[Cl:1][C:2]1[CH:3]=[C:4]([NH:9][C:10](=[O:16])[NH:11][CH2:12][C:13](O)=[O:14])[CH:5]=[C:6]([Cl:8])[CH:7]=1.C1(S(O)(=O)=O)C=CC=CC=1.O>ClC1C=CC=CC=1>[Cl:1][C:2]1[CH:3]=[C:4]([N:9]2[C:13](=[O:14])[CH2:12][NH:11][C:10]2=[O:16])[CH:5]=[C:6]([Cl:8])[CH:7]=1To a suspension of 3-(3,5-dichlorophenyl)-ureidoacetic acid (26.3 g.) in chlorobenzene (180 cc.) is added benzenesulphonic acid (1.2 g. representing 0.068 mol per mol of ureidoacetic acid). The water formed in the reaction is removed by azeotropic distillation. After 30 minutes' distillation, a limpid solution is obtained. After cooling to about 15° C, the precipitate formed is filtered off and washed on the filter with ethanol (25 cc.) at 10° C. After drying, 3-(3,5-dichlorophenyl)-hydantoin (22.2 g.) melting at 199° C is obtained. Yield: 90.5%.
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