Ammonia → Saccharin

Participants

Reaction Steps

In the third step the reaction of ammonia is reacted with the reaction product produced in the second step. It is possible to react the components by injecting ammonia into the reaction mixture after the second step. Thus, it is preferable to react ammonia and the second step product by mixing an aqueous solution of ammonia with the reaction mixture after the second step. The amount of ammonia employed is preferably in a range of 3.5 - 4.5 mole per mole of the o-sulfobenzoic acid (I) or the alkali metal salt or alkaline earth metal salt thereof. Preferably, a 4 - 28 % of an aqueous solution of ammonia is used. The reaction temperature is usually in the range of 5° - 35° C, and if desired, the reaction is conducted while cooled. After the reaction with ammonia, the ammonium salt of 1.2-benzoisothiazole-3-on-1.1-dioxide (III) is obtained. The desired compound, i.e. 1.2-benzoisothiazole-3-on-1.1-dioxide (III) can be separated by precipitation by treating the solution with a mineral acid such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid or the like. In accordance with the process of the invention, the desired 1.2-benzoisothiazole-3-on-1.1-dioxide compound (III) having high purity can be easily produced in substantial industrial efficiency in yields greater than 80 % based on the o-sulfobenzoic acid.

Provenance & Evidence