Process for the preparation of crystal form 1 of n-(4-trifluoromethyl-phenyl)-5-methyl-isoxazole-4-carboxamide

摘要

Crystal modification 2 of N-(4-trifluoromethylphenyl)-5-met hylisoxazole-4-carboxamide (I) (leflunomid; HWA 486) is new. - New crystal modification 2 of N-(4-trifluoromethylphenyl)-5-methylisoxazole-4-carboxamide (I) has lines (diffraction angles 2theta ([deg])) of strong intensity at 10.65, 14.20, 14.80, 16.10, 21.70, 23.15, 24.40, 24.85, 25.50, 25.85, 26.90 and 29.85 and of medium intensity at 7.40, 9.80, 13.10, 15.45, 16.80, 20.70, 21.45, 22.80, 23.85, 27.25 and 28.95 in the X-ray diffraction graph using Cu-Kalpha 1 radiation in the focusing Deybe-Scherrer procedure and transmission. Compound (I) is known from US 4284786. Independent claims are included for: (A) the preparation of crystal modification 2; and (B) the preparation of crystal modification 1 of compound (I) having lines of strong intensity at 16.70, 18.90, 23.00, 23.65 and 2.05 and lines of medium intensity at 8.35, 12.65, 15.00, 15.30, 18.35, 21.55, 24.10, 24.65, 25.45, 26.65, 27.40, 28.00 and 28.30 in the X-ray diffraction graph measured and defined in the same manner as for crystal modification 2. -