Lithium carbonate, purification

Lithium carbonate Lithium carbonate is synthesized by reacting lithinm salts with soda or potash, followed by purification of the salt, which is not readily solnble [75]. 

Since lithium salts obtainable by purchase, even of so-called c.p. or reagent quality, frequently contain impurities totaling about 1 per cent, it is desirable to have a rapid method for obtaining such salts in a reasonably pure state. The following simple procedure for the purification of c.p. or reagent grade lithium carbonate provides such a method, since the resulting pure carbonate may be readily converted by treatment with the proper pure acid into practically any lithium salt desired. The procedure is based upon the fact that lithium carbonate, in contrast to the salts that contaminate it, is much less soluble in hot than in cold water. J In other words, simple recrystallization is employed, but the process is carried out in the reverse direction. 

Lanthanum nitrate, analysis of anhydrous, 5 41 Lead (IV) acetate, 1 47 Lead(II) 0,0 -diethyl dithiophos-phate, 6 142 Lead (IV) oxide, 1 45 Lead(II) thiocyanate, 1 85 Lithium amide, 2 135 Lithium carbonate, formation of, from lithium hydroperoxide 1-hydrate, 5 3 purification of, 1 1 Lithium chloride, anhydrous, 6 154 Lithium hydroperoxide 1-hydrate, 5 1... 

Lithium carbonate, Li2C03.—The carbonate is prepared by boiling a solution of a lithium salt with ammonium, sodium, or potassium carbonate, its slight solubility inducing crystallization and facilitating purification. A process for its manufacture from lepidolite has also been devised.2... 

The coke materials discussed so far are made from coal. They are sometimes also called active carbon , if they are employed for purification processes. Capacities as high as 300 Ah/kg are reported in the literature [189]. Some papers are of special interest, for a broad spectrum of graphites and carbons were evaluated in the same laboratory [190,191]. Figure 21 shows that lithium-carbons are characterized by discharge curves with potentials which comprise a broader potential region of 0.1-1V vs. Li. The lithium-graphite potential is held at 0.1-0.3 V vs. Li, as mentioned above. 

The most generally accessible machine is the nuclear reactor, and large activities of F can be induced by the neutron bombardment of oxygen salts of lithium [reaction (3)]. Lithium carbonate is the most convenient oxygen salt because of its high thermal stability (temperatures around 250° are developed by self-heating of lithium salts in an intense neutron flux), its ease of purification (since lithium carbonate has a negative temperature coeflScient of solu-... 

The purification of lithium carbonate by taking advantage of its negative coefficient of solubility has been described by E. R. Caley and P. J. Elving, Inorganic Syntheses, 1, 1 (1939). 

An alternative route was also developed for the synthesis of ( )-pisiferic acid (196) as described in "Fig (17)". The starting material for the present synthesis was the already described alcohol (15), which on tetrahydropyranylation yielded the derivative (197). Metal hydride reduction of (197) afforded a mixture of alcohols whose tosyl derivative on heating with lithium bromide and lithium carbonate in dimethylformamide afforded the oily olefin (198). These conditions not only provoked the dehydrosulphonation but also the hydrolysis of the tetrahydropyranyl group, thus shortening the reaction sequence by one step. The oily olefin (198) on oxidation yielded the ketone (199), which was formylated, and subjected to Robinson annelation with methyl vinyl ketone prepared in situ following the procedure of Howell and Taylor [74]. The resulting adduct without purification was heated by boiling with sodium methoxide in methanol to obtain the tricyclic ketone (200). It was treated with... 

Zintl, Harder and Dauth prepared LigO by thermal decomposition of pure LigCOg. Pure lithium carbonate (for purification see p. 987) is decomposed in a Pt boat set inside a porcelain tube which is connected to a mercury diffusion pump. Gas evolution ceases after heating for 50 hours at 700°C, as indicated by a McLeod gauge. The boat then contains pure white oxide, the composition of which can be checked by titration of samples. 

Another air-purification method for enclosed spaces involves the use of scrubbers containing aqueous lithium hydroxide, which reacts with carbon dioxide to produce lithium carbonate and water ... 

Dimethylphenylsilyl lithium (1 mmol, above THF solution) was added to copper(i) iodide (0.5 mmol) at — 23 °C, and the mixture was stirred at this temperature for 4h. The enone (0.75-0.5mmol) was then added, and stirring was continued at —23 °C for 0.5 h. The mixture was then poured on to ice(25 g)/HCl(5 ml), and extracted with chloroform (3 x 25 ml). The combined extracts were filtered, washed with HCI (25ml, 3m), water (25 ml), saturated sodium hydrogen carbonate solution (25 ml) and water (25 ml), and dried. Concentration and purification by preparative t.l.c. (eluting solvent 3 7 ether petrol) gave the /J-silylketone (40-99%). 

Precipitate with aq. ammonia. Evaporate the soln. down to about 100 c.c., and filter the ot liquid so as to remove calcium sulphate. The cone. soln. is sat. with ammonium alum and allowed to stand for some time. The mixed crystals of potassium, rubidium, and oeesium alums and of lithium salt are dissolved in 100 c.c. of distilled water and recrystal-lized. The recrystallization is repeated until the crystals show no spectroscopic reaction for potassium or lithium. The yield naturally depends on the variety of lepidolite employed. 100. grms of an average sample gives about 10 grms. of crude crystals and about 3 grms. of the purified caesium and rubidium alums. For the purification of caesium and rubidium salts, see the chlorides. The mother-liquors are treated with an excess of barium carbonate, boiled, and filtered. The filtrate is acidified with hydrochloric acid, and evaporated to dryness. The residue is extracted with absolute alcohol in which lithium chloride is soluble, and the other alkali chlorides are sparingly soluble. 

Lithium wire (3.2 mm diam.), carbon tetrachloride, triphenylphosphine, MgBrEtaO, copper bromide-dimethyl sulfide complex, hexanoyl chloride, methyllithium, p-toluenesulfonic acid monohydrate, potassium hydride, and 18-crown-6 were purchased from Aldrich Chemical Company, Inc. and used without further purification. 

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