Tetrahydrofuran is then distilled u

Tetrahydrofuran is then distilled until a maximum pot temperature of 5oc at 60 mm Hg is reached, whereupon toluene (4.5 litres) is added to the mixture. Aqueous ammonia (300 ml,25% by weight) is then added to give a final pH of 9 in the water layer, the temperature is adjusted to 45-5o℃, and the mixture is stirred for 15 minutes. The toluene layer is separated , and the aqueous layer is extracted once with toluene (600 ml). The combined toluene extracts are washed with warm (50°c) water (600 ml) and are then extracted with dilute acetic acid (2.5 litres water and 800 ml acetic acid, 80% by weight).