Preparation of dibromoacetylene
Dibromoacetylene is sensitive to air. All synthesis procedures should be performed in inert atmosphere. 26.5 g of 1,1,2-tribromoethylene and 10.5 g of 82% potassium hydroxide are placed in a separatory funnel of 1 liter capacity. The stopper of the funnel has two holes, through one of which passes a small tap-funnel and through the other a simple tap. The contents are treated in an atmosphere of nitrogen with 35-50 g alcohol (95%), cooling meanwhile in a stream of water. After 2 hours, 400-500 ml air-free water are added. At the bottom of the separatory funnel an oily layer of dibromoacetylene collects; this is run off into a flask filled with carbon dioxide and distilled in an atmosphere of carbon dioxide by heating in an oil bath to 100° to 120° C.
Dibromoacetylene is a colorless heavy liquid which boils at 76 °C. It has an unpleasant odor and it is soluble in most organic solvents.
The war gases chemistry and analysis, by M. Sartory, 51, 1939