In a 500-mL, three-necked flask, equipped with a thermometer, stirrer, and a reflux condenser with drying tube, are placed 12.6 g (0.1 mol) of 1-octyn-3-ol, 154 mL of dioxane, 7.24 g (0.0504 mol) of cuprous bromide, 7.4 g of paraformaldehyde, and 18.54 g (0.183 mol) of diisopropylamine (Note 1). The resulting mixture is gently refluxed and stirred for 2 hr and then cooled to room temperature and filtered through a Celite plug. The dark-brown filtrate is concentrated under vacuum (Rotavapor) to a gummy residue and then diluted with 50 mL of water followed by 100 mL of ether and acidified with 6 N hydrochloric acid to pH 2. The ether–water layers are decanted from any residue, the ether layer is separated, and the aqueous solution is extracted with ether (5 × 50 mL). The ether extracts are combined and washed with small portions of water until pH 6.5 is reached. The organic layer is then washed with saturated sodium chloride solution and dried over anhydrous MgSO₄. After removal of ether by distillation through a 20-cm Vigreux column (water aspirator vacuum) while heating on a water bath, ≤40°C, the residual liquid is fractionated under reduced pressure through a 10-cm Vigreux column. The main fraction is collected at 41–42.5°C(0.15 mm) to give 8.65 g of pure allene (Note 2), with additional fractions of a less pure material.