Bromine → 2-(Methylamino)-1,3-benzothiazole-7-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

A solution of 163 g of bromine and 50 g of 100% acetic acid is added dropwise to a suspension of 212 g of 3-(N′-methylthioureido)-benzoic acid and 500 g of 100% acetic acid at 45-50° C. in the course of 2 hours. The mixture is then heated to 90-100° C. in the course of 2.5 hours and is allowed to react for a further 2 hours until the release of the gas has ended. After 150 g of acetic acid have been distilled off at 80-85° C. under reduced pressure, 200 g of water are added and the mixture is brought to pH 2 by dropwise addition of 30% sodium hydroxide solution. Filtration with suction at 70-80° C. and washing with water gives 179.2 g of the title compound of melting point: >330° C. HPLC analysis shows a content of 94.6% of the title compound, in addition to 3-4% of isomeric 2-methylamino-benzothiazole-5-carboxylic acid.

Provenance & Evidence