Acetic Acid → 5-Hydroxy-12H-benzo[a]phenothiazine-7,7-dioxide

Participants

Reaction Steps

To a suspension of 5-acetoxy-12H-benzo[a]phenothiazine-7,7-dioxide (6.6 g) in methanol (200 ml) there was added 2N aqueous sodium hydroxide solution (132 ml) and the mixture was stirred in the absence of air at room temperature for 7 minutes; at that point an amber solution had resulted. There was rapidly added 10% aqueous acetic acid solution (200 ml) causing precipitation of the title compound which was collected by filtration (5.68 g). A sample (500 mg) was crystallized from THF affording purified product (250 mg), m.p. 334° C. (dec).

Provenance & Evidence