Twenty grams of acetamide (0.34 mole) is dissolved in
54 g. of bromine (0.34 mole) contained in a
500-ml. Erlenmeyer flask, and the solution is cooled to 0–5° in an
ice bath. An ice-cold aqueous
50% potassium hydroxide solution is added in small portions with swirling and cooling until the color becomes a light yellow. Approximately 33–34 ml. of the caustic solution is required. The nearly solid reaction mixture is allowed to stand at 0–5° for 2–3 hours.
The mixture is treated with 40 g. of salt and
200 ml. of chloroform and warmed on the
steam bath with vigorous swirling. After 2–3 minutes the clear red
chloroform layer is decanted from the semisolid lower layer, and the extraction is repeated twice more with
200- and 100-ml. portions of chloroform respectively (Note
1). The combined extracts are dried over
sodium sulfate, the solution is filtered by gravity through a fluted filter into a
2-l. Erlenmeyer flask, and
500 ml. of hexane is added with swirling. White needles of
N-bromoacetamide begin to form at once (Note
2). After chilling for 1–2 hours, the crystals are collected with suction, washed with
hexane, and air-dried. The yield is
19–24 g. (
41–51%), m.p.
102–105° (Note
3), purity 98–100% (Note
4) and (Note
5).