T-705 (Favipiravir) 5MG. T-705 (Favipiravir), CAS Number: 259793-96-9, Molecular Formula: C5H4FN3O2, Molecular Weight: 157. 1, Purity: greater than or equal to 98%, Appearance: Light yellow to yellow solid, Synonym: 6-Fluoro-3-hydroxy-2-pyrazinecarboxamide Avigan, Size: 5MG