[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.S(=O)(=O)(O)O.N(CC(O)=O)C(N)=O.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 (813 g.) in chlorobenzene (3,500 cc.) is added concentrated sulphuric acid (d = 1.83) (16 cc.), representing 0.095 mol per mol of ureidoacetic acid. The water formed in the reaction is removed by azeotropic distillation. After 45 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 (500 cc.) at 10° C. After drying, 3-(3,5-dichlorophenyl)-hydantoin (724 g.) melting at 199° C is obtained. Yield: 95.4%.
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