Sodium acetylide, solution in liquid

Sodium Pbenylethynetellurolate5 An apparatus suitable for work with liquid ammonia under a nitrogen atmosphere is set up. A 500-m/flask is charged with 250 ml of liquid ammonia freshly distilled from sodium. In the liquid ammonia are dissolved 1.15 g (0.05 mol) of sodium, a catalytic amount of iron(III) nitrate is added, and 5.1 g (0,05 mol) of phenylacetylenc are added dropwise over 0.5 h to the sodium amide solution. The mixture is allowed to stand for 40 min and then 6.4 g (0.05 mol) of finely powdered tellurium arc added to the sodium acetylide solution. The ammonia is evaporated and the residue of sodium phenylethyne-tellurolate can be dissolved in an appropriate solvent for further reactions. 

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 ... 

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. 

Acetylene and Potassium in Liquid Ammonia Potassium (40 g) is dissolved in 1 liter of dry liquid ammonia. Dry acetylene is then bubbled into the solution until the blue color is discharged. A solution of 15 g of estrone in 300 ml of dioxane is prepared and diluted with 300 ml of ether, cooled, and added to the potassium acetylide solution over a period of 10 min. The liquid ammonia is allowed to evaporate, an additional 500 ml of ether is added, and the mixture is allowed to stand overnight. About 3 liters of 5 % sulfuric acid is added and the organic layer separated. The water layer is re-extracted with fresh ether, and the combined ether extracts are washed twice with 5 % sodium carbonate solution, th6n several times with water, and finally evaporated under reduced pressure. The residue is dissolved in 150 ml of methanol, then an equal quantity of hot water is added and the mixture cooled. The precipitated solid is collected, washed with cold 60 % methanol and crystallized once from methanol-water to give 14.8 g (85%) of 17a-ethynylestradiol mp 143-144°. 

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

Reactions in liquid ammonia (cf. Chapter 3, Section III) require a certain amount of care, since the solvent is low boiling (—33 ) and its fumes are noxious. Nevertheless, with reasonable caution, the preparation of an ammonia solution of sodium acetylide can be carried out as described. The reagent so prepared can then be directly used for displacements on alkyl halides or for additions to suitable carbonyl compounds. Examples of both reactions are given. 

Triphenylmethyl sodium and triphenylmethyl potassium conduct in liquid ammonia although they slowly react with that solvent.887 888 When the liquid ammonia is allowed to evaporate from a solution of triphenylmethyl sodium in ammonia, the residue is a colorless mixture of sodamide and triphenylmethane. The sodium-tin and sodium-germanium compounds analogous to sodium triphenylmethide are also strong electrolytes in liquid ammonia. Sodium acetylide in liquid ammonia is dissociated to about the same extent as sodium acetate in water.889... 

A solution of 2.5 mol of sodium acetylide in liquid NH3 (p. 17-19) is cooled to —40 C and a vigorous stream of acetylene is introduced for 2 min (3 1/min). The alkyl bromide (2.0 mol) is then added dropwise over 1 h while maintaining the temperature as close as possible to -38"C. Stirring at this temperature is continued for another 1.5 h (for the type of stirrer see fig 3), then 300 ml of high-boiling petroleum ether (b.p. >170 C) is added. The mixture is cautiously poured onto 2 kg of finely crushed ice in a 5-1 wide-necked round-bottomed (fig. 13) or conical flask. The reaction flask is rinsed with a small amount of ice water which is added to the bulk. After separation of the layers, three extractions with small amounts of petroleum ether are carried out The extracts are washed with dilute hydrochloric acid and subsequently dried over MgSO. Isolation is carried out as described in exps. 1 and 3, and in Chap. 1-2.6. The product is carefully redistilled through a 40-cm Widmer column. 1-Pentyne, b.p. 

---