Solubility, lithium chloride effects

The thermodynamic excess functions for the 2-propanol-water mixture and the effects of lithium chloride, lithium bromide, and calcium chloride on the phase equilibrium for this binary system have been studied in previous papers (2, 3). In this paper, the effects of lithium perchlorate on the vapor-liquid equilibrium at 75°, 50°, and 25°C for the 2-propanol-water system have been obtained by using a dynamic method with a modified Othmer still. This system was selected because lithium perchlorate may be more soluble in alcohol than in water (4). 

Salt effects of lithium chloride and calcium chloride on the solubility of carbon dioxide in a mixture of methanol and water were observed at 25°C and 1 atm. Experimental results can be correlated by the Setschenow equation for a fixed solvent composition of salt-free basis. The salting-out parameter is not linear with solvent composition, which is opposite to the results obtained when a mixed salt is used. 

In the present investigation, the salt effects of lithium chloride and calcium chloride on the solubility of carbon dioxide in the mixed solvents of methanol and water were experimentally studied at 25°C and 1 atm. 

Effect of Cation. Of all alkali chlorides, only lithium chloride is sufficiently soluble in ethylenediamine to act as an electrolyte. On the other hand, all alkali iodides are soluble in ethylenediamine. Since the anion has a large effect on current efficiency, a common anion such as the iodide ion must be used to compare the effect of the various cations. The results of runs 6 and 7 show that the current efficiency was slightly higher and the percentage of octalin formed much greater when rubidium iodide was used instead of lithium iodide. The metallic cations Li and Rb give markedly better current efficiency than the organic cations (runs 6, 7, 8, and runs 5, 9, 10, 11). 

Thus lithium chloride is the most effective of those listed in producing a dry solvent, but it is very water soluble and therefore large quantities are needed to produce a saturated solution. It is also one of the more expensive of the solids listed and, in any particular combination of solvent purchase cost, water present and other drying means available, NaCl or Na2S04 is likely to be the most economic for an industrial process. 

Dimethyl disulfide traps organometallic species very effectively. For example, it converts the poorly soluble lithium 3-lithio-2-naphthoate into 3-methylthio-2-naphthol in 83% yield. Treated with the same reagent, iV,0-dilithiated ter/-butyl- -phenyl-carbamate furnishes the methyl sulfide in 89% yield. The smelly workup can be avoided if dimethyl disulfide is replaced by diphenyl disulfide, sulfur di-chloride, or di(benzenesulfonyl)sulfide. Particularly clean reactions are achieved with thio-A,A -diimidazole (83, Scheme 1-58). ... 

Source of Chloride Nucleophile. The solubility of LiCl in many organic dipolar solvents renders it an effective source of nucleophilic chloride anion. Lithium chloride converts alcohols to alkyl chlorides under Mitsunobu conditions, or by way of the corresponding sulfonates or other leaving groups. This salt cleanly and regioselectively opens epoxides to chlorohydrins in... 

Anionic polymerization of vinyl monomers can be effected with a variety of organometaUic compounds alkyllithium compounds are the most useful class (1,33—35). A variety of simple alkyllithium compounds are available commercially. Most simple alkyllithium compounds are soluble in hydrocarbon solvents such as hexane and cyclohexane and they can be prepared by reaction of the corresponding alkyl chlorides with lithium metal. Methyllithium [917-54-4] and phenyllithium [591-51-5] are available in diethyl ether and cyclohexane—ether solutions, respectively, because they are not soluble in hydrocarbon solvents vinyllithium [917-57-7] and allyllithium [3052-45-7] are also insoluble in hydrocarbon solutions and can only be prepared in ether solutions (38,39). Hydrocarbon-soluble alkyllithium initiators are used directiy to initiate polymerization of styrene and diene monomers quantitatively one unique aspect of hthium-based initiators in hydrocarbon solution is that elastomeric polydienes with high 1,4-microstmcture are obtained (1,24,33—37). Certain alkyllithium compounds can be purified by recrystallization (ethyllithium), sublimation (ethyllithium, /-butyUithium [594-19-4] isopropyllithium [2417-93-8] or distillation (j -butyUithium) (40,41). Unfortunately, / -butyUithium is noncrystaUine and too high boiling to be purified by distiUation (38). Since methyllithium and phenyllithium are crystalline soUds which are insoluble in hydrocarbon solution, they can be precipitated into these solutions and then redissolved in appropriate polar solvents (42,43). OrganometaUic compounds of other alkaU metals are insoluble in hydrocarbon solution and possess negligible vapor pressures as expected for salt-like compounds. 

Solid lithium aluminium hydride can be solublized in non-polar organic solvents with benzyltriethylammonium chloride. Initially, the catalytic effect of the lithium cation in the reduction of carbonyl compounds was emphasized [l-3], but this has since been refuted. A more recent evaluation of the use of quaternary ammonium aluminium hydrides shows that the purity of the lithium aluminium hydride and the dryness of the solvent are critical, but it has also been noted that trace amounts of water in the solid liquid system are beneficial to the reaction [4]. The quaternary ammonium aluminium hydrides have greater hydrolytic stability than the lithium salt the tetramethylammonium aluminium hydride is hydrolysed slowly in dilute aqueous acid and more lipophilic ammonium salts are more stable [4, 5]. 

The largest solubility isotope effects are found for sparingly soluble salts. For example, lead chloride and potassium bichromate are 36% and 33.5% more soluble in H20 than D20 at 298.15 and 278.15 K, respectively. For the more soluble salts, NaCl and KC1, the values are 6.4% and 9.0%. Interestingly LiF and LiCl.aq have inverse effects of 13% and 2%, respectively. Recall that lithium salts are commonly designated as structure makers . Almost all other electrolytes are structure breakers . 

According to the ionic hypothesis, if the solubility product [Li]2[C0"3] is not altered, the solubility can be increased by the union of one or other of the ions of the carbonate forming complexes with the added salt. This effect is not very marked with potassium or sodium chloride or nitrate. The marked increase in the solubility with sodium and potassium sulphates is due to the formation of lithium sulphate, but with the ammonium salts soluble complexes like Li(NH3) and NH2C00 may be formed just as is the case with magnesium carbonate in the presence of ammonium salts. 

Anionic polymerization of vinyl monomers can be effected with a variety of organomciallic compounds alkyllithium compounds are the most useful class. A variety of simple alkyllithium compounds are available commercially. Most simple alkyllithium compounds ate soluble in hydrocarbon solvents such as hexane and cyclohexane and they can be prepared by reaction of the corresponding alkyl chlorides with lithium metal. 

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