A solution of 60.5 g. (0.5 mole) of dimethylaniline and 80 g. (1.05 moles) of ammonium thiocyanate in 250 cc. of glacial acetic acid, contained in a 1-l. beaker, is cooled to 10–20° in a bath of ice and water. The solution is stirred mechanically while a solution of 80 g. (25.7 cc., 0.5 mole) of bromine in 100 cc. of glacial acetic acid is added dropwise, over a period of twenty to thirty minutes, and the temperature is kept below 20° (Note 1) and (Note 2). After all the bromine has been added the reaction mixture is removed from the cooling bath and, after standing at room temperature for ten minutes, is poured into 5–6 l. of water. Most of the p-thiocyanodimethylaniline separates as a pale yellow solid (Note 3), which is collected on a suction filter and washed with water. After drying in air it weighs 50–55 g. and melts at 71–73°. An additional 10–15 g. of less pure product is obtained by making the filtrate alkaline to litmus; this requires about 1250 cc. of 20 per cent sodium hydroxide. The two fractions are combined, dissolved in about 1.2 l. of boiling ligroin (b.p. 90–100°), and filtered rapidly through a large fluted filter in a heated funnel. The product separates from the filtrate in the form of long yellow needles, and crystallization is completed by thorough chilling. The melting point of the purified product is 73–74°, and the total yield is 56–60 g. (63–67 per cent of the theoretical amount) (Note 4).