Preparation of Lithium Peroxide

Preparation of Lithium Peroxide, a. Preparation o/ Lithium Hydroxide Monohydrate. Put 5 g of lithium sulphate into a 400-ml 

Separate the precipitate from the solution by filtration through a smooth filter (fine-texture filter paper—Whatman No. 2 or Schleicher and Schnell No. 489 Blue Ribbon). Transfer the filtrate into a 

Rapidly transfer the solution into a bowl and cool it to room temperature. Filter off the precipitated crystals using a glass filter No. 3 (about 400 mesh). 

Separate the formed precipitate of lithium peroxide monohydrate from the mother liquor by filtration and wash it twice on the filter with 5-ml portions of absolute ethanol. Dry the substance in the air. 

Add distilled water to a small amount of the lithium peroxide. See how the mixture reacts with solutions of potassium permanganate and potassium iodide acidified with sulphuric acid (add two nr three drops of a starch size to,the potassium iodide solution). What do you observe Write the equations of the reactions. 

Wurtz flask connected to a water-jet pump. Place the flask in a water bath and evaporate the solution in the vacuum produced by the pump up to a volume of about 20 ml. 

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Lithium Oxide. Lithium oxide [12057-24-8], Li20, can be prepared by heating very pure lithium hydroxide to about 800°C under vacuum or by thermal decomposition of the peroxide (67). Lithium oxide is very reactive with carbon dioxide or water. It has been considered as a potential high temperature neutron target for tritium production (68). 

The relevant properties of peroxide and superoxide salts are given in Table 4 (see Peroxides and peroxide compounds, inorganic). Potassium peroxide is difficult to prepare and lithium superoxide is very unstable. The ozonides, MO3, of the alkah metals contain a very high percentage of oxygen, but are only stable below room temperature (see Ozone). 

Vinylic lithium reagents (26) react with silyl peroxides to give high yields of silyl enol ethers with retention of configuration. Since the preparation of 26 from vinylic halides (12-37) also proceeds with retention, the overall procedure is a... 

The preparation of Pans-1,2-cyclohexanediol by oxidation of cyclohexene with peroxyformic acid and subsequent hydrolysis of the diol monoformate has been described, and other methods for the preparation of both cis- and trans-l,2-cyclohexanediols were cited. Subsequently the trans diol has been prepared by oxidation of cyclohexene with various peroxy acids, with hydrogen peroxide and selenium dioxide, and with iodine and silver acetate by the Prevost reaction. Alternative methods for preparing the trans isomer are hydroboration of various enol derivatives of cyclohexanone and reduction of Pans-2-cyclohexen-l-ol epoxide with lithium aluminum hydride. cis-1,2-Cyclohexanediol has been prepared by cis hydroxylation of cyclohexene with various reagents or catalysts derived from osmium tetroxide, by solvolysis of Pans-2-halocyclohexanol esters in a manner similar to the Woodward-Prevost reaction, by reduction of cis-2-cyclohexen-l-ol epoxide with lithium aluminum hydride, and by oxymercuration of 2-cyclohexen-l-ol with mercury(II) trifluoro-acetate in the presence of ehloral and subsequent reduction. ... 

Analogously, for preparation of racemic carba-a-glucopyranose 49 from 52, esterification of (—)-52 furnished the ester 95, which was transformed into compound 96 by debromination with zinc dust and acetic acid. Stereoselective hydroxylation of 96 with osmium tetraoxide and hydrogen peroxide, followed by acetylation, gave compound 97. Lithium aluminum hydride reduction of 97, and acetylation of the product, gave pentaacetate 98, which was converted into 99 by hydrolysis. ... 

Run a similar experiment with metallic lithium. What forms in this case How can lithium peroxide be prepared What products form when rubidium and cesium react with the oxygen of the air ... 

An improved route to 2a-hydroxycholesterol has been devised as part of the preparation of 2a-hydroxy-vitamin D3 (263 R1 = R4 = R5 = R6 = H, R2 = R3 = OH).123 Hydroxylation of the A bond of cholesta-l,5-dien-3/3-ol by means of 9-borabicyclo[3,3,l]nonane followed by reaction with alkaline hydrogen peroxide produced the 2-equatorial 2a,3a-diol in 70—80% yield. The conventional four-step sequence, acetylation, bromination, dehydrobromination, and hydrolysis, gave 2a -hydroxycholesta-5,7-dien-3/3-ol which was converted into 2a-hydroxy-vitamin D3. The isomeric 2/3-hydroxy-vitamin D3 has also been reported.124 Reaction of the 1/6,2/3-oxide obtained by peroxidation of the adduct (265) with lithium aluminium hydride results in a mixture of 2/3,3/3-dihydroxycholest-5,7-diene and its 1/3,3/3-dihydroxy-epimer in the ratio 8 1. Irradiation of the former 5,7-diene furnished the expected previtamin, which on equilibration gave 2/3-hydroxy-vitamin D3 (263 R1 = R4 = R5 = R6 = H, R2 = a-OH, R3 = OH). 

As shown in equation 2, the lithium enolate oxidation with O2, followed by sodium sulphite reduction, has been applied with success to oxidation of the enolate derived from 1 the nature of the reducing agent has been decisive for the direct preparation of the hepatoprotective agent Clausenamide (2). As a matter of fact, 2 forms when the treatment with O2 is done in the presence of triethyl phosphite as reducing agent, whereas sodium sulphite reduction affords compound 3. It has been postulated that the transformation 1 —3 occurs through the intermediacy of the peroxide 4. 

Dibenzyl peroxydicarbonate has been used for the oxidation of both chiral and achiral lithium or potassium enolates to form carbonates of a-hydroxy carbonyl compounds. Dibenzyl peroxydicarbonate, prepared from aqueous hydrogen peroxide and benzyl chlo-roformate under basic conditions, was preferred for mechanistic studies to the commonly used MoOPH in view of the easier preparation of 0-labelled compounds . 

Lithium acetylides 28 are oxygenated by lithium t-butylperoxide, prepared from anhydrous t-butylhydroperoxide and LHMDS, to give lithium ynolates 29 (equation 9) °. This method has been used as an efficient route for the preparation of the silyl ynolates 30" (Section V). Dioxygen, t-butyl perborate and bis(trimethylsilyl)peroxide have been unsuccessful as oxidation reagents " . ... 

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