Co-crystallization and polymorphic behaviour of 5-fluorouracil

Syntheses and single-crystal characterization of two co-crystalline 5-fluorouracil compounds with nontoxic co-formers of the GRAS list, succinic acid and adipic acid, are presented. Furthermore, the target-oriented synthon approach from methanol or ethanol (technical grade) to polymorphic form II, which is hitherto only accessible from dry nitromethane, is described.