In a
2-l. round-bottomed flask fitted with a mechanical stirrer and a reflux condenser are placed
30.0 g. (0.20 mole) of p-aminoacetanilide (Note
1) and 400 ml. of water. The mixture is heated on a
steam bath with stirring, and to the clear solution is added at once a hot solution of
45.2 g. (0.20 mole) of trithiocarbodiglycolic acid (p. 967) in 500 ml. of water. Heating and stirring are continued for 5 hours (Note
2). The steam bath is then replaced by an
ice bath, and the reaction mixture is cooled to 20–25°. The precipitate is removed by suction filtration. The solid is transferred to a
500-ml. Erlenmeyer flask containing 200 ml. of water. The mixture is heated on the steam bath to 70–75° while the lumps are crushed by a
glass rod to obtain a homogeneous mixture. The mixture is filtered with suction while hot, and the flask is cleaned by rinsing it with small amounts of hot water. The solid on the filter is sucked as dry as possible and then transferred to a
2-l. round-bottomed flask fitted with a reflux condenser.
Glacial acetic acid (1.5 l.) is added and the mixture is heated in an oil bath to vigorous reflux for 5 minutes (Note
3). A small amount of solid does not dissolve, and this is removed by filtration while hot (Note
4). The filtrate is stirred mechanically and cooled to 15–20° by an ice bath and kept at this temperature for 1 hour. The slightly yellow crystals are collected by suction filtration, washed successively with
25 ml. of glacial acetic acid,
100 ml. of ethanol, and
100 ml. of ether. The yield of air-dried material is
26–28 g. (
49–53% yield). The compound decomposes on heating above
240° (Note
5).