insoluble. The solubility through a series of mainly ionic halides of a... 

Lithium iodide forms a solid complex with ammonia, Li(NH3)4l, but the related hydrate, alcoholate and amine complexes are less stable. These complexes presumably involve ion-dipole bonds (p. 115), the nitrogen lone pairs surrounding the Li+ some covalent character (dative bonding) is also permissible if s and p orbitals on the Li are invoked. The chloride, bromide and iodide of lithium are much more soluble in alcohol and ether than those of the other alkali metals, but this is not always a reliable indication of covalent character. The property is employed in separating lithium from sodium. 

Treatment of lithium acetylide with a primary alkyl halide (bromide or iodide) or with aldehydes or ketones produces the corresponding monosubstituted acetylenes or propargylic alcohols. Mercuric ion-catalyzed hydration of these furnishes methyl ketones and methyl a-hydroxy ketones, respectively. 

The unusual cyclopropane 551 was isolated [probably as the (5)-isomer] from Pistacia vera, together with the hydrated analog 552 551 was synthesized by Grignard reaction of cyclopropylmagnesium bromide with 4-methyl-3-cyclohexenone, and the diol 552 by lithium aluminum reduction of the epoxide of 551. ... 

The cyclic vinyl ether 2,3-dihydro-1,4-dioxin is converted into its cyclic hemiacetal hydration product, tetrahydro-2-hydroxy-1,4-dioxin, in aqueous solution by an acid-catalyzed reaction <870K2746, 89JP043). Treatment of an alcohol with excess of 2,3-dihydro-1,4-dioxin at room temperature in the presence of copper(II) bromide in tetrahydrofuran leads to the corresponding acetal. This new protective group for alcohols, which is stable towards lithium aluminum hydride and organolithium reagents, can be removed by treatment with acidified aqueous methanol <85S806>. 

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