Preparation of undeca-1,7-diyne
To a suspension of sodium amide in 150 ml of liquid ammonia prepared from 5 g of sodium, 21.2 g of octa-1:7-diyne in 25 ml of dry ether are added over 10 minutes with stirring and cooling. The reaction mixture is stirred for a further 2 hours, and 41 g of n-propyl iodide in 30 ml of ether are gradually added. Stirring is continued for another 6 hours, the temperature of the cooling bath being maintained at —40 °C. Working up in the standard manner, followed by distillation through a short Vigreux column gives unchanged 9.2 g of octadiyne and 14.4 g; 86% undeca-1,7-diyne, b.p. 97-99°/20 mm. nD=1.4576.
Raphael, R. A., Sondheimer, F., ibid. (1950) 115
Acetylenic compounds in organic synthesis, by R. R. Alexander, 196-197, 1955