Dilithium acetylide

Dicaesium acetylide Copper(ll) acetylide Dicopper(l) acetylide Silver acetylide Caesium acetylide Potassium acetylide Lithium acetylide Sodium acetylide Rubidium acetylide Lithium acetylide-ammonia Dipotassium acetylide Dilithium acetylide Disodium acetylide Dirubidium acetylide Strontium acetylide Silver trifluoromethylacetylide Sodium methoxyacetylide Sodium ethoxyacetylide... 

Lithium reacts with acetylene in liquid ammonia solution to give the mono and dilithium acetylides, LiC=CH and LiC=CLi, with the evolution of hydrogen, which illustrates the slight acidity of acetylene. One commercial use of LiC=CI I is in one step of the synthesis of vitamin A. 

Acetylene gas must be removed from above the solution to prevent reaction with the concentrated butyllithium solution entering the flask. Such a reaction in the presence of excess butyllithium will result in the formation of dilithium acetylide on the needle tip. The formation of even small amounts of dilithium acetylide must be avoided lithium acetylide readily... 

Lithium Carbide or Monolithium Acetylide, LiC, wh crysts, d 1.65 at 18° was prepd by Moissan on heating Li carbonate with 6 mols of sugar-charcoal in an elec furnace Li2COs + 6C - 2LiCj + 3CO(Ref 2). It is a powerful reducing agent and reacts with w in cold to produce pure C,Ha and the reaction becomes violent at ca lOO tsee also Dilithium Acetylide listed below Refs l)Beil 1,238 2)H.Moissan, CR... 

Dilithium ethyneditellurolate was obtained in reactions of monolithium acetylide or of dilithium acetylide with tellurium in tetrahydrofuran containing 1,2-diaminoethane (DAE)4. The ditellurolate was reacted with methyl iodide to produce methyltelluroelhynyl methyl telluride in good yields based on tellurium employed. The surprising formation of the ditellurolate from the monolithium acetylide was explained by the disproportionation of monolithium acetylide into dilithium acetylide and acetylene4. 

Another route to lithium acetylide involves heating lithium with graphite in a bomb or tube above 850° to form dilithium acetylide, a yellow to light grey refracting material which can be ground to a fine powder.7 Dilithium acetylide reacts with acetylene in liquid ammonia rapidly to give a clear solution of lithium acetylide. 

Butyllithium must be added slowly to an excess of the efficiently stirred acetylene solution at -78 C. Localized warming of the solution or rapid introduction of butyllithium to produce a local excess of base must be avoided in order to prevent the formation of the unreactive and insoluble dilithium acetylide which will be observed as a cloudy suspension. Reaction of ketones or aldehydes with a cloudy suspension of dilithium acetylide results in substantially lowered yields of the carbinol products. ... 

Ethynylcarbinols. Lithium acetylide can be prepared in high yield as a solution in THF by addition of n-butyllithium to acetylene at -78°. If the solution is allowed to warm to 0°, a white precipitate of dilithium acetylide is formed by disporportionation. High yields of ethynylcarbinols can be obtained by reaction of aldehydes or ketones with the solution of lithium acetylide in THF at -78. Lithium acetylide stabilized with ethylenediamine is less reactive than the reagent stabilized with THF. ... 

The Diels-Alder reaction of a-pyrone with bis(trimethylsilyl)acetylene, obtained from dilithium acetylide and trimethylsilyl chloride, gives o-bis(trimethylsilyl)benzene by spontaneous decarboxylation of the initial adduct (equation 59). ... 

In stage I, metallic lithium is dissolved in liquid ammonia at its boiling point (ca. -33 °C). Acetylene is then fed to this solution, first forming dilithium acetylide ( lithium carbide ). Lithium carbide then reacts further with acetylene to form monolithium acetylide and ethylene. In stage II, the vinyl ketone, diluted with an organic... 

Because silicon is able to conjugate electronically with adjacent alkyne n bonds, poly(silylenealkynylene)s, (SiR2C=C)n (9), can be expected to exhibit conducting or nonlinear optical properties. A very efficient method to synthesize poly(silyleneethynylene) has been reported. Dilithium acetylide prepared from trichloroethylene and butyllithium was treated with Cl2SiR2 to give high molecular weight polymers (Mw = 30,000, when R = CeHs M = 20,000, when R = CeHs, CH3) (eq. 9) (74). 

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