Sodium, acetylide

A solution of mono-sodium acetylide in liquid ammonia is formed by passing excess of acetylene gas into the suspension of sodamide ... 

The reaction between sodium acetylide in liquid ammonia solution and carbonyl compounds gives a-acetylenyl carbinols (compare Section 111,148), for example ... 

Some unreaeted sodium may be left 011 the walls of the flask in this method and this may partly reduee soino produet, siieh as an alkylaeetylene, derived from the sodium acetylide. The preparation of sodamide is not attended by mueh splashing and little (if any) unreaeted sodium remains on the walls of the flask. Although more manipulation and a somewhat longer time is required for the sodamide method, the latter is generally preferred as it is more adaptable and somewhat less troublesome. 

Ccasionally the reaction mixture does not become completely black nor free from suspended solid here the acetylide is in an insoluble (or sparingly soluble) form, but it gives satisfactory results in the preparation of hex-l-yne. The saturated solution of the soluble form of mono-sodium acetylide in liquid ammonia at — 34° is about i- M. 

Epichlorohydrin (1 mol) was added dropwise over a period of 1.5 h to a solution of 2.2 mol of sodium acetylide in 1.5 1 of liquid ammonia. During, as well as for a period of 1.5 h after, the addition the temperature of the mixture was kept at about -45°C. The cooling bath was removed after this period and the mixture was agitated vigorously for another 3 h. The thermometer and vent were removed, and 75 g of powdered ammonium chloride v/ere added in 2-g portions with vigorous stirring. The atimonia was allowed to evaporate. 

Solutions of sodium acetylide (HC=CNa) may be prepared by adding sodium amide (NaNH2) to acetylene m liquid ammonia as the solvent Terminal alkynes react similarly to give species of the type RC=CNa... 

Next an alkyl halide (the alkylating agent) is added to the solution of sodium acetylide Acetylide ion acts as a nucleophile displacing halide from carbon and forming a new carbon-carbon bond Substitution occurs by an 8 2 mechanism... 

The properties of organometallic compounds are much different from those of the other classes we have studied to this point Most important many organometallic com pounds are powerful sources of nucleophilic carbon something that makes them espe cially valuable to the synthetic organic chemist For example the preparation of alkynes by the reaction of sodium acetylide with alkyl halides (Section 9 6) depends on the presence of a negatively charged nucleophilic carbon m acetylide ion... 

An excephon to this type of nomenclature is NaC CH which is normally referred to as sodium acetylide Both sodium acetyhde and ethynylsodium are acceptable lUPAC names... 

Sodium acetylide has an ionic bond between carbon and sodium... 

Sodium acetylide and acetylenic Grignard reagents react with aldehydes and ketones to give alcohols of the type... 

Sodium acetylide [1066-26-8] M 48.0, was prepd by dissolving Na (23g) in liquid NH3 (IL) and bubbling acetylene until the blue color was discharged (ca 30min) and evapd to dryness [Saunders Org Synth Coll Vol III 416 7955] and is available commercially as a suspension in xylene/light mineral oil. [See entry in Chapter 5.]... 

Sodium acetylide [1066-26-8] M 48.0. It disproportionates at ca 180° to sodium carbide. It sometimes contains diluents, e.g. xylene, butyl ether or dioxane which can be removed by filtration followed by a vacuum at 65-60°/5mm. Alternatively the acetylide is purged with HC=CH at 100-125° to remove diluent. NaC2H adsorbs 2.2x, 2.0x and 1.6x its wt of xylene, butyl ether and dioxane respectively. Powdered NaCaH is yellow or yellow-gray in colour and is relatively stable. It can be heated to ca 300° in the absence of air. Although no... 

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... 

Both sodium acetylide in xylene (Air Reduction Corporation) and lithium acetylide-ethylenediamine complex (Foote Mineral Co.) are now commercially available, and have been used successfully for the ethynylation of 17-keto steroids. 

Commercial Sodium Acetylide A suspension (30 ml) of sodium acete-lide (20% in exylene) is centrifuged and the solid brown sodium acetylide is taken up in 25 ml of dimethyl sulfoxide. To this is added a solution of 5 g of 5a-hydroxy-6j5-methylandrostane-3-17,dione 3-ethylene ketal in 85 ml of dimethyl sulfoxide. After stirring at room temperature overnight, ice is added and the solution diluted to about 250 ml. The tan precipitate is collected, washed with water and dried yield 4.8 g mp 202-204°. Crystallization from ethyl acetate gives a product of mp 204-206°. 

Serini reaction, 167 Simmons-Smith reaction, 107 Sodium acetylide, 138 Sodium bismuthate, 147, 149 Sodium bistrimethylsilylamide, 90 Sodium chloroacetylide, 68 Solvolytic cleavage of cyclic ethers, 267 3- (5 -Spiro-2, 2 -dimethyloxazolidi nyl) -cholestane, 360... 

Alkynes of the type RC=CH may be prepared by nucleophilic substitution reactions in which one of the starting materials is sodium acetylide (Na C=CH). 

---