1. Field of the Invention:
The present invention relates to a new process for producing 1.2-benzoisothiazole-3-on-1.1-dioxide (saccharine derivatives) which is useful as a medicinal agent (sweetener for diabectics) food additives sweetener and as an intermediate for agricultural chemicals such as germicides to obtain hygienically nontoxic products. More particularly, the invention relates to a process for producing 1.2-benzoisothiazole-3-on-1.1-dioxides possesing high purity in high yield without contamination by toluenesulfonamide which may be hygienically toxic, by a sequence of new reaction steps from o-sulfobenzoic acid.
2. Description of the Prior Art:
It is known that 1.2-benzoisothiazole-3-on1.1-dioxides can be produced by the reactions of Reaction scheme (1) in which the first steps in the chlorosulfonation of toluene; the second step is the separation and purification of o-toluenesulfochloride and p-toluenesulfochloride which are produced in the first step the; third is the reaction of the o-toluenesulfochloride separated and purified in the second step with ammonia; and fourth step is the oxidation of o-toluenesulfonamide produced in the third step with a solution of bichromate in concentrated sulfuric acid J. Am. Chem. Soc. Vol. 1. page 426, 1879; BP 174, 913 and BP 682.800).