Acetic Anhydride → 6-Chloro-2-methyl-4H-3,1-benzoxazin-4-one

Participants

Reaction Steps

A mixture of 2-Amino-5-chlorobenzoic acid (90 g, 524 mmole) and acetic anhydride (160 ml) was heated to reflux under nitrogen for 3 hours. The reaction became a solution during heating. The reaction was cooled to room temperature. Some solid came out during this period of time. The reaction mixture was slurried with 1 L IPA and filtered. The solid was washed with more IPA (50 ml) and dried under vacuum at room temperature for 18 hours. Product was collected as solid (91 g, yield: 89%). 1H NMR (CDCl3): 8.14 (d, J=6 Hz, 1H), 7.73 (dd, J=21 Hz, 6 Hz, 1H), 7.50 (d, J=21 Hz, 1H), 2.47 (s, 3H).

Provenance & Evidence