Hydrochloric Acid → Bumetanide Impurity 118

Participants

Reaction Conditions

Reaction Steps

124 g (0.9 mol) of potassium carbonate are dissolved in 800 ml of water. To this solution, there are added portionwise 1.6 mols of p-cresol and subsequently 112 g (0.4 mol) of 2-chloro-3-nitro-5-carboxy-benzenesulphonamide and the solution is heated to 85° C. The whole is stirred for 16 hours at this temperature, cooled to 25°-30° C and acidified with concentrated hydrochloric acid to pH 1. The oil which thereupon separates is isolated from the aqueous phase and subjected to steam distillation. Alternatively, it is also possible to adjust a pH-value of 8-9, to extract the excess phenol with ethyl acetate and then to acidify the aqueous phase. After having separated in this manner the excess p-cresol, the product crystallises upon cooling. By recrystallisation from acetone/H2O, the 3-nitro-4-(4'-methylphenoxy)-5-sulphamoylbenzoic acid melting at 236° C is obtained.

Provenance & Evidence