Lithium wire

A solution of methyl ithium in ether is prepared from lithium wire and methyl bromide according to the literature procedure, and titrated by the same method as Note 6. The checkers used 1.1 M methyl ithium from Aldrich. 

Although ethereal solutions of methyl lithium may be prepared by the reaction of lithium wire with either methyl iodide or methyl bromide in ether solution, the molar equivalent of lithium iodide or lithium bromide formed in these reactions remains in solution and forms, in part, a complex with the methyllithium. Certain of the ethereal solutions of methyl 1ithium currently marketed by several suppliers including Alfa Products, Morton/Thiokol, Inc., Aldrich Chemical Company, and Lithium Corporation of America, Inc., have been prepared from methyl bromide and contain a full molar equivalent of lithium bromide. In several applications such as the use of methyllithium to prepare lithium dimethyl cuprate or the use of methyllithium in 1,2-dimethyoxyethane to prepare lithium enolates from enol acetates or triraethyl silyl enol ethers, the presence of this lithium salt interferes with the titration and use of methyllithium. There is also evidence which indicates that the stereochemistry observed during addition of methyllithium to carbonyl compounds may be influenced significantly by the presence of a lithium salt in the reaction solution. For these reasons it is often desirable to have ethereal solutions... 

The submitters used lithium wire (Merck Company, Inc.) (12 in. = 1 g.) cut into small pieces for addition to the ammonia solution. The checkers used a block of lithium cut into small pieces. 

The lithium ethoxide solution is prepared by dissolving f.40 g. of lithium wire in 1 1. of anhydrous ethanol. 

To a solution of 1.38 g of estradiol 3-methyl ether (mp 118-119°) in 110 ml of anhydrous ether is added 140 ml of liquid ammonia followed by 1.4 g (42 eq per mole) of lithium wire in small pieces, and 10 min later 16 ml of absolute alcohol is added dropwise over a 10- to 20-min period. Occasionally frothing occurs during the last part of this addition but is easily controlled by stopping the stirrer temporarily. After removing most of the ammonia and carefully adding cold water, the product is extracted with ether, washed with Claisen alkali, water and saturated salt solution, and dried over sodium... 

While keeping the collected deuterioammonia at dry ice-isopropyl alcohol temperature, lithium wire (10 mg) is added, followed by a solution of 3/3-hydroxy-5a-cholest-7-en-6-one (161 50 mg) in anhydrous tetrahydrofuran (4 ml). The reaction mixture is stirred for 20 min, the cooling bath is then removed and the ammonia is allowed to boil under reflux for 40 min. A saturated solution of ammonium chloride in tetrahydrofuran is added dropwise until the deep blue color disappears and then the ammonia is allowed to evaporate. The residue is extracted with ether and the organic layer washed with dilute hydrochloric acid and sodium bicarbonate solution and then with water. Drying and evaporation of the solvent gives a semicrystalline residue which is dissolved in acetone and oxidized with 8 N chromic acid solution. After the usual workup the residue is dissolved in methanol containing sodium hydroxide (0.2 g) and heated under reflux for 1 hr to remove any deuterium introduced at C-5 or C-7. (For workup, see section II-B). 

I. Ethylamine, anhydrous EK Dimethylamine, anhydrous EK Lithium wire MCB... 

Lithium wire purchased from the Lithium Corporation of America, Inc. was used. The wire was cut in 2.5-5.0-cm. pieces, washed free of the protective oil with ether, and weighed by transferring quickly to a tared beaker containing mineral oil. The lengths of wire were again washed in a beaker of ether and then held with forceps over an open neck of the reaction flask (positive nitrogen flow), cut with scissors into 3-4-mm. pieces, and allowed to fall directly into the flask. 

Evidently surface area is important, since when the 15 cm. of lithium wire was added as 1-cm. pieces, the reduction was incomplete. Lithium wire (0.32 cm., 0.01% sodium) available from Alpha Inorganics, Inc. was wiped free of oil and rinsed with petroleum ether immediately prior to use. 

The lithium wire is cut into 0.5-cm. pieces and hammered to a foil immediately prior to use. 

Lithium wire is acceptable (but higher yields result with lithium sand dispersed in mineral oil) and requires in some cases a small amount of... 

Our entry into sonochemistry was spurred by our need for high yield preparations of symmetrical organics and bimetal lies. Our first efforts(16t17) with lithium wire were satisfactory but have since been greatly improved by using of lithium dispersion(18) ... 

Lithium wire (99% with 1% of sodium) was purchased from the Aldrich Chemical Company, Inc. The mineral oil is wipfed off with a paper towel before use. 

The lithium wire or ribbon is cut in about 0.25-g. pieces, stored under kerosene, and blotted with filter paper before addition. 

Generation in situ. Butyllithium (primary, secondary, or tertiary) can be generated by sonication of a mixture of lithium wire and a butyl chloride at 15° in dry THF. The corresponding butane is evolved under these conditions and LiCl precipitates the reaction is generally complete within 15 min. The highly useful lithium diisopropylamide can be prepared by sonication of a mixture of diisopropylamine, lithium, and butyl chloride in dry THF or ether. The yield is 91% and the solution can be used directly for deprotonation. Other lithium amides, even LiTMP, can be prepared in the same way. 

Chlorohydrins epoxides. Chloromethyllithium is thermally unstable, but can be obtained by reaction of lithium wire with bromochloromethane. The halide-lithium exchange is markedly accelerated by sonication [(( ], which also promotes a subsequent reaction of the chloromethyllithium with an aldehyde or a ketone to form epoxides via chlorohydrins.1 Overall yields are 70-90%. 

Lithium wire (3.2 mm dia., 0.02% Na, Alfa Products, Morton/Thiokol Inc.) is cut into 1-cm pieces, then washed with hexane and quickly weighed into a taped beaker of hexane. The checkers also used lithium shot (BDH) the lithium did not all dissolve at room temperature, and heating at 70°C for 5 hr was necessary to discharge the blue color. 

Caution. Tetrahydrofuran (THF) is extremely flammable and hygroscopic and forms explosive peroxides only anhydrous peroxide-free solvent should be used. Lithium wire is a hazardous substance and must be handled under strictly anaerobic conditions. Further, since it slowly reacts with dinitrogen at room temperature, lithium metal is best handled under an atmosphere of dry, oxygen-free argon. Vanadium trichloride is air-sensitive and should be transferred under an inert atmosphere. Carbon monoxide is a toxic and flammable gas and must be handled in a well-ventilated fume hood. 

Methylnaphthalene (40.5 mL, 285 mmol) is transferred via cannula to a stirred suspension of lithium wire, 3.2 mm diameter, cut into 2-mm lengths (1.34 g, 193 mmol) in 200 mL of anhydrous THF in a 1-L round-bottomed flask, equipped with a sidearm stopcock for attachment to the vacuum line and a... 

A 50 mL, flame dried round-bottomed flask equipped with a magnetic stirrer bar and a 3-way tap with argon balloon was charged with lithium wire (70 mg, 10 mmol) and 4,4 -di-ferf-butylbiphenyl (2.25 g, 8.45 mmol). Distilled tetrahy-drofuran (25 mL) was then added at room temperature. After stirring for 10 min at room temperature, the mixture was cooled to 0 °C. The stirring was continued for 1 h at 0 °C to afford di-ferf-butylbiphenyllithium (LDBB) solution in THE (25 mL). 

Note (a) Lithium wire should be washed by hexane, and cut into small pieces under argon. 

To a dry flask containing 415 ml of n-propylamine and 10.15 gm (1.45 gm-atoms) of chopped lithium wire segments is added, with stirring, 21.3 gm (0.125 mole) of l-methyl-l,2,3,4-tetrahydroquinoline, and the mixture is stirred for 16J hr under a nitrogen atmosphere. The un reacted lithium is removed, the excess n-propylamine is distilled from the flask, the semisolid residue is cooled in an ice bath, overlaid with ether, and then neutralized slowly with solid ammonium chloride. The mixture is cautiously diluted with water, the ether layer separated, the water layer extracted with ether, the ether layers combined, dried, concentrated, and the residue is distilled to alford 19.8 gm... 

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