1, 1-dioxo-1, 2-benzisothiazole-3 (2H)-one sodium salt crystallization process

The invention belongs to the technical field of food additive crystallization. The invention discloses a novel crystallization process of 1, 1-dioxo-1, 2-benzisothiazole-3 (2H)-one sodium salt, and relates to the technical field of sodium salt crystallization. The method comprises the following steps: firstly, carrying out impurity removal and filtration by using activated carbon, adding a nucleating agent into a solution after filtration, and carrying out cooling crystallization and filtration in a stirring state to obtain 1, 1-dioxo-1, 2-benzisothiazole-3 (2H)-one sodium salt; the preparation method comprises the following steps: firstly, adding an alkali into a filtrate, removing ammonia gas in the filtrate, removing impurities by using activated carbon, filtering, then adding water, 2-methoxycarbonyl benzene sulfonamide and sodium carbonate or sodium bicarbonate into the filtered filtrate, reacting, and carrying out circular treatment on the obtained aqueous solution of 1, 1-dioxo-1, 2-benzisothiazole-3 (