Pyridine → Acibenzolar Acid Impurity 21

Participants

Reaction Conditions

Reaction Steps

4.0 g (0.022 mol) of benzo-1,2,3-thiadiazol-7-ylcarboxylic acid amide are dissolved in 35 ml of tetrahydrofuran, and 3.6 ml (0.045 mol) of pyridine are added. The batch is then cooled to 3° C. and a solution of 3.9 ml (0.028 mol) of trifluoroacetic acid anhydride in 12 ml of tetrahydrofuran is added dropwise. The reaction mixture is subsequently stirred for 22 hours at room temperature and then poured onto ice/water and extracted twice with ethyl acetate. The extracts are washed with water, dried over magnesium sulfate and filtered through a layer of silica gel. Concentration by evaporation gives 3.5 g (99% of the theoretical yield) of crystalline product having a melting point of 119°-122° C.

Provenance & Evidence