反应详情

To a solution of 4-acetamido-2-chlorotoluene (89.2 g, 0.486 mol) in glacial acetic acid (480 ml) that was stirred with an overhead mechanical stirrer and under argon was dropwise added bromine (28.5 ml) during a period of 2 h while the temperature of the reaction mixture was kept below 15° C. by using an ice-bath. Stirring was continued for a further 1.5 h after the addition of bromine, under an argon atmosphere. Then the brownish reaction mixture was poured into ice-water (1.8 lt), with the aid of water (1 lt), washed with water (6 lt), and dried in vacuo over P2O5. Purification by recrystallisation from acetonitrile afforded the desired product as a white crystals (61.5 g, 48%), mp 154-155° C.; 1H-NMR (CDCl3) 2.24, 2.32 (2×s, 6H, 2×CH3), 7.40, 7.73 (2×s, 2H, 3-H, 6-H), 7.49 (br s, 1H, CONH); MS (FAB, m/z): 262, 264, 266 [(M+H)+, 80%, 100%, 25% respectively; BrCl isotopic pattern];

1. customof 2 h
2. customwas kept below 15° C.
3. customThen the brownish reaction mixture
4. washwashed with water (6 lt)
5. dry with materialdried in vacuo over P2O5
6. customPurification
7. customby recrystallisation from acetonitrile