In a loosely stoppered 1-l. round-bottomed flask are placed 37.5 g. (48 ml.) of t-butyl alcohol, 150 ml. of dimethyl sulfoxide (Note 1), and a Teflon^®-coated magnetic stirring bar. The solution is heated in an oil bath which is placed on a combination magnetic stirrer-hotplate. When the temperature of the mixture reaches 125–130°, 75 g. (0.67 mole) of alcohol-free potassium t-butoxide (Note 2) and (Note 3) is added, the stopper is replaced loosely, and the mixture is stirred. When all the potassium t-butoxide is in solution, the stopper is removed, 25 g. (0.159 mole, 17 ml.) of bromobenzene is added in one portion to the hot solution, and an air condenser fitted with a drying tube is rapidly placed on the flask. The solution immediately turns dark brown, and an extremely vigorous, exothermic reaction occurs. After 1 minute the reaction mixture is poured into 500 ml. of water. The aqueous solution is saturated with sodium chloride and extracted with four 200-ml. portions of ether (Note 4). The ether extract is washed with three 100-ml. portions of water and dried over anhydrous potassium carbonate. The ether is distilled at atmospheric pressure on a steam bath to leave 17–18 g. of crude phenyl t-butyl ether (Note 5). The brown oil is distilled to yield 10–11 g. (42–46%) of pure phenyl t-butyl ether, b.p. 45–46° (2 mm.), m.p. −17 to −16°, n²⁵D 1.4860–1.4890 (Note 6). The ether may be hydrolyzed readily to phenol (Note 7).