United States Patent (19) 11 Patent Number: 4,626,325 Trummlitz Et Al
United States Patent (19) 11 Patent Number: 4,626,325 Trummlitz et al. (45) Date of Patent: Dec. 2, 1986 54 PROCESS FOR THE PREPARATION OF (56) References Cited 4-HYDROXY-1,2-BENZISOTHIAZOL U.S. PATENT DOCUMENTS 3(2H)-ONE-1,1-DIOXIDE 4,057,555 11/1977 Kolke et al. ........................ 548/210 75 Inventors: Gunter Trummlitz, Warthausen; 4,140,697 2/1979 Batcho et al. ....................... 426/548 Wolfgang Eberlein, Biberach; 4,404,230 9/1983 Trummlitz et al. ................. 426/548 Wolfhard Engel, Biberach; Gerhard Primary Examiner-Arthur P. Demers Mihm, Biberach, all of Fed. Rep. of Attorney, Agent, or Firm-David E. Frankhouser; Alan Germany R. Stempel 73) Assignee: Karl Thomae GmbH, Biberach an der 57 ABSTRACT Riss, Fed. Rep. of Germany The specification describes a process for preparing 4 hydroxy-1,2-benzisothiazol-3(2H)-one-1,1-dioxide, a 21 Appl. No.: 841,392 sweetener, from 1,2-benzisothiazol-3(2H)-one-1,1-diox ide by anodic oxidation in the presence of trifluoroace (22 Filed: Mar. 19, 1986 tic acid or trifluoromethanesulfonic acid and, option 30 Foreign Application Priority Data ally, in the presence of salts which increase the conduc tivity. The oxidation is effected in an anhydrous me Mar. 19, 1985 DE Fed. Rep. of Germany ....... 35098.19 dium and the 4-trifluoroacetoxy-1,2-benzisothiazol 51) Int. Cl." ................................................ C25C3/00 3(2H)-one-1,1-dioxide formed as an intermediate when, 52 U.S. C. .................................. 204/59 R; 426/548; for example, trifluoroacetic acid is used is decomposed 548/210; 548/211 with water to obtain the desired end product.
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