Lithium metal acetylene

Lithium acetyhde also can be prepared directly in hquid ammonia from lithium metal or lithium amide and acetylene (134). In this form, the compound has been used in the preparation of -carotene and vitamin A (135), ethchlorvynol (136), and (7j--3-hexen-l-ol (leaf alcohol) (137). More recent synthetic processes involve preparing the lithium acetyhde in situ. Thus lithium diisopropylamide, prepared from //-butyUithium and the amine in THF at 0°C, is added to an acetylene-saturated solution of a ketosteroid to directly produce an ethynylated steroid (138). 

In a related reaction, heating ketones in the presence of TlClsOTf leads to 1,3,5-trisubstituted arenes. " Nitriles react with 2 mol of acetylene, in the presence of a cobalt catalyst, to give 2-substituted pyridines. " Triketones fix nitrogen gas in the presence of TiCU and lithium metal to form bicyclic pyrrole derivatives. " ... 

Benkeser and Tincher 128>, on the other hand, reduced acetylenes preferentially to trans olefins using solvated electrons generated at a platinum cathode by electrolytic reduction of lithium chloride in methylamine [lithium metal is formed from lithium ion at the cathode in this electrolysis its dissolution in methylamine generates the solvated electron and regenerates lithium... 

Both the lithium sulfur dioxide (Li-SO and lithium thionyl chloride (Li-SOCy cells may be classified as liquid cathode systems. In these systems, S02 and SOCl2 function as solvents for the electrolyte, and as the active materials at the cathode to provide voltage and ampere capacity. As liquids, these solvents permeate the porous carbon cathode material. Lithium metal serves as the anode, and a polymer-bonded porous carbon is the cathode current collector in both systems. Both cells use a Teflon-bonded acetylene black cathode structure with metallic lithium as the anode. The Li-S02 is used in a spirally wound, jelly-roll construction to increase the surface area and improve... 

This synthetic route can be usefiil for organic molecules with exceptionally acidic protons, such as acetylenes or cyclopentadienes. These reactions often require the alkali metal to be present as very small particles. Sodium sand can be formed by refluxing in THF with minor agitation to break up the sodium into tiny particles. Reactions with potassium may require a mirror that can be formed by dissolving potassium metal in liquid ammonia followed by evaporation of the ammonia from the reaction vessel. Ultrasound has also been used to aid in the formation of organolithium compounds from lithium metal. 

A modification of the acetylene zipper method employs lithium 3-amino-propylamide and circumvents the use of potassium hydride. The reagent is prepared by adding lithium metal to APA followed by addition of r-BuOK. " ... 

Phenyl substituted ethylenes, acetylenes, and allenes are known to add lithium metal — sometimes with dimerization — to yield stable benzyl-type 1,2- or 1,4-dilithium compounds, respectively. The first observations in this connection already go back to Schlenk and Bergmann in 1928. 

IODINE (7553-56-2) A powerful oxidizer. Material or vapors react violently with reducing agents, combustible materials, alkali metals, acetylene, acetaldehyde, antimony, boron, bromine pentafluoride, bromine trifluoride, calcium hydride, cesium, cesium oxide, chlorine trifluoride, copper hydride, dipropylmercury, fluoride, francium, lithium, metal acetylides, metal carbides, nickel monoxide, nitryl fluoride, perchloryl perchlorate, polyacetylene, powdered metals, rubidium, phosphorus, sodium, sodium phosphinate, sulfur, sulfur trioxide, tetraamine, trioxygen difluoride. Forms heat- or shock-sensitive compounds with ammonia, silver azide, potassium, sodium, oxygen difluoride. Incompatible with aluminum-titanium alloy, barium acetylide, ethanol, formamide, halogens, mercmic oxide, mercurous chloride, oxygen, pyridine, pyrogallic acid, salicylic acid sodium hydride, sodium salicylate, sulfides, and other materials. 

MERCURIO (Italian, Spanish) (7439-97-6) Violent reaction with alkali metals, aluminum, acetylenic compounds, azides, boron phosphodiiodide (vapor explodes), bromine, 3-bromopropyne, chlorine, chlorine dioxide, ethylene oxide, lithium, metals, methyl silane (when shaken in air), nitromethane, peroxyformic acid, potassium, propargyl bromide, rubidium, sodium, sodium carbide. Forms sensitive explosive products with acetylene, ammonia (anhydrous), chlorine, picric acid. Increases the explosive sensitivity of methyl azide. Mixtures with hot sulfuric acid can be explosive. Incompatible with calcium, sodium acetylide, nitric acid. Reacts with copper, silver, and many other metals (except iron), forming amalgams. 

EXPLOSION and FIRE CONCERNS noncombustible slightly volatile at ordinary temperatures NFPA rating (not rated) may explode on contact with 3-bromopropyne, ethylene oxide, lithium, peroxyfonnic acid, and chlorine dioxide vapor ignites on contact with boron diiodophosphide reacts violently with acetylenic compounds, metals, chlorine, chlorine dioxide, methyl azide, and nitromethane incompatible with acetylene, ammonia, chlorine dioxide, azides, calcium, sodium carbide, lithium, rubidium, and copper heating to decomposition emits toxic fumes of Hg use water spray, fog, or foam for firefighting purposes. 

Acetylene and ammonia, the gases, which are used in excess in this process, are almost completely recycled, the lithium salts are returned to the lithium metal manufacturer and there converted into the marketable lithium hydroxide. In the 1980s, the whole process was optimised to reduce the waste streams, and it was regarded as a classic example of an environment-friendly and economic production process. 

Propiolic acid is readily prepared in a one-step process using liquified acetylene, carbon dioxide and sodium, potassium or lithium metal as the starting materials [96]. Yields are substantially increased by adding a small amount of a tertiary amine such as trimethyl amine... 

Stabilized lithium acetyhde is not pyrophoric or shock-sensitive as are the transition-metal acetyhdes. Among its uses are ethynylation of halogenated hydrocarbons to give long-chain acetylenes (132) and ethynylation of ketosteroids and other ketones in the pharmaceutical field to yield the respective ethynyl alcohols (133) (see Acetylene-derived chemicals). 

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