Preparation of deca-4,6,8-trien-1-yn-3-ol
A solution of lithium acetylide in 75 ml of liquid ammonia is prepared in a Dewar vessel by passing a steady stream of acetylene into a stirred solution of lithium amide (from lithium, 0.5 g) for 3 hours. 4 g of octatrienal in 50 ml of dry ether are introduced over 1 hour with gentle passage of acetylene; the acetylene stream is then replaced by nitrogen and the stirring continued for 2 hours. 5 g of ammonium chloride are added over 30 minutes and the stirring continued for a further 30 minutes. The contents of the Dewar are transferred to a beaker and the ammonia allowed to evaporate off through Cellophane. The product is isolated with ether and the extracts dried with sodium sulfate at 0° C in the presence of hydroquinone. Evaporation of the ether in nitrogen gives an 4.5 g of oil which rapidly solidifies. Crystallization from light petroleum (b.p. 40-60° C) gives 3.5 g or 72% of deca-4,6,8-trien-1-yn-3-ol as long colourless needles m.p. 73° C, which are rapidly transformed to a brown resin on being exposed to air.
Acetylenic compounds in organic synthesis, by R. R. Alexander, 197, 1955