Hydrochloric Acid → 5-(2-Chlorophenylsulphonyl)-6-methyl-1,3-benzodioxole-2-carboxylic acid

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Reaction Steps

23 g (77 mmol) of 4-(2-chlorophenylsulphonyl)-5-methyl-1,2-benzenediol are added to a finely particulate suspension of 50.9 g (385 mmol) of freshly calcined potassium carbonate in 180 ml of dry dimethylformamide and there is added dropwise thereto, in the course of 15 minutes, a solution of 8.50 g (39 mmol) of dibromoacetic acid in 80 ml of dimethylformamide. The mixture is then stirred for 15 hours at 80°. Subsequently, the reaction mixture is poured onto ice and adjusted to pH 1-2 with concentrated hydrochloric acid. The aqueous phase is extracted once more with ethyl acetate. The combined organic phases are washed with water and saturated sodium chloride solution, dried with sodium sulphate and concentrated by evaporation. The resulting brown oil is stirred with 150 ml of ethyl acetate at 0° until crystallisation occurs. The crude 5-(2-chlorophenylsulphonyl)-6-methyl-1,3-benzodioxole-2-carboxylic acid so obtained is recrystallised twice from acetonitrile, resulting in the form of sand-coloured crystals having a melting point of 211°-213.5°.

Provenance & Evidence