[CH3:1][C:2]1[C:12]([N+:13]([O-])=O)=[CH:11][CH:10]=[C:9]2[C:3]=1[C:4](=[O:16])[NH:5][S:6]2(=[O:8])=[O:7].[H][H]>O.[Pd]>[CH3:1][C:2]1[C:12]([NH2:13])=[CH:11][CH:10]=[C:9]2[C:3]=1[C:4](=[O:16])[NH:5][S:6]2(=[O:8])=[O:7]33.6 g (0.13 mol) of 4-methyl-5-nitrosaccharin are dissolved in 1.2 l of water with warming to 45° C. and 5 g of Pd/C (10% on active carbon) are added. Hydrogen gas is then passed in with vigorous stirring (pressureless hydrogenation). 9 l of H2 are absorbed in the course of 4.5 hours. After cooling to 25° C., the catalyst is filtered off, and the filtrate is concentrated to a volume of 200 ml and then acidified to pH 1. The deposited precipitate is filtered off with suction, washed with water and dried under reduced pressure at 50° C. 23.4 g (0.11 mol=85% of theory) of a white solid of m.p.: 272°-273° C. are obtained.
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